Edited by Jon T. LindstromEdited by Jon T. LindstromEdited by Jon T. LindstromEdited by Jon T. LindstromEdited by Jon T. Lindstrom

and John R. Clarkand John R. Clarkand John R. Clarkand John R. Clarkand John R. Clark

HORTICULTURALSTUDIES

2000

A R K A N S A S A G R I C U L T U R A L E X P E R I M E N T S T A T I O N

Division of Agriculture University of Arkansas

July 2001 Research Series 483

Technical editing and cover design by Cam Romund

Arkansas Agricultural Experiment Station, University of Arkansas Division of Agriculture, Fayetteville. Milo J. Shult, Vice

President for Agriculture and Director; Gregory J. Weidemann, interim dean, Dale Bumpers College of Agricultural, Food and

Life Sciences and associate director, Arkansas Agricultural Experiment Station, Fayetteville. CES1.10PM65. The Arkansas

Agricultural Experiment Station follows a nondiscriminatory policy in programs and employment.

ISSN:0099-5010 CODEN:AKAMA6

HORTICULTURAL

STUDIES2000

Jon T. Lindstrom, editor

Assistant Professor

Department of Horticulture

University of Arkansas

John R. Clark, editor

Professor

Department of Horticulture

University of Arkansas

Arkansas Agricultural Experiment Station

Fayetteville, Arkansas 72701

PREFACE

Horticultural Studies 2000 is the third edition of a Research Series dedicated to the horticultural programs in the University of

Arkansas Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Sciences. In this publication are

summaries of the research, extension and teaching activities that serve the horticultural industries and interest groups in Arkansas.

We hope that this Research Series will continue to be of value to persons with an interest in Arkansas horticulture. We

welcome feedback on the information contained in this edition. Additional information on the programs offered in Horticulture at

the University of Arkansas can be found on the Internet at this address: www.uark.edu/ArkHort/.

This publication is also available on the Internet at the following address:

www.uark.edu/depts/agripub/publications/researchseries/

Jon T. Lindstrom (tranell@uark.edu)

and John R. Clark (jrclark@uark.edu)

Editors

4-H Adult Leaders AssociationAlf Christianson Seed Co.Allen Canning Co.Ampac Seed Co.American Composting, Inc.American Ornamental PerennialsArkansas Electric CooperativesArkansas Farm Bureau FederationArkansas Nurserymen’s AssociationArkansas State Horticultural SocietyArkansas Golf Course Superintendents AssociationArkansas Turfgrass AssociationAsgrow Seed Co.Back to Earth ResourcesBank of FayettevilleBarbara’s GardensBASFBayer Corp.Bella Vista VillageBioWorks, Inc.Bogle Garden CityCalifornia Spinach Mildew CommitteeCalifornia Spinach CommitteeCapital Turf, Inc.Cascade International Seed Co.Chenal Country ClubClanton FarmsCleary Chemical Co.Consumer Testing LaboratoriesCricket Hill FarmsDeVaroomen Holland Bulb CompanyDouble A VineyardsDouble Springs Grass FarmDow AgriSciencesDrake FarmsDupont Agricultural ProEarth Care Technologies, Inc.Emerald Isle, Ltd.Ernst & YoungFall Creek Farm & Nursery, Inc.Farm Credit Services of Central ArkansasFianna Hills Country ClubFlowerwood NurseryGalbraith Greenhouse and NurseryGerber Products Co.Golf Cars of ArkansasGolf Course Superintendents Association of AmericaGowan Co.Greenleaf Nursery Co.Griffin Chemical L.L.C.Griffin Corp.Hall, Estill, Hardwick, Gable, Golden & Nelson, PCHines NurseriesHumalfa, Inc.International Sulfur Inc.International Seed Co.ISK Biotech Corp.J. Frank Schmidt & SonsJacklin Seed Co.Jim’s Supply Company, Inc.Johnson Seed Co.Johnny’s SeedsKalo Inc.

Keeling Irrigation Co.Little, ChrisLove Box Co.McClinton Anchor Inc.Milliken Chemical Co.Mitchener, JanetMoltan, Inc.Morningside NurseryNational Science FoundationNational Turfgrass Evaluation ProgramNelms Lincoln MercuryNetafim IrrigationNorth Creek NurseriesNovartis Crop Protection Inc.Novartis Seed Co.Ocean Organics Inc.Oldridge VineyardsOzarks Co-op WarehouseOzarks ElectricPace, RogerPinnacle Country ClubPittman NurseryPost Family Winery and VineyardPremium BrandsQuail Valley Farm, Inc.Razorback Foundation, Inc.Revelle IrrigationRiverbend NurseryRohm & Haas Co.Safe Harvest Corp.Seeds WestSmith, JeffSoil Testing and Research BoardSonoma Grapevines, Inc.Springdale Country ClubSPSS ScienceSquare Shooter Inc.Stark Brothers Wholesale Co.Stephens, Inc.Steve’s Sod StoreStine Microbial ProductsStonebridge Meadows Golf ClubSunGro, Inc.SyngentaTerra IndustriesTexel ProductsThermo Trilogy Corp.Toyota FoundationTreessentials CompanyUA Division of AgricultureUniroyal Chemical Co.United States Golf AssociationUniversity of Arkansas Teaching and Learning Support CenterVan Bloem GardensVan Hoorn NurseryVineyard Industry Products Co.Warren Tomato MarketWater-Rings Inc.Western Seed Inc.Westwood GardensWilliams Lawn Seed Co.Winrock Grass FarmWinter Garden Spinach Producers

SPECIAL THANKS

Thanks are expressed to the donors listed below who contributed to horticulture programs in 2000. External support of all

programs is critical to the continuing enhancement of horticulture industries in Arkansas.

2000 Highlights

The Department of Horticulture continued to grow and

evolve during 2000.

Dr. John R. Clark served as interim department head from

September 1999 until July 2000. John did an outstanding job

taking care of the daily business of moving the department for-

ward. His leadership united the department and coalesced and

focused the efforts of the department. John was instrumental in

developing a young faculty mentoring program that serves as

the model for the college. He also maintained his outstanding

breeding and research programs. The department and I thank

him for all of his hard work and lost sleep.

I joined the department as the new head in July 2000 and I

am very glad to be here. Much of my time since arriving has

been spent learning about Arkansas horticulture. I have been

very pleased and impressed with what I have learned thus far.

PEOPLE

Dr. James Cole began his duties in landscape horticulture

in February 2000. He taught an introductory class in landscape

design and developed several research projects in landscape

establishment and management. Dr. Douglas Karcher, research

and teaching in turfgrass science, started in May 2000. Doug

has developed an active and successful research program in golf

course and turfgrass management. Both of these new faculty

members contributed research reports to this publication and I

am sure we will see great things from these gentlemen in the

future.

During the year we interviewed several excellent candi-

dates for the new floriculture position. Dr. Mike Evans, Depart-

ment of Horticulture at Iowa State University, joined our

department in April 2001 in this capacity.

Sadly, Ray (Andy) Allen, research specialist in fruit crops,

left the UA for an extension-research position in North Caro-

lina. His good work is missed. Ms. Janet Funk, our accounting

technician, left Horticulture for a position with Entomology

and Ms. Zandra Hood came on board as the accountant for

Horticulture and Entomology. Ms. Ani Pecoraro also joined

the department as an accounting technician. She, like Zandra,

will work for both Horticulture and Entomology.

Several graduate students joined the department in 2000.

They include: Ms. Tina Buxton (advisor Dr. Cole); Ms. Chrislyn

Drake (advisor Dr. Clark); Ms. Beckie Gard (advisor Dr. Teddy

Morelock); Mr. Yoshiaki Ikemura (advisor Dr. Karcher); Mr.

Chris Lake (advisor Dr. Keith Striegler); Mr. Scott Maxwell

(advisor Dr. Curt Rom); Mr. John McCalla (advisor Dr.

Richardson); and Mr. Lee Ramthun (advisor Dr. Cole). Gradu-

ate students finishing their course of study during 2000 include:

Ms. Jennifer Kirkpatrick (advisor Dr. Morelock), and Ms. Kerry

Roberto (advisor Dr. Gerald Klingaman).

Any department is only as good as the creative, hard-

working people who develop and implement its programs. Our

folks are among the best and their skills and contributions are

appreciated.

PROGRAMS - TEACHING

Undergraduate education in horticulture continues to be one

of the brightest areas for the department and the Bumpers Col-

lege. The new curricula developed in 1999 were fully initiated

and they required only some minor refinements during the year

2000. The increase in enrollment during 1999 was sustained in

2000; we now have approximately 100 undergraduates in the

department. The number of Turf and Landscape Horticulture

majors continues to grow and now represents half of our under-

graduate students. Scholarships for horticulture students topped

$83,000.00 for 38 students in 2000.

We are planning to increase the presence of the department

in Arkansas and surrounding states in the future to promote the

undergraduate and graduate programs.

A non-thesis Master’s Degree in Horticulture was initiated

in 2000 and should be fully functional by fall 2001. This degree

is aimed at folks who desire greater technical training in horticul-

ture but are not interested in pursuing a research-related degree.

The Horticulture Display Gardens adjacent to Plant Sci-

ences continue to develop and will eventually fill the entire court-

yard. The gardens have become places for people to gather and

for outdoor events. Additionally, the gardens provide many new

materials for teaching.

PROGRAMS - EXTENSION

Extension had a very busy year. The Master Gardener pro-

gram continues to expand with 450 new Master Gardeners

graduating from the program in 2000, making a total of 1,806

active Master Gardeners in the state. The program has expanded

to 46 counties.

Mass media continues to be a strong part of the horticul-

ture extension program. Besides weekly newspaper columns

by Ms. Janet Carson and Dr. Klingaman, Horticulture exten-

sion specialists participated in weekly radio shows and furnished

numerous news stories through interviews. “Today’s Garden,”

a 30-minute television show, continues to be aired on local cable

access channels statewide and two to three times a month on

AETN—the state educational television network— dramatically

increasing the viewing audience.

The 2000 Arkansas Flower & Garden Show in Little Rock

attracted more than 10,000 participants to view gardens, hear

seminars and gather new information. Similarly, the Arkansas

River Valley Lawn & Garden Show in Fort Smith continued to

grow in 2000. Pine Bluff, Mountain Home, Mountain View,

Smackover, and Camden began similar gardening shows or

seminars last year.

Dr. Jim Robbins’ program continues to build on the strong

foundation laid during his second year, with the overall goal to

improve and increase Arkansas’ commercial ornamental horti-

cultural business. Dr. Robbins’ extension program continues to

draw solid research support. In 2000, Dr. Robbins initiated a

quarterly ornamentals newsletter, conducted certification train-

ing for the Arkansas Nursery Association, and, with Ms. Carson,

continued developing horticultural demonstration/training out-

reach in central Arkansas. Dr. Klingaman continues working

with the commercial greenhouse industry and ornamental trade

associations.

Dr. Craig Andersen, Extension Vegetable Specialist, assisted

in developing one new farmers’ market, worked to enhance five

existing markets, and assisted the planning of several more

markets across Arkansas. Dr. Paul Cooper, Monticello, contin-

ued with tomato cultivar evaluations in an expanded effort to

find genetic resistance or tolerance to tomato spotted-wilt vi-

rus, which is devastating Arkansas tomato production. Dr.

Striegler continued developing trials and research on grapes,

strawberries, and other commercial fruit crops across Arkansas.

PROGRAMS - RESEARCH

Research programs grew in several areas during 2000. Many

of the accomplishments by faculty and students in Horticulture

and other departments are discussed in the following research

reports.

Plant evaluations by Drs. Jon Lindstrom, Robbins, and

Klingaman continued at three Arkansas research sites. Hot

weather and drought during summer 2000 and prolonged cold

during the winter of 2000 will surely provide a rigorous test for

some selections.

Drs. Richardson and John Boyd (UA Extension) continue

to expand turfgrass research and Dr. Karcher implemented new

studies in turfgrass and golf course management. Several grants

were obtained benefiting the Arkansas green industry.

Drs. Clark, Morelock, and Brad Murphy cooperated with

Dr. Luke Howard (Food Science) and a consortium of other

scientists to acquire a $2.5 million USDA grant for functional

foods research.

Dr. Cole established studies evaluating compost in trans-

planting ornamentals at three Arkansas sites and is working in

cooperation with Oklahoma State University to solve nursery

production problems with ornamentals.

Drs. Rom, Striegler, and Clark are expanding fruit man-

agement research, cultivar evaluation, and fruit breeding. Dr.

Clark introduced several cultivars of peaches (‘Goldnine’,

‘GoldJim’, and ‘Roygold’) and nectarines (‘Arrington’, ‘Brad-

ley’, and ‘Westbrook’).

Dr. Morelock expanded the selections in his program de-

veloping southern peas and spinach for the regional vegetable

industry.

David Hensley, Professor and Head

Department of Horticulture

Computer Programs Integrated into a Home Landscaping Course .............................................................................. 14

FRUITS

Light Relations and Yield of Apple Tree Canopies as Affected by Tree Training System ........................................... 17

Evaluation of Southern Highbush Blueberry Cultivars for Production in Southwest Arkansas .................................. 21

‘Goldnine’, ‘GoldJim’, and ‘RoyGold’ Cling Peaches ................................................................................................. 24

Antioxidant Content of Fruit Cultivars ......................................................................................................................... 26

‘Westbrook’, ‘Arrington’, and ‘Bradley’ Nectarines .................................................................................................... 28

Determination of Chilling Requirement of Arkansas Thornless Blackberry Cultivars ................................................ 30

The Effects of Transitioning a Mature High-Density Orchard From Standard Herbicide Ground-Cover

Management System to an Organic Ground-Cover System .................................................................................... 33

Size Control of Peach Trees Using Copper-Impregnated Polypropylene Fiber Growbags: A Greenhouse Study ...... 37

Early Performance of Peach Rootstocks forArkansas .................................................................................................. 40

Red Raspberry Primocane Growth and Development in Two High-Temperature Environments in Arkansas ............ 44

VEGETABLES

Tomato Cultivar Trial Results, 2000............................................................................................................................. 48

TURFGRASSES AND ORNAMENTALS

Evaluation of Fungicides for Control of Brown Patch in Tall Fescue Lawns .............................................................. 52

Fungicide Effectiveness in Controlling Foliar Diseases of Three Euonymus fortunei Cultivars ................................. 54

Plant Growth Regulator Effects on In Vitro Propagation of Itea virginica ‘Henry’s Garnet’ ...................................... 56

Herbicide Evaluations for Establishment of Newly-Seeded Bermudagrass ................................................................ 58

Evaluation of 10 Slow-Release Fertilizers on the Growth of Three Woody Plants at a

Commercial Container Nursery .............................................................................................................................. 61

Impact of Organic Amendments and Fertilization Strategies on Establishment of Zoysiagrass Turf from Sprigs ...... 64

Performance of Creeping Bentgrass Cultivars in Arkansas: 1999-2000 Report .......................................................... 68

University of Arkansas Plant Evaluation Program: 1999 Plants/2000 Report ............................................................. 72

Effect of Liner Age on Subsequent Growth in Container Production .......................................................................... 75

Incidence and Control of Localized Dry Spot on Arkansas Putting Greens ................................................................ 77

Conversion Table .......................................................................................................................................................... 80

HORTICULTURAL STUDIES 2000

TABLE OF CONTENTS

14

AAES Research Series 483

COMPUTER PROGRAMS INTEGRATED INTO A

HOME LANDSCAPING COURSE

James T. Cole1

IMPACT STATEMENT

Basic Home Landscaping is a required course for students

in the Landscape Horticulture concentration of the Turf andLandscape Horticulture major at the University of Arkansas.Home landscaping courses have traditionally relied on hand-drawn graphics. The teaching of techniques of drawing land-scape graphics is a full-semester course in most landscape ar-chitecture programs. The time required to teach landscape graph-ics in an all-encompassing landscape design class can take awayfrom time needed for teaching landscaping principles and tech-niques. Also, many nurseries and landscape designers now usecomputer software packages to produce complete, professionaldrawings in a fraction of the time required for hand-drawn plans.Computer-assisted design in the Basic Home Landscapingcourse was evaluated and incorporated successfully.

The Department of Horticulture at the University of Ar-kansas has offered two courses in landscape design for manyyears. These classes were traditional design classes in that thestudents were taught how to produce hand-drawn landscape de-signs. The Undergraduate Program Committee reduced thecurriculum in the Landscape Horticulture concentration to onelandscape design class and incorporated computer software pro-grams into the class. Landscape designers and nurseries are nowusing computer programs to increase their productivity. Stu-dents with experience using computer programs to design land-scapes will have an advantage in the job market.

Numerous landscape-design software packages were in-vestigated and recommendations of several practicing landscapedesigners were solicited before a collection of software pro-grams was chosen. Many of the software manufacturers hadfree trial versions available. The trial versions were tested forease of use and ability to create professional, quality designs. Acollection of software was chosen to include a two-dimensionaloverhead site-design program. These particular programs en-able the designer to create a perspective view of the landscapeusing digital images of landscape plants. The program also in-cluded the ability for designers to create a bid sheet for all ofthe materials and labor required to install the landscape. Studentsused the collection of software programs to create landscape plansas part of Basic Home Landscaping in the Fall 2000 semester.

The Fall 2000 Basic Home Landscaping class had 16 stu-dents enrolled, which is large for a class of this type. The courseobjective was to equip students with the skills necessary to cre-ate aesthetically pleasing and functional landscape designs forresidential and small commercial properties utilizing the land-scape-design software package. Initial enthusiasm for the classand the software was very high. Some students had been ex-posed to computer-generated landscape designs at retail nurser-ies where they have been employed.

Computer skills varied dramatically from student to stu-dent and were not as high as anticipated. Some students requiredindividual help in learning basic computer functions such asopening files for class assignments. A few students had usedother graphics programs and had an understanding of some ba-sic commands of the software package. Early assignments in-volved the students using the software tutorials to familiarizethemselves with the program commands. Students progressedto including a landscape-materials key and a title block on all oftheir assignments. The class spent one laboratory period exam-ining landscapes in Fayetteville to expose students to proper-ties that were well landscaped and to those that were not. Thisfield trip assisted students in re-creating landscape features andprinciples seen and discussed on the trip in their computer designs.

As the semester progressed, students realized the computerprograms were capable of creating professional results, but thisdid not make the creation of the designs easy. Design assign-ments ranged from designs for newly constructed homes,through designs for homeowners to install and maintain them-selves, to designs intended to interpret a mental picture a home-owner already has for the property. Typically, students underes-timated the time required to complete design assignments.

Overall, students enjoyed creating designs on the computerand the professional appearance it gave to their assignments.Unfortunately, the class was unable to print their designs to scalein color. The computer laboratory does not currently have a plot-ter that the class could use to print their assignments. Studentswere limited to printing their assignments on 11 x 17-in. paper.This problem should be remedied by the Fall 2001 semesterwhen the laboratory will have a color, large-format printer in-stalled. When the class is offered again in the fall semester of2001, both hand-drawn and computer-generated designs willbe incorporated into the class. Utilizing both methods willbroaden student skills and give them a better appreciation of

the capabilities of the computer software package.

1 Department of Horticulture, Fayetteville

15

Horticultural Studies 2000

FRUITS

16

AAES Research Series 483

17

Horticultural Studies 2000

LIGHT RELATIONS AND YIELD OF APPLE

TREE CANOPIES AS AFFECTED BY TREE

TRAINING SYSTEM

Ray A. Allen and Curt R. Rom1

IMPACT STATEMENT

For an orchard to be economically sustainable, it must

maximize production volume early in the orchard life. The pri-

mary factors affecting both earliness of yields and maximum

yields are rootstock and tree training system. To evaluate these

effects, three tree-training systems—the central leader (CL), the

slender spindle (SS), and the vertical axis (VA)—were com-

pared during the period 1992-1997 (third through eighth sea-

sons) at the Arkansas Agricultural Research and Extension Cen-

ter, Fayetteville. All training systems had statistically similar

yields per tree except in 1995 and 1997. Orchard productivity

(yield per hectare) was significantly higher for the SS system in

most years until 1996, when all systems had similar yields. The

SS system had significantly higher light interception than ei-

ther the CL or VA in the earlier years of the trial and maintained

statistically similar light interception as the systems began to

reach maturity.

BACKGROUND

In Arkansas, most apple orchards are traditionally planted

to low-density systems (150-250 trees/acre), where large trees

take up to 7-10 years to reach full production. With the rising

costs of fruit production, it is imperative that orchards become

as efficient as possible. One method of improving orchard ef-

ficiency is to choose tree training systems that encourage early

and increased production. Yield has been linked to light inter-

ception by the system, with systems that intercept more light

having higher yields. Higher density orchard systems, using size

controlling rootstocks, have been shown to have higher light

interception and higher yields in the early years of the orchard

than low density systems using large trees. Previously, these

systems have never been systematically compared for produc-

tivity and adaptability in Arkansas.

RESEARCH DESCRIPTION

An apple orchard tree-training system trial was established

at the Arkansas Agricultural Research and Extension Center,

Fayetteville, in 1990 as part of a larger trial established at mul-

tiple sites within the United States by the NC-140 Pome and

Stone Rootstock Evaluation Committee. The trial consisted of

three tree-training systems with two cultivars, Empire and

Jonagold. Tree spacings in the trial were 2 m x 4.5 m for the

CL, 1.6 m x 4.0 m for the VA, and 1.25 m x 3.25 m for the SS

resulting in tree densities of 1111, 1495, and 2462 trees/ha, re-

spectively. Trees received supplemental irrigation by

microsprinklers and were provided minimal protection

against insect and disease pests.

Yield per tree was measured each year and yield per hectare

was calculated for each system by multiplying average yield

per tree by the number of trees in a hectare for that system.

Light interception (light at the ground level) by the different

orchard systems was measured at several times during the sea-

son in 1994-96 with a Ceptometer® (Decagon Instruments)

measuring photosynthetic light, 400-700 nm.

FINDINGS

Yield per tree was only minimally affected by system (Table

1). Training system had its greatest yield effect in 1997 when

the larger volume CL trees (data not presented) had significantly

higher per-tree yields than either SS or VA trees. In 1997, SS

and VA were similar, although the larger VA trees had higher

yields than the smaller SS trees. Unfortunately, the years 1994

through 1996, in which light measurements were taken, were

characterized by abnormal crops due to environmental influ-

ences (excessive heat) and disease (severe fireblight and bit-

ter-rot infections). Thus, yield was lower (Table 1) than would

be expected under normal conditions and standard management.

In those years, the greatest effect on yield was cultivar (data not

shown), reflecting the adaptability or resistance of different cul-

tivars to adverse environmental conditions and disease.

In contrast to yields per tree, productivity as yield per hect-

are was significantly affected by system. The SS had higher

yields than CL, with VA being intermediate in three of the six

cropping years, but by the time all the trees reached maturity,

differences were no longer significant.

The SS had the greatest light interception on all dates in

1994 and was significantly higher than CL on all dates after

shoot growth had begun (Table 2). The CL had the lowest light

interception on all dates except 22 Sept., when CL and VA were

the same. Central leader trees at this age were still filling their

1 Both authors are associated with the Department of Horticulture, Fayetteville.

18

AAES Research Series 483

allotted spaces. In 1995 (the sixth season), light interception

measurements were made at full bloom and every 7-10 days

from full bloom until 9 June, and then monthly until October

(Table 2). At this age differences in light interception had di-

minished. Whereas relative differences between the two sys-

tems had been around 10 to 12% of full sun in 1994, differ-

ences in 1995 remained around 5 to 8% of full sun until the end

of the season, when they reached 12% of full sun. Again, the

VA had intermediate values. In 1996, light interception was mea-

sured at various phenological stages. Unlike previous years,

system had no significant effect on light interception on any

sample date (data not shown). Light interception by the indi-

vidual systems followed the same pattern as the previous sea-

sons and the SS system typically had 6% higher light intercep-

tion than CL and VA.

Over the course of this study as the trees continued to fill

their space and maximize bearing capacity, differences in light

interception among tree-training systems diminished and be-

came non-significant by the last year of the study (1996). Even

though the differences in light interception as affected by tree

training systems decreased, the general trend in light intercep-

tion continued; more densely planted trees had higher light in-

terception. The SS system, with 2462 trees/ha, had the highest

light interception levels in all three years, and the CL system,

with only 1111 trees/ha, had the lowest light interception in all

three years. Since differences among systems decreased annu-

ally, extrapolating backwards one can assume that the differ-

ences in light interception were greater among systems in the

first years of the orchard. Tree training systems have the most

significant effect on light interception (Table 2) and productiv-

ity (Table 1) early in the life of the orchard, but as orchards

mature, the effect of tree training system decreases as long as

the orchards are well designed, well maintained and healthy.

Yields per hectare were not highly correlated with light

interception at any single measurement date (Table 3), although

a close relationship is reported in the literature. This may be

due in part to experimental variation due to crop loss from

fireblight or environmental conditions (heat breakdown) and

the small differences observed in light interception among the

three systems studied. Yield patterns followed the same trend

as light interception with regard to tree density per hectare, with

the more dense SS having higher yields than the VA, which had

higher yields than the CL (Table 1). By 1996, however, the train-

ing systems had begun to reach their mature bearing capacity

and were no longer significantly different in yield per hectare.

Light interception in any season or averaged across the three

seasons, either as estimated average daily light interception or

estimated cumulative seasonal light interception, was corre-

lated to tree density (r=0.95, 0.93, respectively). When yield

per hectare was regressed against estimated cumulative seasonal

light interception by the three systems during the period 1994-

96, yield was positively correlated to light interception (yld =

0.006125 x ( -0.693) Est. Cum. Interception, r2=0.55). This

suggests that the impact of orchard management and training

system on yield is in the early years when high tree density

results in highest light interception both early each season and

during the early years of the orchard.

Table 1. The influence of tree training system and cultivar on yield (per tree) from 1992-1997 in

the NC-140 Orchard Systems Trial at Fayetteville, Ark.

Training systemz 1992 1993 1994 1995 1996 1997 ‘92-’97 Cum.

Yield per tree (kg)

CL 3.7 ay 13.8 a 3.7 a 10.5 a 14.6 a 42.9 a 89.2 a

SS 3.8 a 14.4 a 4.2 a 6.9 b 6.1 a 26.3 b 61.8 b

VA 5.2 a 18.0 a 4.8 a 9.1 ab 13.0 a 33.3 b 84.7 a

Yield per hectare (1000 kg)

CL 3.4 b 15.3 c 3.9 a 11.9 b 16.1 a 50.5 a 89.2 a

SS 10.3 a 33.0 a 10.4 a 16.5 a 13.5 a 54.0 a 61.8 b

VA 7.7 ab 27.0 b 7.1 a 13.7 ab 19.4 a 49.76 a 84.7 a

z CL = Central Leader, SS = Slender Spindle, VA = Vertical Axisy Mean separation within main effects by LSMEANS/PDIFF (P≤0.05).

19

Horticultural Studies 2000

Tab

le 2

. L

igh

t in

terc

ep

tio

n e

xp

ressed

as a

perc

en

tag

e o

f fu

ll s

un

fo

r severa

l d

ate

s i

n 1

994,

1995,

1996

as

aff

ec

ted

by

tre

e t

rain

ing

, F

ay

ett

ev

ille

, A

rk.

Measure

ment

date

s (

days a

fter

blo

om

) -

1994

Tra

inin

g0

2 M

ay

11 M

ay

21

Ju

ne

26

Ju

ly0

1 S

ep

t.2

2 S

ep

t.0

7 O

ct.

Avg

.syste

mz

(14)

(23)

(64)

(99)

(136)

(157)

(172)

CL

41.2

ay

37.2

b48.1

b44.3

b44.1

b45.6

b42.3

b43.2

SS

47.5

a46.2

a60.4

a55.8

a54.3

a56.4

a55.4

a53.7

VA

43.7

a39.4

b54.0

ab

51.4

ab

50.6

ab

44.8

b47.8

ab

47.4

Measure

ment

date

s (

days a

fter

blo

om

) -

1995

03

10

17

23

01

08

17

24

30

09

01

21

02

Avg.

Apr.

Apr.

Apr.

Apr.

May

May

May

May

May

June

Aug.

Sept.

Oct.

10%

FB

PF

(8)

(16)

(23)

(32)

(39)

(45)

(54)

(107)

(158)

(169)

blo

om

CL

19.1

ay

27.2

a26.1

a29.2

a33.3

a32.6

a41.5

a44.1

a48.0

a50.0

a4

9.7

a4

8.8

b4

8.9

b3

6.3

SS

22.2

a29.4

a28.6

a32.2

a37.2

a38.1

a49.7

a49.5

a54.2

a57.3

a58.0

a59.5

a60.2

a39.7

VA

19.5

a28.4

a27.0

a30.1

a33.5

a33.8

a46.9

a48.1

a50.8

a53.8

a5

3.8

a5

4.1

ab

51

.5 b

40

.9

z C

L=

Centr

al Leader,

SS

=S

lender

Spin

dle

, V

A=

Vert

ical A

xis

.

y M

ean s

epara

tion w

ithin

main

effects

and d

ate

s b

y L

SM

EA

NS

/PD

IFF.

Diffe

rences a

re s

ignific

ant

at

(P≤0

.05

).

20

AAES Research Series 483

Table 3. Correlation r2 of yield per hectare with light interception on several dates in 1994, 1995, and 1996 for

two apple cultivars, Empire (EM) and Jonagold (JG). Values are r values for the correlation.

Correlation of yield to light interception at a specific date (r)

1994 1995 1996

r2 r2 r2

Sample Date Both Date Both EM Date Both JG

1 02 May 0.01 nsz 03 Apr. 0.06 ns 0.50** 30 Apr. 0.04 ns 0.32 ns

2 11 May 0.06 ns 10 Apr. -0.08 ns 0.32ns 07 June 0.13 ns 0.36 ns

3 21 June 0.19 ns 17 Apr. 0.05 ns 0.42* 30 July 0.11 ns 0.37 ns

4 26 July 0.10 ns 23 Apr. 0.08 ns 0.43* 26 Aug. 0.05 ns 0.35 ns

5 11 Aug. -0.11 ns 01 May 0.02 ns 0.47* 17 Oct. 0.01 ns 0.30 ns

6 22 Sept. -0.07 ns 08 May 0.12 ns 0.40*

7 17 May 0.17 ns 0.10ns

8 24 May 0.15 ns 0.43*

9 30 May 0.15 ns 0.32ns

10 09 June 0.17 ns 0.37*

11 01 Aug. 0.23 ns 0.36ns

12 21 Sept. 0.21 ns 0.40*

13 02 Oct. 0.20 ns 0.37ns

z Ns = not significant, * = significant at the P<0.05, ** = significant at theP<0.01.

21

Horticultural Studies 2000

EVALUATION OF SOUTHERN HIGHBUSH

BLUEBERRY CULTIVARS FOR PRODUCTION

IN SOUTHWEST ARKANSAS

P. Manjula Carter1, R. Keith Striegler2, and John R. Clark2

IMPACT STATEMENT

Blueberries have been an important crop for Arkansas since

the 1980s. Traditionally, rabbiteye (Vaccinium ashei) cultivars

dominated blueberry production in southwest Arkansas due to

their adaptation to the region. However, rabbiteyes are suscep-

tible during bloom to the late winter freezes experienced in

southwest Arkansas, and they tend to ripen later in the season

compared to highbush blueberries (V. corymbosum). The sub-

sequent need for an earlier ripening blueberry has been suc-

cessfully met by the southern highbush blueberry, a hybrid of

northern highbush (V. corymbosum) and one or more southern

Vaccinium species (most commonly V. darrowaei). These hy-

brids ripen up to a month earlier than rabbiteye blueberries. Pre-

vious research has shown that southern highbush cultivars vary

in susceptibility to frost damage, based on the chilling require-

ment of each cultivar. Cultivar testing has been necessary to

determine the cultivars of southern highbush best adapted to

southwest Arkansas. In a four-year study, several southern high-

bush cultivars were evaluated for productivity and reliability of

cropping at the Southwest Research and Extension Center at

Hope. ‘Ozarkblue’ and ‘Legacy’ showed the most promise at

this location. ‘Ozarkblue’ was developed at the University of

Arkansas and has been productive in southwest Arkansas. Its

higher chilling requirement compared to other southern high-

bush cultivars and possibly higher flower tissue hardiness has

contributed to reliable cropping.

BACKGROUND

Northern highbush blueberries were first domesticated in

New Jersey in 1910. This type of blueberry was first commer-

cially produced in northwest Arkansas in the 1970s, but it was

ill adapted to the climate of southwest Arkansas. Only south-

ern- adapted rabbiteye cultivars were found to be adapted to

this region (Moore, 1976). Recently, southern highbush blue-

berries have been developed from hybrids of northern highbush

(V. corymbosum ) and southern adapted types (V. darrowaei, V.

ashei). Breeding and testing of southern highbush cultivars at

the Arkansas Agricultural Experiment Station began in the

1980s. The percentage of V. darrowaei in the parentage of south-

ern highbush types has a strong influence on bud hardiness

(Clark et al., 1996). Those having less than 25% V. darrowaei

in their makeup tend to be more hardy. For example, Ozarkblue

with 13% V. darrowaei has demonstrated reliable fruiting in

both northwest and southwest Arkansas (Clark et al., 1996).

However, most southern highbush are more suited to traditional

rabbiteye areas and are not productive in areas of Arkansas where

northern highbush is grown. Early ripening and frost tolerance

in southern highbush provide growers with a viable option to

rabbiteye and an economic edge for fresh market sales in south-

west Arkansas.

RESEARCH DESCRIPTION

A blueberry planting was established in 1994 at the South-

west Research and Extension Center, Hope. Initially, the trial

contained the following cultivars: Bladen, Blueridge, Cape Fear,

Cooper, Georgiagem, Gulf Coast, Legacy, O’Neal, Ozarkblue,

and Summit. ‘Brightwell’ and ‘Premier’ (rabbiteyes) were in-

cluded as standards for comparison. Following two years of

data collection, the southern highbush cultivars Bladen,

Blueridge, Brightwell, Cape Fear, Cooper and Gulfcoast were

removed from the trial due to low productivity and poor vigor,

and the rabbiteye cultivar Brightwell was removed as only one

rabbiteye cultivar was needed for further comparative purposes.

The experimental design was a randomized complete block, with

two plants per plot. Only one plant from each plot was used in

data collection. The plants were grown on raised beds. The plant-

ing hole had one gallon of peat moss added at planting and plants

were mulched with pine straw to a depth of 6 in. Fertilizer was

applied annually at a rate of 120 lb N/acre and soil pH was

maintained at approximately 5.2. Data collected from 1997

through 2000 included dates of bud swell, 10% bloom and 50%

bloom, total yield per plant, and berry weight. Data were ana-

lyzed using SAS and means were separated by least significant

difference (LSD).

FINDINGS

Although the first crop was produced in 1996, severe frost

damage in this year reduced yields significantly in nearly all

1 Southwest Research and Extension Center, Hope

2 Department of Horticulture, Fayetteville

22

AAES Research Series 483

cultivars. Therefore, only data from 1997 through 2000 are pre-

sented. There was a significant interaction between year and

cultivar for bud swell, 10% and 50% bloom, indicating that

annual weather patterns greatly influenced all stages of bloom.

Due to its late blooming character, ‘Ozarkblue’ was not as sus-

ceptible to frost damage as the other cultivars (Table 1). De-

spite a 20% yield reduction in 1996 due to frost, ‘Ozarkblue’

still had the largest crop of all cultivars that year, and many

produced no crop (data not shown). ‘Georgiagem’, ‘Legacy’

and ‘O’Neal’ were similar in their bloom characteristics and

tended to bloom earlier than ‘Premier’. ‘Summit’ reached bud

swell later than all the other cultivars except ‘Ozarkblue’, but

was comparable to ‘Premier’ and ‘Georgiagem’ by 50% bloom

(Table 1).

Total plant yields were variable from year to year (Table

2). Yield data were influenced by environmental conditions

during the study, especially in 1999 and 2000. Yields for all

varieties were reduced in 1999 compared to 1998. This can be

attributed to a lack of adequate chilling due to the mild winter

in 1999, which resulted in delayed budbreak. Chilling was not

measured on site, but was below normal based on the lack of

adequate budbreak in peach cultivars with known chilling re-

quirement at the same site. The yield loss was most dramatic

for ‘Ozarkblue’, indicating that this cultivar has a higher chill-

ing requirement than the others. Yields in 2000 were also lower

than in previous years for all cultivars except ‘Premier’. De-

spite yearly fluctuations, ‘Ozarkblue’ and ‘Legacy’ had the high-

est yields overall, producing an average of 10,990 and 10,306

lbs/acre, respectively, more than double the average yield of

‘Premier’. ‘Legacy’ bloomed earlier than ‘Premier’ but appeared

to compensate for frost damage during bloom and was consis-

tently high yielding.

Berry size was similar for all cultivars except ‘Legacy’

and ‘Georgiagem’, which tended to have smaller berries (Table

3). ‘Legacy’ compensated for small berry size by producing a

large number of berries. Berry size for ‘Premier’ in 1999 was

larger than in other years, possibly due to the mild winter in

1999 and less frost damage to blooms. ‘Ozarkblue’ and ‘Sum-

mit’ had the most consistent berry weight across years, both

averaging 1.4 g compared to 1.3 g for ‘Premier’.

LITERATURE CITED

Clark, J.R., R. Bourne, and E. Gbur. 1996. Flower bud hardi-

ness and shoot hardiness of southern highbush blueberry

cultivars. Fruit Var. J. 50:98-104.

Moore, J.N. 1976. Adaptation and production of blueberries in

Arkansas. Ark. Agric. Exp. Sta. Bulletin 804, 30 pp.

ACKNOWLEDGMENTS

The authors thank Jack F. Young for data collection during

the first three years of the trial and Michael J. McCorkle for

assistance in plot maintenance.

Tab

le 1

. B

loo

m c

hara

cte

risti

cs f

or

blu

eb

err

y c

ult

ivars

in

1997-2

000 a

t th

e S

ou

thw

est

Researc

h a

nd

Exte

ns

ion

Ce

nte

r, H

op

e, A

rk. J

uli

an

da

y is

th

e a

dd

itiv

e

day o

f th

e y

ear

(Jan

. 30=

Ju

lian

day 3

0;

Feb

. 15=

Ju

lian

day 4

6 e

tc.)

.

Cultiv

ar

Bud s

well

(Julia

n d

ay)

10%

Blo

om

(Julia

n d

ay)

50

% B

loo

m (

Ju

lian

da

y)

1997

1998

1999

2000

Avg

1997

1998

1999

2000

Avg

1997

1998

1999

2000

Avg

Ge

org

iag

em

2 c

y10 c

30 b

c30 c

18 c

67 b

67 c

d48 c

62 d

61

d7

7 c

88

a6

2 b

73

bc

75

b

Legacy

2 c

7 c

22 d

32 c

16 c

56 c

63 d

51 c

63 d

58 d

69 d

76 b

59 b

68 c

68 c

O’N

eal

2 c

3 d

21 d

25 c

13 d

57 c

43 e

37 d

59 d

49

e7

2 c

d6

2 c

45

c7

7 b

64

c

Ozark

blu

e60 a

41 a

52 a

66 a

55 a

91a

90 a

89 a

87 a

89 a

97 a

94 a

98 a

94 a

96 a

Pre

mie

r3 c

11 b

c26 c

d25 c

16 c

69 b

83 b

58 b

67 c

69

b7

3 c

d8

9 a

63

b7

6 b

75

b

Sum

mit

13 b

18 b

35 b

48 b

29 b

66 b

72 c

60 b

74 b

68

b8

2 b

90

a6

5 b

77

b7

9 b

LS

D=

7z

LS

D=

5z

LS

D=

6z

y W

ithin

a c

olu

mn, num

bers

follo

wed b

y the s

am

e letter(

s)

are

not sig

nific

antly d

iffe

rent as d

ete

rmin

ed b

y least sig

nific

ant diffe

rence (

P=

0.0

5).

z L

SD

for

com

paring a

cro

ss y

ears

within

a v

ariety

(P

=0.0

5).

23

Horticultural Studies 2000

Table 2. Yields of blueberry cultivars in 1997-2000 at the Southwest Research and Extension Center, Hope, Ark.

Yield (lb/acre)

Cultivar 1997 1998 1999 2000 Avg. over years

Georgiagem 3049 cy

3935 d 3602 b 2942 b 3559 b

Legacy 7719 b 13,997 a 10,717 a 8792 ab 10,306 a

O’Neal 3821 bc 4887 cd 1714 b 1286 b 3161 b

Ozarkblue 15,382 a 13,350 ab 5061 b 6791 ab 10990 a

Premier 2921 c 3660 d 2934 b 9648 a 4871 b

Summit 3239 bc 9033 bc 6307 ab 4621 b 5592 b

LSD = 3547 z

y Within a column, numbers followed by the same letter(s) are not significantly different as determined by least significant difference (P=0.05).

z LSD for comparing across years within a variety (P=0.05).

Table 3. Berry weight for blueberry cultivars in 1997-2000 at the Southwest Research and Extension Center, Hope, Ark.

Avg. berry weight (g)

Cultivar 1997 1998 1999 2000 Avg. over years

Georgiagem 1.1 cy

1.0 c 0.9 c 1.0 c 0.9 c

Legacy 0.9 d 1.3 b 1.0 c 1.4 ab 1.1 bc

O’Neal 1.2 bc 1.5 a 1.4 b 1.5 a 1.4 a

Ozarkblue 1.4 a 1.3 ab 1.4 b 1.5 ab 1.4 a

Premier 1.2 bc 1.3 ab 1.5 a 1.2 b 1.3 ab

Summit 1.3 ab 1.5 a 1.4 ab 1.3 b 1.4 a

LSD = 0.22z

y Within a column, numbers followed by the same letter(s) are not significantly different as determined by least significant difference (P=0.05).

z LSD for comparing across years within a variety (P= 0.05).

24

AAES Research Series 483

‘GOLDNINE’, ‘GOLDJIM’, AND ‘ROYGOLD’

CLING PEACHES

John R. Clark1

IMPACT STATEMENT

Processing-quality cling peaches have been grown for many

years in Arkansas, with the majority of the production used for

baby food. The Arkansas Agricultural Experiment Station has

had a processing peach-breeding program since the 1960s, and

from this program two cultivars, ‘Allgold’ and ‘Goldilocks’,

were released in 1984. In 2000, three new cultivars were intro-

duced, ‘Goldnine’, ‘GoldJim’, and ‘Roygold’. All have good

processing quality and good bacterial-spot resistance. They also

expand the maturity season for processing-quality peaches.

These cultivars should expand options for processing peach

growers in Arkansas and other mid- to upper-southern states

and in other areas of the world with similar climatic conditions.

BACKGROUND

Arkansas has a long tradition of processing-peach produc-

tion, with production primarily in eastern Arkansas in the

Crowley’s Ridge area. The initial production consisted of culti-

vars of the ‘Babygold’ series, which were developed in New

Jersey. These cultivars were productive, but often had signifi-

cant infections of bacterial spot, and often developed red pig-

ment in the flesh, an undesirable trait which can contribute to

browning in the processed product. The Arkansas peach breed-

ing program was begun in the 1960s, and was a cooperative

effort of Dr. James N. Moore and Dr. Roy C. Rom. The pro-

gram included the objectives of high processing quality and

enhanced bacterial-spot resistance over existing cultivars. The

cultivars Goldilocks and Allgold provided new options for grow-

ers upon their release in 1984. The continued effort in process-

ing-peach improvement has resulted in three additional releases

from the program.

RESEARCH DESCRIPTION

‘Goldnine’ resulted from a cross of NJ 554367 x G17-5E

made in 1963 by Catherine Bailey and L.F. Hough of Rutgers

University, New Brunswick, N.J. The original seedling trees of

this cross were planted at the University of Arkansas Division

of Agriculture’s Fruit Substation at Clarksville in 1964 and the

original tree was selected in 1966 and tested thereafter as Ark.

9. ‘GoldJim’ resulted from a cross of Ark. 24 x NJC-70 made at

the Fruit Substation in 1971. The seedling trees of this cross

were planted at this location in 1972, and ‘GoldJim’ was se-

lected in 1977 and tested thereafter as Ark. 219. ‘GoldJim’ is

named in honor of Dr. James N. Moore. ‘Roygold’ resulted from

a cross of ‘GoldJim’ x Ark. 310 made in 1990 at the Fruit Sub-

station. The seedling trees of this cross were planted at this lo-

cation in 1991, and ‘Roygold’ was selected in 1993 and tested

thereafter as Ark. 560. ‘Roygold’ is named in honor of Dr. Roy

C. Rom.

Testing of these cultivars was at the Fruit Substation, [U.S.

Dept. of Agriculture (USDA) hardiness zone 7a; soil type

Linkerfine sandy loam], and ‘Goldnine’ and ‘GoldJim’ were

also tested at the Southwest Research and Extension Center,

Hope [USDA hardiness zone 8a, soil type Bowie fine sandy

loam]. In all testing, trees were trained to an open-center sys-

tem and pruned annually, spaced 18 ft between trees, fertilized

annually with either complete or nitrogen fertilizers, irrigated

as needed, and pests managed using a pest management pro-

gram typical for commercial orchards of the area including the

applications of fungicides and insecticides. No bactericides were

applied to evaluation plantings during testing of these cultivars.

Fruit thinning was done each year that a crop was present with

thinning to a distance of 6 to 8 in. between fruit prior to pit

hardening but after shuck split. Data were collected on these

trees from the time of selection until 2000. The following narrative

description provides information on the major characteristics

of these cultivars. A more detailed description as published in

HortScience volume 36, which includes detailed data, is avail-

able from the author upon request.

FINDINGS

‘Goldnine’ ripens on average 11 July at Clarksville, 10

days after ‘Allgold’ and 10 days before ‘Babygold 5’. ‘Goldnine’

yielded more than ‘Babygold 5’ and ‘Babygold 7’ at Hope.

Quality analyses indicate that it has processed quality compa-

rable to ‘Allgold’ and ‘Babygold 5’. In Arkansas tests, ‘Goldnine’

produced red pigment in the flesh in some years, but this has

not been a problem in tests in the cooler summer environment

of Michigan. ‘Goldnine’ has shown exceptional flower bud har-

diness and reliable cropping after cold winters in tests in Michi-

gan, Kentucky, and Arkansas. ‘Goldnine’ blooms 2 to 3 days

later than other similar processing peach cultivars. It has shown

less susceptibility to bacterial leaf spot than ‘Goldilocks’ or

‘Babygold 5’. ‘Goldnine’ was tested and sold to a limited ex-

tent by commercial nurseries as A-9 or Arkansas 9.

1 Department of Horticulture, Fayetteville

25

Horticultural Studies 2000

‘GoldJim’ ripens on average 19 July at Clarksville, 18 days

after ‘Allgold’ and 2 days before ‘Babygold 5’. It has signifi-

cantly out-yielded ‘Babygold 5’ and ‘Babygold 7’ in tests at

Hope. A major attribute of ‘GoldJim’ is its processed fruit qual-

ity. Over 28 years of evaluation, it has consistently rated among

the highest for processing attributes, including flesh color, fla-

vor, sugar content, and lack of red pigment in the flesh. In a

sensory panel evaluation, ‘GoldJim’ was rated highest of 11

cultivars for sweet and peachy flavor attributes. Winter bud

hardiness has been observed to be good for ‘GoldJim’. Follow-

ing test winters in Arkansas, flower bud survival of ‘GoldJim’

has been greater than for ‘Allgold’ and ‘Goldilocks’. It has been

less susceptible to bacterial leaf spot than ‘Goldilocks’ and

‘Babygold 5’.

‘Roygold’ is a very early-ripening processing clingstone

peach. It ripens on average 21 June, 10 days before ‘Allgold’

and 30 days before ‘Babygold 5’. ‘Roygold’ is among the ear-

liest ripening processing clingstone cultivars available. Yields

were not collected on ‘Roygold’, but crop load ratings have

been comparable to other processing peach cultivars. No pro-

cessing quality analysis has been conducted on ‘Roygold’, but

it is expected that processed quality will be very good based on

ratings for flesh color, firmness, flavor, and sugar content. Fruit

firmness is exceptional for ‘Roygold’, and it exceeded all com-

parison cultivars for this trait. Ratings for tree health of ‘Roygold’

were higher than for ‘Goldilocks’ and ‘Babygold 5’, mainly due

to the high level of resistance of ‘Roygold’ to bacterial leaf spot.

Budwood of ‘GoldJim’ and ‘Roygold’ is available from

John R. Clark, 316 Plant Sciences, Dept. of Horticulture, Univ.

of Arkansas, Fayetteville, AR 72701 (jrclark@uark.edu).

‘Goldnine’ is available in the commercial nursery trade and has

been marketed as Arkansas 9 or Ark. 9.

ACKNOWLEDGMENTS

We thank Curt Rom, Bryan Blackburn, Effie Gilmore,

David Gilmore, Patrick Byers, Robert Bourne, Jack Young, and

Stanley Brown for assistance in data collection during the evalu-

ation of these cultivars.

26

AAES Research Series 483

ANTIOXIDANT CONTENT OF FRUIT

CULTIVARS

John R. Clark1, Luke Howard2, and Steve Talcott2

IMPACT STATEMENT

Public awareness has developed in the area of health-promoting properties of foods, focusing not on traditionalnutritional value but rather on specific compounds in foods thatprovide benefits such as prevention of oxidative damage totissues associated with degenerative conditions. Berry fruits havebeen found to be among the foods highest in antioxidant capacity.The Arkansas Agricultural Experiment Station continues to bea world leader in fruit cultivar development, and antioxidantcontent of fruit cultivars developed in this program is beingevaluated. Evaluations of oxygen radical absorbance capacity(ORAC), total anthocyanins, and total phenolics were done in1999 on blackberry, blueberry, table grape, and nectarinecultivars released from the program. Overall, blackberries andblueberries were highest in ORAC value, followed by tablegrapes, and finally nectarines. The highest individual cultivarswithin each group included ‘Apache’ and ‘Navaho’ blackberries,‘Bluecrop’ and ‘Ozarkblue’ blueberry, ‘Jupiter’ grape, and‘Westbrook’ nectarine. However, the ORAC contents of thegrape and nectarine cultivars were substantially lower than thosefor the other fruits. Values for total anthocyanins and totalphenolics, related indicators of antioxidant capacity, generallyparalleled those for ORAC. The data provide the first look atthe antioxidant content of Arkansas-developed fruit cultivarsand provide information for use in evaluating genetic variationamong the cultivars.

BACKGROUND

Oxidative damage, catalyzed by reactive oxygen species,is implicated in numerous degenerative diseases of humans.Phytochemical and antioxidant content of foods is an emergingarea of research and public interest since antioxidants mayreduce the risks of degenerative disease. Fruits and vegetablesare excellent sources of antioxidant compounds, which mayprevent oxidative damage in the body. Fruits with highantioxidant value include blackberries and blueberries. The

Arkansas Agricultural Experiment Station has a productivecultivar development program in these and other fruit crops.Thus our investigation was initiated to evaluate the antioxidantcapacity of selected cultivars and to determine the geneticvariation that exists among cultivars of each crop.

RESEARCH DESCRIPTION

Fully ripe fruit samples of blueberries, blackberries, tablegrapes and nectarines were collected from several cultivars ofeach crop. Sample size ranged from 4 lb of fruit of the berries to20 lb of fruit of the grapes and nectarines. All of the fruits wereharvested from plants growing at the University of ArkansasFruit Substation, Clarksville. The fresh fruit samples weretransported to the Department of Food Science, Fayetteville,where they were stored at -20° C until analyzed. Frozen sampleswere homogenized and 5 g of homogenate was extracted with20 mL methanol:acetone:water:acetic acid (40:40:20:0.1).Samples were placed in a screw-cap vial to prevent solventevaporation and heated for 60 min in a 60° C water bath. Sampleswere allowed to cool, then homogenized for 1 min using atissuemizer. Extracts were filtered through Miracloth(Calbiochem, San Diego, Calif.) and kept frozen (-20° C) untilanalysis. Chemical analysis was conducted directly from theisolate extraction. Total soluble phenolics were quantified usingthe Folin-Cioclateu assay as described by Howard et al. (1996),and were expressed as chlorogenic acid equivalents. Totalanthocyanins were quantified using the pH differential methodof Wrolstad (1976) where 0.5 mL of the sample isolate wasadded to both 4.5 mL of pH 1.0 buffer and pH 4.5 buffer. Sampleswere maintained in the dark for 2 hours and the absorbancemeasured at 510 nm and 700 nm against a water blank. ORACwas measured using a modified version of Cao et al. (1995)using a Perkin-Elmer HTSoft 7000 Plus Bio Assay Reader(Norwalk, Conn.). The concentration of reagents were identicalto that of Cao et al. (1995) except for the working Trolox standard(Aldrich Chemical, Milwaukee, Wisc.), which was diluted to10 µM prior to use in the assay. Data in ORAC were expressedin µM Trolox equivalents per gram of fresh weight. Datarepresent the mean of duplicate samples from three 500 gcomposite samples of each genotype.

FINDINGS

Blueberry and blackberry cultivars were the highest of thefruits in ORAC value, averaging 39.4 and 36.0 µmol Troloxequivalents per gram of fruit (fresh weight), respectively.Variation also occurred among the genotypes of each fruit type,with ‘Apache’ blackberry and ‘Bluecrop’ blueberry having thehighest ORAC value in each grouping (Table 1). Conversely,the table grape and nectarine cultivars averaged 11.1 and 5.0µmol Trolox equivalents per gram of fruit (fresh weight),respectively. ‘Jupiter’ grape and ‘Westbrook’ nectarine werehighest in ORAC content, but the differences were minimalwithin each fruit type, especially among the nectarines.

Anthocyanin levels paralleled those of ORAC for the fruits,with blueberries and blackberries containing substantially higher

1 Department of Horticulture, Fayetteville2 Food Science Department, Fayetteville

27

Horticultural Studies 2000

levels of total anthocyanins than the grapes or nectarines (Table1). Average total phenolics for each fruit type were 5246 forblueberries, 3563 for blackberries, 4723 for table grapes, and1614 for nectarines, all expressed in chlorogenic acid equivalentsin mg/kg of fruit (fresh weight).

The data provided in this report are from a single year andrepresent only a small subset of genotypes available for eachfruit type. Research in this area continues, with a focus on thevariation in antioxidant level from year-to-year, withingenotypes, and among genotypes of several fruits. Theseadditional findings will provide further information for breedingcultivars with enhanced antioxidant levels in addition toidentifying antioxidant-rich cultivars.

LITERATURE CITED

Cao, G., C.P. Verdon, A.H.B. Wu, H. Wang, and R.L. Prior.1995. Automated assay of oxygen-radical absorbancecapacity with the COBAS FARA II. Clin. Chem. 41:1738-1744.

Howard, L.R., D.D. Braswell, and J. Aselage. 1996. Chemicalcomposition and color of strained carrots as affected byprocessing. J. Food Sci. 61:327-330.

Wrolstad, R.E. 1976. Color and pigment analysis in fruitproducts. AES, Oregon State University, Sta. Bull. 624.

Table 1. ORAC, total anthocyanin, and total phenolics for fruit cultivars, 1999 evaluations. Values are means of three

analyses of fruit from a single harvest.

Cultivar ORACz Total anthocyaninsy Total phenolicsx

Blackberry

Apache 52.4 1296 6346

Arapaho 38.7 1496 5340

Chickasaw 37.7 1125 5505

Choctaw 28.6 1007 4218

Kiowa 34.2 1305 5002

Navaho 50.1 1112 5754

Shawnee 34.2 1275 4556

Blueberry

Bluecrop 40.4 1061 3378

Duke 33.9 1723 3270

Ozarkblue 39.3 1561 3790

Summit 27.3 895 2874

Tifblue 39.1 1699 4506

Table grape

Jupiter 13.8 374 5450

Mars 11.8 279 4454

Neptune 8.4 NDw 3722

Venus 10.5 313 5266

Nectarine

Arrington 4.6 ND 1563

Bradley 5.1 ND 1567

Westbrook 5.3 151 1713

z ORAC=Oxidation-reduction absorbance capacity expressed as µmol Trolox equivalents per gram of fruit (fresh weight).

y Total anthocyanins=malvadin-3-glucoside equivalents in mg/kg of fruit (fresh weight).

x Total phenolics= chlorogenic acid equivalents in mg/kg of fruit (fresh weight).

w ND = none detectable.

28

AAES Research Series 483

‘WESTBROOK’, ‘ARRINGTON’, AND

‘BRADLEY’ NECTARINES

John R. Clark, James N. Moore, and Roy C. Rom1

IMPACT STATEMENT

Nectarine production in Arkansas is limited mainly to smallplantings for local sale. One of the major limitations for nectarineproduction in the state is a lack of adapted cultivars. ‘Westbrook’,‘Arrington’, and ‘Bradley’ are the first nectarine cultivarsreleased from the University of Arkansas peach and nectarinebreeding program. ‘Westbrook’ is a very early-ripening,melting-flesh, high skin-color nectarine with very good flavorfor the early season. ‘Bradley’ and ‘Arrington’ are also early-ripening, have non-melting flesh, and are characterized byenhanced fruit firmness and potential handling characteristicsassociated with this flesh type. All three cultivars have goodbacterial-spot resistance. These cultivars should expand optionsfor nectarine growers in Arkansas and other mid- to upper-southern states and in other areas of the world with similarclimatic conditions.

BACKGROUND

Arkansas has a long tradition of producing peaches, one ofthe most economically important horticultural crops. Nectarines,which are the same genus and species as peach, differ in thatthey do not have pubescence or “fuzz” on the skin. They havebeen produced to a limited extent in Arkansas. The majorlimitation in nectarine production in Arkansas has been ashortage of adapted cultivars. An effort was begun in the 1960sto develop nectarines cultivars adapted to Arkansas. These threenew nectarines are released to provide growers with new optionsin nectarine cultivar selection for pick-your-own orchards, localmarkets, or shipping markets.

RESEARCH DESCRIPTION

‘Westbrook’ resulted from a cross of Ark. 172 x Ark. 176

made in 1977 at the University of Arkansas Fruit Substation,

Clarksville. The original tree of ‘Westbrook’ was selected in

1980 and was tested as Ark. 236. ‘Westbrook’ is named for Mr.

Cole J. Westbrook, resident director of the Fruit Substation from

1948 through 1976. ‘Arrington’ resulted from a cross of Ark.

178 x Ark. 232 made in 1984 at the Fruit Substation. The origi-

nal tree was selected in 1989 and was tested as Ark. 417.

‘Arrington’ is named for Mr. Gene Arrington, resident director

of the University of Arkansas Peach Substation, Nashville, from

1948 through 1987. ‘Bradley’ resulted from open pollinated seed

gathered from a population of a cross of Ark. 190 x Ark. 178

made in 1980 at the Fruit Substation. The original tree was se-

lected in 1988 and was tested as Ark. 402. ‘Bradley’ is named

for Dr. George A. Bradley, head of the Horticulture Department

at the University of Arkansas from 1968 through 1991.

Testing of these cultivars was at the Fruit Substation, [U.S.

Dept. of Agriculture (USDA) hardiness zone 7a; soil type Linker

fine sandy loam]. In all testing, trees were trained to an open-

center system and pruned annually, spaced 18 ft between trees,

fertilized annually with either complete or nitrogen fertilizers,

irrigated as needed, and pests were managed using a pest man-

agement program typical for commercial orchards of the area,

including the applications of fungicides and insecticides. No

bactericides were applied to evaluation plantings during testing

of these cultivars. Fruit thinning was done each year that a crop

was present with thinning to a distance of 6 to 8 in. between

fruit prior to pit hardening but after shuck split.

A more detailed description as published in volume 36 of

HortScience, which includes detailed data, is available from the

author upon request.

FINDINGS

‘Westbrook’ is a very early-ripening (9 June average at

Clarksville, Ark., three weeks before ‘Redhaven’), melting-flesh

nectarine. It has excellent flavor for a very early ripening nec-

tarine. The fruit has mostly red skin color, and is medium-firm

and medium-sized. Crop loads were rated good on ‘Westbrook’,

although yields were exceeded by ‘Bradley’ and ‘Arrington’ in

trials. Trees were free of bacterial spot in almost all years of

evaluation (the fruit was always free of spot and the leaves had

a very slight infection if any was seen at all). In some years,

‘Westbrook’ has been observed to have some skin breakdown

on fully ripe fruit following rainfall, therefore this needs to be

considered in fruit handling and marketing. ‘Westbrook’

bloomed on average 25 March at Clarksville, 4 to 6 days later

than other nectarines growing at this location. Consistent crop-

ping was experienced with ‘Westbrook’ in all years except when

spring freezes or frosts eliminated the crop on all nectarines or

peaches. ‘Westbrook’ is envisioned to be a very early-season

nectarine for local markets.

1 All authors are associated with the Department of Horticulture, Fayetteville.

29

Horticultural Studies 2000

‘Arrington’ is also early, ripening 24 June at Clarksville.

The fruit is medium in size with good skin color (good mix of

red and orange/yellow background color). The fruit has non-

melting, all-yellow or gold flesh, lacking red pigment, with a

mild nectarine flavor. Slight bacterial spot has been seen on

leaves of ‘Arrington’ trees in some years, but not on fruit. Trees

are very productive and have been reliable producers at

Clarksville, and ‘Arrington’ has been one of the higher yielding

nectarines in trials. Average full bloom date at Clarksville was

20 March for ‘Arrington’, 2 days earlier than ‘Bradley’ and ‘Red

Gold’. The non-melting flesh provides very firm fruit at or near

maturity.

‘Bradley’ ripens on average 29 June at Clarksville, near

‘Redhaven’ peach season. Trees of ‘Bradley’ are very produc-

tive, and bacterial spot has seldom been seen on leaves or fruit.

In fact, ‘Bradley’ is one of the cleanest trees for bacterial spot

ever observed at the Fruit Substation. Average bloom date at

Clarksville was 22 March, between ‘Arrington’ and ‘Westbrook’.

Fruits have attractive skin color (good mix of red and orange/

yellow background color), all-yellow or gold flesh, are medium

to large, and have non-melting flesh. Flavor is good and in-

cludes a significant component from its processing-peach par-

entage. The non-melting flesh provides excellent fruit firmness

at or near maturity.

An application for a U.S. plant patent has been filed for all

three cultivars. A list of nurseries licensed to propagate and sell

these cultivars can be obtained from John R. Clark, 316 Plant

Science, Dept. of Horticulture, Univ. of Arkansas, Fayetteville,

AR 72701 (jrclark@uark.edu).

ACKNOWLEDGMENTS

We thank Curt Rom, Bryan Blackburn, Effie Gilmore,

David Gilmore, Patrick Byers, Robert Bourne, Jack Young, and

Stanley Brown for assistance in data collection during the evalu-

ation of these cultivars.

30

AAES Research Series 483

DETERMINATION OF CHILLING

REQUIREMENT OF ARKANSAS THORNLESS

BLACKBERRY CULTIVARS

Chrislyn A. Drake and John R. Clark1

IMPACT STATEMENT

Chilling requirement is commonly thought of as the period

of time that a woody perennial plant must be exposed to tem-

peratures under 7° C (45° F) for normal budbreak to occur the

following year. If this requirement is not met, budbreak (and

consequently flowering, fruiting, and plant growth) may be re-

duced. Little research has been done to determine the chilling

requirement for blackberry cultivars. However, field observa-

tions from areas where low amounts of chilling occur indicate

that ‘Navaho’ requires more hours of chilling than ‘Arapaho’.

The objective was to determine a method for measuring chill-

ing requirement using whole plants of two blackberry cultivars,

Arapaho and Navaho. One-year old, bare-root plants were placed

in a cold chamber at 3° C (37° F) to accumulate chill and were

removed at 100-hour intervals up to 1000 hours. The plants were

placed in a greenhouse and budbreak data were recorded. Data

indicated that the chilling requirement for ‘Arapaho’ is between

400 and 500 hours. For ‘Navaho’, the data indicated the chill-

ing requirement was between 800 and 900 hours. These data

support previous observations and indicate the method used was

successful in determining chilling requirement for blackberries.

BACKGROUND

Most temperate-zone perennial woody plants require some

degree of rest in order for the buds to break uniformly the fol-

lowing season. This rest period is a type of safety mechanism

that keeps buds from breaking under the wrong environmental

conditions, such as warm periods in the middle of the dormant

season. Rest period is defined as the duration that a plant must

be exposed to cold temperatures under 7° C (45° F) in order for

normal shoot or flower development to occur in the spring

(Ryugo, 1998). Chilling requirement is the amount of cold

needed to satisfy the rest period (Ryugo, 1998).

No formal research has been done on blackberry, a widely-

grown horticultural crop in Arkansas and other areas of the

United States. This interest in blackberries is partially a result

of the release of new blackberry cultivars Choctaw, Navaho,

Arapaho, Kiowa, and Shawnee by the University of Arkansas.

However, growers in southern regions of Arkansas and in sub-

tropical climates have encountered problems with poor budbreak

in some of these cultivars, presumably because the chill require-

ment was not met. Most of the chilling information on Arkan-

sas blackberries has been generated by researchers and growers

in southern areas of the US (such as coastal Mississippi and

Florida) or other countries with warm climates. For example,

the thornless cultivar Navaho has been observed to have poor

budbreak in southern Mississippi (Creigton Gupton, personal

communication, USDA, Poplarville, Miss.) and Florida (Peter

Andersen, personal communication, Univ. of Fla., Monticello),

presumably due to lack of chilling. The cultivar Choctaw has

been found to be the most adapted of the Arkansas cultivars in

Mexico and South Africa, which are areas that receive little to

no chilling during the winter (J.N. Moore, personal communi-

cation). These observations suggest that there is variation in

chill requirement for blackberry cultivars.

Due to observed differences in chilling requirement of

blackberries in Arkansas and elsewhere, the objective of the

study was to determine a method for measuring chilling require-

ment of blackberry cultivars using whole plants in a controlled

environment. As lack of chilling rarely occurs in Arkansas, it

was necessary to develop a method where the amount of chilling

could be controlled and the differences in response measured.

RESEARCH DESCRIPTION

One-year old ‘Arapaho’ and ‘Navaho’ bare-root plants were

field-dug from a local nursery on 26 Oct. 1999 following the

first killing frost of the season. Upon arrival in Fayetteville, the

plants were heeled-in in containers filled with mulch and placed

in a cold chamber at 3° C (37° F) in darkness. Ten single-plant

replications were removed at 100-hour intervals up to 1000

hours. The plants were cut back to approximately 0.6 meter (2

ft) single cane lengths and potted in 4 L (1 gal) pots.

In order to force budbreak, the plants were then transferred

to a heated greenhouse with a daily minimum temperature of

15° C (59° F) and daily maxima range of 17-22° C (63-72° F).

The plants were arranged in a completely randomized design.

Budbreak data was recorded on a weekly basis. A bud was con-

sidered broken when the first leaf became visible as it unfolded

from the bud. Data for budbreak after five weeks for each 100-

hour chilling treatment were analyzed as a two-factor factorial

(two cultivars and ten chilling treatments) by SAS and means

separated by least significant difference (LSD) (P=0.05).

1 Both authors are associated with the Department of Horticulture, Fayetteville

31

Horticultural Studies 2000

FINDINGS

Data analysis showed a significant interaction of cultivar

and chilling treatment, F-test P≤0.01. Based on this finding,

main effect means for each cultivar are presented in this discussion.

Budbreak levels were very low for ‘Arapaho’ for the 100

through 400 hour chilling treatments (Fig. 1). At 500 hours,

budbreak increased from 4% to 24%, a major increase which

reflects a probable chilling requirement of between 400 and 500

hours for this cultivar. There was a slight decrease in budbreak

at 600 hours. Due to poor plant health these plants did not break

buds until the sixth week. Budbreak continued to increase with

increased chilling but at no treatment interval was there a simi-

lar or significantly higher budbreak than at the 400 to 500 hour

interval.

Unlike ‘Arapaho’, ‘Navaho’ exhibited rather high levels of

budbreak at the early chill-hour treatments. (Fig. 2). ‘Navaho’

may not fully enter into dormancy until it has been exposed to

chilling temperatures for some time. However, budbreak was

low (5% at 800 hours) until the 900 hour chilling treatment. At

this level, budbreak increased from 5% to 33%, which was very

similar to the large increase in percent budbreak at 500 hours

for ‘Arapaho’. This increase reflects a probable chilling require-

ment of between 800 and 900 hours for ‘Navaho’. Budbreak

did increase at the 1000-hour level but was not as large as the

increase in budbreak at the 900-hour level. The 25% budbreak

at 500 hours was a substantial variation in budbreak trend when

compared to adjacent chill periods. This can be attributed to the

failure of five of the plants in this chill treatment to break bud

due to poor plant health. Of the surviving five, two had extraor-

dinarily high percent budbreak, skewing the results to the un-

usually high level.

The data correlate with previous field observations from

Hope, Ark., and other areas of the southern United States. Due

to the correlation between field observations and the results of

the study, the whole-plant system appears to be a valid method

of evaluating chilling requirement for blackberry cultivars. Other

cultivars can now be evaluated for chilling requirement, allow-

ing growers in areas where low levels of chilling are accumu-

lated to know which cultivars are suited for their area.

LITERATURE CITED

Ryugo, K. 1998. Fruit culture: Its science and art. John Wiley

and Sons. London.

ACKNOWLEDGMENTS

The authors thank Simmons Plant Farm, Mountainburg,

Ark., for donation of the plants used in this study. Also, appre-

ciation is expressed to the Bumpers College of Agricultural,

Food and Life Sciences for grant support to conduct this inves-

tigation. Finally, thanks to Andy Allen, research specialist in

fruit crops, for his assistance.

32

AAES Research Series 483

Figure 1

0

10

20

30

40

50

60

70

100 200 300 400 500 600 700 800 900 1000

Hours of chilling

Pe

rce

nt

bu

db

rea

k

aa

a

a

bc

ab

cd

bcd

Figure 2

0

5

10

15

20

25

30

35

40

45

50

100 200 300 400 500 600 700 800 900

Hours of chilling

Pe

rce

nt

bu

db

rea

k

ab

ab ab

a

abc

aa

Fig. 1. Budbreak of ‘Arapaho’ thornless blackberry after five weeks of placement in a heated greenhouse following

chilling of 100 through 1000 hours at 3° C. Means not followed by the same letter are significantly different as

determined by LSD (P=0.05).

Fig. 2. Budbreak of ‘Navaho’ thornless blackberry after five weeks of placement in a heated greenhouse following

chilling of 100 through 1000 hours at 3° C. Means not followed by the same letter are significantly different as

determined by LSD (P=0.05).

33

Horticultural Studies 2000

THE EFFECTS OF TRANSITIONING A MATURE

HIGH-DENSITY ORCHARD FROM STANDARD

HERBICIDE GROUND-COVER MANAGEMENT

SYSTEM TO ORGANIC GROUND-COVER

MANAGEMENT SYSTEMS

John B. Fausett and Curt R. Rom1

IMPACT STATEMENT

Ground-cover types in apple orchards have tremendous ef-

fects on moisture conservation, weed populations, surface root

growth, soil surface temperature, overall soil tilth, and tree

growth and productivity. With the expansion of organic fruit

production in the U.S., and the development of the Federal Or-

ganic Standards, more information on horticultural production

techniques appropriate for transition and organic orchards is

needed. A study was conducted on the effects of transitioning a

mature orchard from a traditional herbicide strip system to an

organic ground cover system. Ground-cover management had

significant effects in the first season on soil surface moisture

content, root growth in the top 6 in. of soil, yield and fruit

quality.

BACKGROUND

Orchard weeds are typically controlled using herbicides.

Since herbicide contamination is a prevalent concern among

today’s environmentally and health conscious consumers, al-

ternative weed control measures are needed. In recent years,

much interest in alternatives to orchard herbicides has devel-

oped including mechanical control by cultivation, torching, or

use of various mulches. Mulching is a viable alternative for

weed control and may provide other benefits to the production

system. A wide array of mulches are available. Materials such

as chopped hardwood, shredded office paper, and sheets of black

plastic are potential materials and have been used with very

little research data demonstrating their usefulness. The best

one for use in an apple orchard will depend on climatic factors

and availability.

Mulching, especially organic mulching, can influence many

soil properties. According to Janick (1986), apple trees form a

network of fibrous feeder roots in the top 6 in. of soil, which is

responsible for increased absorption of water and nutrients. This

uppermost layer of soil is the area where mulch type affects the

biotic and abiotic properties of the underlying soil. Brady and

Weil (1999) suggest that temperature buffering, moisture con-

servation and increased biological diversity could result from

the application of organic mulches. Because of its ability to

moderate soil temperature, act as a source of organic carbon for

soil organisms, reduce evaporation and improve infiltration,

mulching for organic weed control may be superior to herbi-

cide applications.

RESEARCH DESCRIPTION

A study was conducted to evaluate the effects of changing

a mature orchard with traditional herbicide strip weed preven-

tion to a mulched ground cover. The orchard was planted in

1992 with three apple cultivars, Gala, Jonagold and Braeburn,

planted on ‘M9’ rootstocks, 1.25 m x 3.0 m. The orchard was

managed using minimal insect and disease treatments with con-

ventional pesticides.

On 5 June 2000, a completely randomized design of six

replications of single-tree experimental units with one of four

ground cover treatments was applied to the orchard; 1) conven-

tional herbicide use, 2) woven black plastic landscape fabric, 3)

coarse hardwood bark, 4) shredded office paper. All treatments

were applied in a square (1.25 m x 1.25 m) underneath the

dripline of the tree. The herbicide treatments were sprayed

two to three times a season with a paraquat, oryzalin, and si-

mazine herbicide mix to prevent weed emergence and growth.

Soil nutrients, bulk density, and pH were determined prior to

ground cover application in order to provide baseline data so

that later changes by different treatments could be detected.

Soil moisture readings were taken weekly at two points

under each treatment tree canopy with a Theta-probe Type ML2x

(Delta-T Devices, Cambridge, England), from 28 June to 1 Nov.

2000. The mulch was removed before each soil moisture deter-

mination and replaced immediately after. On 7 July 2000 a

series of root capture tubes were added to all plots containing

‘Jonagold’. Each tree contained two 334.5 cm3 cores (PVC

pipe 15 cm x 5 cm) with twelve 2.5 cm diameter holes and

wrapped with a 2 mm mesh. Appropriate amounts of soil were

removed from each side of a tree and cores were placed in the

holes. Once the cores were installed, the soil was returned and

mulch was then placed over the core area. Root capture tubes

were extracted 1 Nov. 2000 and root density (mg roots/cm3

soil) measured. Fruit on trees was harvested (kg/tree) at matu-

rity and fruit size and quality of a 10 fruit/tree sub-sample evalu-

ated.

All data were analyzed by analysis of variance and means

separations were determined by least significant difference

(LSD) (P≤0.05).

1 Both authors are associated with the Department of Horticulture, Fayetteville.

34

AAES Research Series 483

FINDINGS

Every mulch type had weed population densities less than or

equal to that of an herbicide treated strip (data not presented).

The black plastic was the most effective weed deterrent with no

weeds. The hardwood mulch had an average value of 1.3 weeds/

m2, while the white paper mulch and the traditional herbicide

strip average weed population densities were 1.5 weeds/m2. All

three types of mulches and the herbicide strip worked well for

controlling weeds.

Mulch significantly affected fine root (roots <10mm diam.

located 0-150 mm below soil surface) density underneath the

tree canopy (Fig. 1). The root density beneath the hardwood

treatment was significantly higher then the other treatments.

The white paper and herbicide strip treatments were not signifi-

cantly different from each other, however they were signifi-

cantly higher then the black plastic treatment which had the

lowest root density.

An increase in soil moisture content was observed for each

mulching treatment compared to the unmulched, herbicide strip

treatment during mid- to late-summer, for days of the year 222-

264 (Fig. 2). The herbicide strip had soil-surface moisture con-

tent values less than or equal to that of all mulching types. There

were differences between the moisture content values; how-

ever, the differences were not statistically significant.

Fruit yield was not significantly affected by ground-cover

treatment for any of the cultivars (Table 1). However, the black

plastic treatments produced significantly smaller fruit soluble

solids for the ‘Gala’, and smaller fruit weight for ‘Jonagold’

and ‘Braeburn’. The black plastic treatment for ‘Gala’ was

also the only treatment with increased average fruit firmness

and a decrease in average soluble solids.

This was the initial establishment year of the study. It is

expected that more significant changes may occur as the study

continues and the rhizosphere equilibrates to the ground cover

treatment. Because of differences in root density and soil mois-

ture observed this year, nutrient content, flower bud formation,

tree growth, and other growth variables are expected to change

in the upcoming seasons.

In the first year of application of alternative ground covers,

some significant effects occurred. It is anticipated that the more

profound affects on tree growth and productivity may manifest

themselves in future seasons. However, some immediate ben-

efits and problems of these alternatives to herbicides were ob-

served in the initial season of transition.

LITERATURE CITED

Brady, N.C. and R. R. Weil. 1999. The Nature and Properties

of Soils. Prentice Hall, Upper Saddle River, N.J.

Janick, J. 1986. Horticulture Science. W. H. Freeman and Com-

pany, New York.

35

Horticultural Studies 2000

Table 1. The effect of ground-cover management treatments on yield and fruit quality of 3 apple cultivars, Fayetteville,

Ark., 2000. All trees were grafted on ‘M9’ rootstocks and in their ninth season of growth.

Avg. Soluble

fruit solids Starch Fruit Firmnessx

Yield/tree weight (%) ratingz juice pH (kg)

Treatments (kg) (g)

Gala

Black plastic 8.4 ay 123 a 14.8 b 4.7 a 4.2 a 7.4 a

Hardwood 7.6 a 158 a 15.1 a 5.3 a 4.2 a 7.1 a

Herbicide 9.9 a 146 a 15.4 a 5.0 a 4.3 a 7.2 a

White paper 6.6 a 143 a 16.4 a 5.2 a 4.1 a 7.3 a

LSD 3.6 43 0.8 1.6 0.5 0.9

Jonagold

Black plastic 7.7 a 157 b 14.8 a 3.4 a 3.0 a 8.8 a

Hardwood 8.2 a 251 a 14.1 a 3.5 a 3.2 a 8.4 a

Herbicide 5.5 a 226 a 14.4 a 3.1 a 3.1 a 8.7 a

White paper 5.9 a 226 a 14.6 a 4.0 a 3.3 a 8.2 a

LSD 4.1 50 1.0 1.8 0.6 0.9

Braeburn

Black plastic 2.6 a 121 c 13.8 a 6.3 a 3.8 a 10.4 a

Hardwood 1.2 a 189 b 13.1 b 6.1 a 3.5 a 8.6 ab

Herbicide 1.6 a 154 bc 13.5 ab 6.6 a 3.8 a 9.8 a

White paper 2.2 a 229 a 14.1 a 7.4 a 3.6 a 7.9 b

LSD 3.2 39 0.7 1.4 0.4 1.8

z Starch rating on a 0-12 scale – 0 = complete cortical starch, 12 = no cortical starch.

y Mean separation within cultivar and within a variable determined by LSD; means followed by a different letter are significantly different (P< 0.05).

x Pressure measured with a Penetrometer (Wagner Fruit Pressure Tester) with a 1.10 cm tip.

36

AAES Research Series 483

Fig. 1. Effect of ground-cover management treatments on root density for ‘Gala’, ‘Jonagold’ and ‘Braeburn’ apples

(cultivars pooled). Mean separation within ground cover determined by LSD; means followed by a different letter are

significantly different (P<0.05).

Fig. 2. Effect of ground-cover management treatments on soil moisture (50-75 mm depth) underneath tree canopy.

Means from each sample date were not significantly different as determined by t-test (P<0.0001).

37

Horticultural Studies 2000

SIZE CONTROL OF PEACH TREES USING

COPPER-IMPREGNATED POLYPROPYLENE

FIBER GROWBAGS: A GREENHOUSE STUDY

Scott Maxwell and Curt Rom1

IMPACT STATEMENT

Size control of peach trees may be achieved by restriction

of the root zone. The level of tree size control can be dependent

upon rooting volume. A greenhouse study was conducted to

evaluate the effects of root confinement with copper-treated

fabric containers of various volumes on the physiological be-

havior of young peach trees. Total vegetative growth decreased

linearly with decreasing rooting volume. Decreasing soil vol-

ume was also found to increase the percentage of fine roots.

These findings confirm that growth control is achieved by root

restriction, and the effect of various soil volumes may have

implications and applications in peach production systems.

BACKGROUND

Effective strategies of tree size control are currently un-

available to peach producers. Adapted dwarfing rootstocks are

not available (Rom, 1983). Physiological factors that can be

utilized for growth control include water deficit stress and crop

load. Physical or mechanical alteration of peach trees can also

be an effective method of reducing vegetative growth. Methods

include pruning, training, root pruning, girdling, and root re-

striction.

Root restriction of peach trees has been found to increase

fruiting precocity and yield efficiency in early tree life

(Williamson and Coston, 1990). Root confinement could also

add to orchard efficiency by reducing pruning requirements,

and increasing irrigation and fertilization efficiency. Limited

research is available that deals with root restriction of various

volumes (Myers and Savelle, 1990).

Fabric containers that allow a free exchange of air and wa-

ter with the surrounding soil have been used in field nursery

production. A problem has been root escape through the con-

tainer. However, copper compounds impregnated in the fabric

may solve the root escape problem. The objective of this study

was to examine the effects of various rooting volumes on the

physiological behavior of young peach trees in an optimal grow-

ing environment.

RESEARCH DESCRIPTION

‘Bounty’ peach trees were planted in copper-treated non-

woven polypropylene fiber containers (Texel, Inc., Quebec,

Canada) of three different volumes (26.5 L -small, 37.9 L -

medium, and 56.9 L -large). These containers were treated with

6 g/m2 of copper hydroxide on the interior. The fabric contain-

ers were planted in large (114 L) plastic containers with drain-

age holes. Sunshine™ (mix #2) with 20% added perlite for addi-

tional porosity was used both inside and outside of the fabric

containers. Optimal environmental conditions were maintained

throughout the 4-month study (1 April - 1 Aug. 2000). Day length

was maintained at 14 hours with an average daytime tempera-

ture of 28° C. The trees were fertilized and irrigated equally the

entire 4-month period. A completely randomized design was

utilized using nine replications of three treatments and was ana-

lyzed by SAS.

Measurements began 5 weeks after the bare-root trees were

planted and placed in the greenhouse. Carbon dioxide assimila-

tion (A), stomatal conductance (gs), and evapotranspiration (Et)

were measured weekly using a CIRAS-1 (P.P. Systems, Inc.)

portable infrared gas analyzer (IRGA) and a Parkinson leaf cu-

vette (2.5 cm2). The measurement environment maintained a

CO2 concentration of 350 ppm, an average temperature of 31°

C, 25% humidity, and 1000 micromoles/mm2/sec. of photosyn-

thetically active radiation (PAR). Sample leaves for measure-

ment on each tree were selected by choosing two main scaffold

branches and sampling a leaf 6 to 8 in. from the terminal end of

the branch. Trunk cross-sectional area (TCSA) measurements

were made every 2 weeks, and volumetric soil moisture was

measured at 4-day intervals using a theta-probe type ML2x

(Delta-T Devices Ltd., Cambridge, England). Vegetative growth

was analyzed at the end of the 4-month study by measuring

root and shoot dry weights, number of shoots, total shoot length,

leaf number/tree, total leaf area, average leaf size, and specific

leaf weight (g/cm2). Additional root measurements were taken

at the interface of the fabric container and the interior of the

fabric container (the root ball). The fabric was carefully peeled

from the root-ball to analyze roots at the interface. The number

of large and small roots and the location of those roots were

measured at the soil-bag interface. Placing a rectangular grid

on two sides of each root ball and counting the density of large

and fine roots in each square down the grid provided root mea-

surements indicating the location of roots at the interface. The

grid consisted of a strip of two squares that ran from the top of

the root-ball to the bottom, with a total of eight squares on the

grid. The total dry weight of roots that penetrated the fabric

container was also measured.

1 Both authors are associated with the Department of Horticulture, Fayetteville.

38

AAES Research Series 483

FINDINGS

The data presented represents growth after the 4-month

study was completed (Table 1). Small container (26.5 L) treat-

ments affected the growth of both the roots and shoots of the

trees. There was a linear correlation between rooting volume

and shoot dry weight, total shoot length, leaf number/tree, leaf

area, TCSA, and root dry weight (Table 1). Trunk cross-sec-

tional area is a proven indicator of total aerial plant growth

(Westwood, 1986). The root: shoot ratio was consistent across

all root volume treatments (Table 1). These results are consis-

tent with the functional equilibrium that has been proven to exist

among many plant species.

The percentage of fine-root dry weight compared to the

dry weight of the entire root system was higher in the small

containers than in the medium and large containers (Table 1).

Root pruning at the copper-treated interface is likely a reason

for the increased production of fine roots. Senescing roots were

observed at the copper-treated interface. Root pruning has been

found to stimulate new root growth (Ferree et al., 1992). Re-

striction of the lateral roots may also induce a physiological

response to stimulate branching and new root growth. Small

volume treatments also had a higher density of fine roots at the

root ball-fabric container interface in the bottom half of the bag.

Evapotranspiration was significantly reduced in the small

containers from the two larger sizes (Fig. 1). The difference

was not observed between the treatments until the twelfth week

of the study. Stomatal conductance among the small container

treatments became significantly less than the other two treat-

ments after the fourteenth week of the study (Fig. 1). Assimila-

tion was not affected by container volume within the sixteen-

week study (Fig. 1). The shoot growth of the trees in the small

container treatment was reduced compared to large container

treatments within 6 weeks. The continuous high rate of physi-

ological activity among the small container treatment, despite

lack of shoot growth, was likely due to the increased activity of

the root system reflected by the production of fine roots.

Volumetric soil moisture measurements were relatively

similar among the three treatments (data not presented). Soil

drying occurred more rapidly inside the fabric container com-

pared to outside of the container. The ability of the peach roots

to utilize soil moisture outside of the fabric container was some-

what impeded. The water use of all three treatments was dra-

matically increased from the beginning to the end of the experi-

ment, and the level of soil drying between irrigation intervals

was equal across all treatments (data not presented). The level

of soil drying between irrigation intervals was equal across all

soil-volume treatments.

LITERATURE CITED

Ferree, D.C., S.C. Myers, and J.R. Schupp. 1992. Root pruning

and root restriction of fruit trees-current review. Acta

Horticulturae. 322:153-166.

Myers, S.C. and Savelle, A. 1990. Effect of in-ground fabric

containers on growth and fruiting of peach and apple. Proc.

Southeastern Prof. Fruit Workers Conf. 4:1-3.

Rom, R.C. 1983. The peach rootstock situation: an international

perspective. Fruit Var. J. 37:3-14.

Williamson, J.G. and D.C. Coston. 1990. Planting method and

irrigation rate influence vegetative and reproductive growth

of peach planted in high density. J. Amer. Soc. Hort. Sci.

115:207-212.

ACKNOWLEDGMENTS

The authors extend thanks to Griffin Chemical Co. and Texel

Products for grant support of this project.

Fig. 1. The effect of three different volumes

of Cu-impregnated nonwoven polypropylene

containers on gas exchange of ‘Bounty’/Lovell

peach trees grown in a greenhouse: Assimilation

(A); Conductance (gs); Evapotranspiration (Et).

S= 26.5 L containers, M= 37.9 L containers,

L= 56.9 L containers.

39

Horticultural Studies 2000

Table 1. The effect of root confinement by three volumes of copper-impregnated fiber containers on growth of

‘Bounty’ peach in a greenhouse, Fayetteville, Ark., 2000.

Container Shoot Shoot Fine root Total root

volume TCSAZ Leaf area length weight weight weight Root:shoot

(L) (mm2) Leaf no. (cm2) (cm) (g) (g) (g) ratio

26.5 203.6 558 435 929 151.6 33.9 124.5 0.82

37.9 292.6 594 639 1033 173.8 34.2 148.8 0.85

56.9 363.0 631 1143 1089 215.5 35.4 173.4 0.80

Regression analysisy

r2 0.33* 0.24* 0.19* 0.29* 0.30* 0.16* 0.31* ns

Z Trunk cross sectional area at 2.5 cm above graft union.

y * = Significant at P=0.05; ns= not significant.

40

AAES Research Series 483

EARLY PERFORMANCE OF PEACH

ROOTSTOCKS FOR ARKANSAS

Curt R. Rom1

IMPACT STATEMENT

Peach orchard systems are being studied to provide infor-

mation that Arkansas fruit growers can use to improve economic

sustainability with earlier and increased production. Aspects of

peach orchard systems for which studies have been established

include extensive testing of peach rootstocks, development of

new rootstocks, and the testing and evaluation of orchard plant-

ing densities and tree training methods. Whereas tree density in

apple orchards is dictated by size-controlling rootstocks, there

is currently a lack of size-controlling and adaptable rootstocks

for peach. This study reports the early performance of potential

rootstocks for Arkansas, which is especially critical to produc-

tion and returns from the orchard.

BACKGROUND

For modern orchards to be profitable, the orchard must pro-

duce fruit quickly. Early production allows the grower flexibil-

ity to change cultivars as demanded by the consuming public,

to replant older low-productivity blocks, to return money to the

operation, and/or to pay loans for the establishment of the new

orchard. The most commonly used peach rootstocks have been

seedling rootstocks produced as refuse from clingstone peach

processing industries. New peach rootstocks are being intro-

duced worldwide and have been imported into the U.S. Some

may be entering the nursery market in the next few years. It is

important to test these stocks to evaluate surviability and pro-

ductivity in the Arkansas environment.

RESEARCH DESCRIPTION

The Arkansas Agricultural Experiment Station participates

in the NC-140 National Uniform Test of Rootstocks and

Interstems for Pome and Stone Fruits project. The 1994 Peach

Rootstock trial reported herein is one of 17 locations where this

uniform trial is planted. There are two purposes for this trial.

The first is to determine local adaptability of peach rootstocks.

The second, using the multiple sites of the national trial, is to

determine which rootstocks are regionally or nationally adapted.

The trial was planted at the University of Arkansas Divi-

sion of Agriculture’s Fruit Substation at Clarksville on a Linker

fine sandy loam soil with a 3-8% slope. The 1994 trial was

planted in the same location as a previous trial (1984-1993)

with only a 9 month renovation period for preparation of the

site for replanting. Trees for the 1994 trial were planted in late

May, 1994.

Trees on 14 rootstocks (Table 1) with ‘Redhaven’ as the

scion were planted at 6 m between rows, 5 m between trees and

trained to a standard open center vase (inverted cone) form with

3-5 scaffold limbs per tree. Trees with the rootstock cultivars

Lovell and Bailey were considered control trees as they are the

standard recommendations for Arkansas orchards. Trees re-

ceived regular maintenance for pest and weed control and

supplemental irrigation was provided with a drip emitter sys-

tem with one emitter per tree. An over-application of herbicide

in 1997 caused leaf yellowing and premature leaf drop. Fur-

ther, droughts in late summer of 1995 and 1998 resulted in some

late- season (August - September) water stress and premature

defoliation. Trees were not allowed to crop in the first 3 years

(1994-96).

Annually, tree growth variables of tree height, tree width,

and trunk cross-sectional area (TCSA) were measured after 50%

defoliation (approximately 15 Oct). Each spring the date of full

bloom was estimated. First harvest of fruit occurred when ap-

proximately 10% of the fruit on trees were considered firm-ripe

and had lost green ground color. Fruit were harvested twice;

occasionally trees required three harvests. Yields represent

pooled totals from all harvests. At each harvest a 50-fruit ran-

dom sample was collected and weighed to determine average

fruit weight. Average fruit weight presented was averaged size

of all harvests. From yields and TCSA, an estimate of tree pro-

duction efficiency (amount of fruit produced relative to the veg-

etative growth of the tree) was calculated as yield/TCSA. The

study was planted in a randomized complete block design with

eight single-tree replications blocked by row. Analysis of vari-

ance and mean separation analysis was performed to assess dif-

ferences among performance variables.

FINDINGS

Survival of most stocks in the first seven seasons was good.

Single trees of ‘Lovell’ and ‘Nemaguard’ died, and 50% of the

trees of ‘TaTao 5’ died while all trees of all other rootstocks

1 Department of Horticulture, Fayetteville.

41

Horticultural Studies 2000

survived. Tree size and productivity was significantly affected

by rootstocks (Tables 1 and 2) during the first seven growing

seasons and the first four harvest years. Trees on ‘Montclar’,

‘BY520-8’, ‘BY520-9’ (also known as ‘Guardian’) were the

tallest trees (>3.3 m) while trees on ‘Ishtara’ were significantly

smaller than others. Less variability occurred for tree width (due

to pruning to allow tractor movement) although ‘Tennessee

Natural’, ‘Montclar’ and ‘BY520-9’ all exceeded 5.0 m width.

Tree height and width were well correlated (r2 = 0.83). TCSA is

an approximation of total vegetative growth of the tree and was

well correlated to tree height (r2 = 0.81), width (r2 = 0.63) and

estimated canopy volume (inverted cone - r2 = 0.75). Tree TCSA

varied more than 327% from the smallest tree (‘Ishtara’) to the

largest tree (‘BY-520-9’). For most growth variables, the trees

on ‘Lovell’ and ‘Bailey’ were in the upper quartile of the

rootstocks tested. When a relative growth rate of TCSA increase

is calculated (increase in TCSA during 2000/Total TCSA; Table

1), trees with high relative growth rates (20-25%), or those still

rapidly growing were ‘Lovell’, ‘Nemaguard’, and ‘Tennessee

Natural’, while those growing slower (less than 16.5%) and in-

dicating they were approaching their maximum size were

‘Rubira’, ‘Stark Redleaf’, ‘Higama’, and ‘Ta Tao 5’. Trees on

‘Lovell’ and ‘Bailey’ were approximately 25-30% shorter and

narrower and had approximately 50% smaller TCSA than trees

of the same age in the previous study, presumably due to herbi-

cide and drought effects.

In spring 2000 there were no significant differences in

bloom time or first harvest date (Table 1). Previous reports in-

dicated that trees on ‘TaTao 5’ may bloom as much as 10 days

later than other rootstock cultivars due to the presence of a group

of latent viruses. In this study, trees on ‘TaTao 5’ bloomed on

average 3 days later than the average for all rootstocks. Root-

stock did not affect fruit size. This is likely partially due to the

balanced fruit thinning that was done after bloom. Rootstock

significantly affected yield efficiency both for 2000 and cumu-

lative yields. Trees on ‘TaTao 5’, ‘Rubira’, ‘Nemaguard’ and

‘Stark Redleaf’ all tended to be the most efficient trees, while

trees on ‘Higama’ and ‘Myran’ tended to produce less fruit rela-

tive to vegetative growth.

Yield varied significantly among rootstocks during the first

four seasons (Table 2). Cumulative yield in the first four sea-

sons varied 300% from trees on ‘Ishtara’, which had the lowest

yields to trees on ‘Montclar’ which had the highest yields. Cu-

mulative yield was closely correlated to tree size variables of

tree height, width, canopy volume, and TCSA (r2 = 0.76, 0.85,

0.79, and 0.56, respectively). As with tree size, yields in the

third and fourth years and cumulative yield after four seasons

in this trial were lower (40-50%) than in previous trials of the

same cultivar on comparable rootstocks. However, fruit size

was comparable.

42

AAES Research Series 483

Tab

le 1

. T

he e

ffect

of

roo

tsto

ck o

n p

each

tre

e g

row

th a

nd

fru

itin

g in

th

e N

C-1

40 1

994 P

each

Ro

ots

tock T

rial,

z F

ruit

Su

bsta

tio

n, C

lark

sville

, A

rk. 2000.

Inc. in

Avera

ge

Cum

. yie

ld

Tre

eT

ree

TC

SA

during

Date

of

Date

of

fruit

effic

iency

heig

ht

wid

thT

CS

A2000

full

firs

tw

eig

ht

Yie

ld e

ffic

iency

‘97-‘00

Ro

ots

tock

(m)

(m)

(cm

2)

(cm

2)

blo

om

harv

est

(g)

(kg/T

CS

A)

(kg/T

CS

A)

Lovell

3.0

3 b

c4.7

6 a

c74.4

cd

16.8

21-M

ar

30-J

un

149

0.4

53 a

c1.2

2 c

f

Baile

y2.9

2 c

d4.5

3 b

c78.4

cd

12.9

20-M

ar

29-J

un

172

0.3

34 r

de

1.3

4 a

d

TN

Natu

ral

3.1

6 b

c5.0

3 a

b86.5

bd

17.6

20-M

ar

01-J

ul

151

0.3

96 a

e1.2

7 b

e

Nem

aguard

2.9

6 c

4.7

5 a

c83.7

bd

21.4

20-M

ar

30-J

un

151

0.4

66 a

b1.4

0 a

c

Sta

rk R

edle

af

2.9

9 b

c4.7

4 a

c81.6

cd

12.6

21-M

ar

30-J

un

159

0.4

86 a

1.4

4 a

b

GF

305

3.0

3 b

c4.6

7 a

c95.8

bc

18

21-M

ar

30-J

un

146

0.3

44 c

e1.1

1 e

g

Hig

am

a3.0

3 b

c4.4

0 c

82.0

cd

13.2

20-M

ar

30-J

un

151

0.3

88 b

e1.1

8 d

f

Montc

lar

3.5

0 a

5.1

9 a

104.0

ab

19.1

19-M

ar

30-J

un

152

0.3

96 a

b1.1

7 d

g

Rubira

2.9

5 c

4.7

1 a

c69.7

de

10.5

21-M

ar

01-J

ul

164

0.4

67 a

d1.5

4 a

Ishta

ra2.1

4 e

3.2

8 d

39.9

f7.5

21-M

ar

29-J

un

137

0.4

20 b

d1.0

2 f-h

Myra

n3.1

9 b

c4.8

0 a

c105.5

ab

17.9

22-M

ar

30-J

un

150

0.3

19 e

0.8

8 h

S.2

729

3.1

6 b

c4.5

2 b

c87.7

bd

15.9

22-M

ar

01-J

ul

144

0.4

26 a

d1.1

6 d

g

BY

520-8

3.2

5 a

-c4.6

6 b

c90.0

bd

15.2

20-M

ar

30-J

un

141

0.3

75 b

e1.1

9 c

-f

BY

-520-9

3.3

3 a

b5.0

0 a

b121.9

a22.1

20-M

ar

30-J

un

140

0.3

01 e

0.9

5 g

h

Ta

Tao 5

2.4

9 d

e4.1

7 c

45.8

ef

7.4

23-M

ar

01-J

ul

149

0.5

13 a

1.5

0 a

b

ns

y

z M

ean s

epara

tion w

ithin

colu

mns by D

uncan’s

multip

le r

ange test, P

<0.0

5, p

erf

orm

ed w

ith S

AS

PR

OC

GLM

.

y ns n

o s

ignific

ant

diffe

rences.

43

Horticultural Studies 2000

Tab

le 2

. T

he e

ffect

of

roo

tsto

ck o

n p

each

tre

e y

ield

in

th

e N

C-1

40 1

994 P

each

Ro

ots

tock T

rial,

Fru

it R

es

ea

rch

Su

bs

tati

on

, C

lark

sv

ille

, A

R.

Tre

e Y

ield

(kg/t

ree)z

Cu

mu

lative

Yie

ld

Roots

tock

1997

1998

1999

2000

1997-2

000

Lovell

13.3

1 c

15.8

3 c

d28.0

3 a

b3

4.2

a-d

91

.4 b

-d

Baile

y18.7

0 a

-c20.1

0 a

-d30.2

3 a

b2

6.0

c-e

99

.8 a

-c

TN

Natu

ral

20.8

0 a

b19.7

2 a

-d35.5

4 a

34

.5 a

-d1

10

.2 a

-c

Ne

ma

gu

ard

22

.04

a2

1.2

1 a

-c3

3.9

7 a

b3

7.7

ab

11

4.9

ab

Sta

rk R

edle

af

18.1

9 a

-c21.6

7 a

b34.7

7 a

37

.6 a

b1

12

.3 a

-c

GF

305

17.9

0 a

-c21.2

9 a

-c31.7

7 a

b3

1.7

a-d

10

3.8

a-c

Hig

am

a18.6

9 a

-c14.7

9 a

-d28.2

9 a

b2

8.1

b-d

89

.8 c

d

Montc

lar

23.8

5 a

19.5

9 a

-d36.1

2 a

40

.6 a

12

0.2

a

Rubira

20.0

4 a

-c22.7

4 a

30.3

7 a

b3

2.7

a-d

10

5.9

a-c

Ishta

ra4.8

5 d

6.3

8 e

11.8

6 d

16.5

e39.6

e

Myra

n14.6

3 b

c16.2

9 b

-d29.0

8 a

b3

3.7

a-d

93

.7 b

-d

S.2

729

18.3

6 a

-c20.3

3 a

-d25.3

4 b

c37.2

ab

101.1

a-c

BY

520-8

19.2

8 a

-c18.6

0 a

-d34.7

4 a

34.3

a-d

106.9

a-c

BY

-520-9

21.7

8 a

17.2

6 a

-d33.8

3 a

b35.9

a-c

108.1

a-c

Ta T

ao 5

13.7

4 b

c15.2

7 c

d15.9

1 c

d2

2.9

de

67

.3 d

e

z M

eans s

epara

tion w

ithin

years

by least square

means a

t th

e .05 o

r gre

ate

r le

vel usin

g P

roc G

LM

and the L

SM

EA

NS

pro

cedure

.

44

AAES Research Series 483

RED RASPBERRY PRIMOCANE GROWTH

AND DEVELOPMENT IN TWO

HIGH-TEMPERATURE ENVIRONMENTS

IN ARKANSAS

Eric T. Stafne, John R. Clark, and Curt R. Rom1

IMPACT STATEMENT

Red raspberries are not well adapted in Arkansas, appar-

ently due to the lack of adaptation to high summer tempera-

tures. Identifying heat-tolerant red raspberries, along with the

effects of high temperatures, is needed to assist in the genetic

improvement of red raspberry. Six red raspberry cultivars were

grown at two locations in Arkansas, northwest (Fayetteville)

and southwest (Hope) to evaluate plant growth differences across

two distinct hardiness zones. Differences occurred among cul-

tivars and locations for plant maturity, leaf area, and leaf fresh

and dry weight. Only ‘Dormanred’ achieved adequate survival

and growth in the very high temperatures of the Hope location,

whereas other cultivars (Reveille and Southland) with some

southern U.S. adapted germplasm showed poor adaptation to

the environments in this study. The findings reflect the impact

of high heat on non-adapted germplasm, and provide data on

adaptation levels needed for parental consideration in breeding

for southern conditions.

BACKGROUND

Ecologically, raspberries grow in a wide range of climates

from the Arctic to the tropics. However, the horticulturally im-

portant species are adapted to cool, temperate climes (Dale,

1986; Daubeny, 1997). Apparent heat-tolerant exceptions for

raspberry have been reported, such as ‘Dormanred’ and

‘Southland’ (Hull, 1969; Overcash, 1972).

Several of the cultivars included in this study are either

proven to be southern adapted (‘Dormanred’) (Moore, 1997) or

have been recommended for the southern states (‘Reveille’,

‘Southland’) (Swartz et al., 1992). Final biomass measurement

comparisons between two high summer heat locations may give

an indication of appropriate parental material to be used in a

breeding program for heat-adapted red raspberries.

The objectives of this study were to discover if any of the

cultivars tolerated supraoptimal temperature conditions and to

observe how location affects raspberry growth and development.

RESEARCH DESCRIPTION

Red raspberry cultivars were obtained as dormant plants

from two local nurseries: Pense Nurseries and Simmons Berry

Farm, both in Mountainburg, Ark. The cultivars were ‘Autumn

Bliss’, ‘Dormanred’, ‘Heritage’, ‘Nova’, ‘Reveille’, and

‘Southland’.

Plants were potted in 3 gal pots with a Universal Mix me-

dia (Strong-Lite Hort. Prod., Pine Bluff, Ark.) and controlled

release fertilizer (Osmocote 18N-2.6P-9.9K, 17.5 oz per pot)

on 17 April 1998 for Fayetteville and 19 April 1998 for Hope

and placed in ambient field conditions. Temperatures during

the hottest month (July) averaged 93° F and 100° F for

Fayetteville and Hope, respectively. Initial whole plant fresh

weights were taken before the plants were potted. Pots were

drip irrigated at the rate of 1 gal per hour for 1 h per day in the

morning from 0800 to 0900 HR. ‘Nova’ did not produce any

canes from the rooted handles at the Hope location and more

plant material was not available.

Destructive biomass measurements were made at the end

of the growing season in September, 1998. These measurements

included leaf area, and fresh and dry weights of leaves, canes,

and roots. Roots were removed from the pot and washed thor-

oughly to remove soil. Plant parts were dried at 120° F for 10

days and dry weight recorded. Due to a fire in the plant dryer,

cane dry weight measurements were lost. Some leaves were

lost during the season due to natural senescence and death and

were not harvested. Only leaves remaining on canes, or in the

pots were harvested for the final weights. Cane mortality was

also observed during the season. Dead canes were harvested

for dry weight determinations.

FINDINGS

‘Heritage’, ‘Reveille’, and ‘Southland’ all had plant mor-

tality at the Hope location, whereas no plant loss after initial

emergence was observed at Fayetteville (data not shown). Tem-

perature data collected at both locations indicated that daytime

maximum temperatures at Fayetteville were less than those at

Hope for each month (data not shown). This more moderate

environment probably contributed to higher plant survival when

compared to Hope. Minimum temperatures were very similar

at both locations. The irrigation provided was adequate for

plant growth and development as no water stress was observed,

thus temperature was likely the determining factor in observed

differences.

At the Hope location, ‘Dormanred’ had the highest leaf area

(data not shown). At Fayetteville, ‘Heritage’ and ‘Dormanred’

produced the most leaf area. ‘Reveille’ was the poorest per-1 All authors are associated with the Department of Horticulture, Fayetteville.

45

Horticultural Studies 2000

former at both locations. ‘Dormanred’ was the only cultivar to

have more recoverable leaves at Hope than Fayetteville.

‘Dormanred’ was significantly different from all other cultivars

at both locations. ‘Reveille’ and ‘Southland’ also had far fewer

leaves at Hope when compared to Fayetteville (data not shown).

Initial fresh weight varied among cultivars, but not loca-

tions (Table 1). ‘Nova’ and ‘Reveille’ had the highest initial

fresh weight. All raspberry plants were dormant root handles.

All other cultivars, aside from ‘Dormanred’, did not differ for

total fresh weight at the end of the season averaged for the two

locations. Location also significantly affected total fresh weight.

Overall, all cultivars at Fayetteville produced more total fresh

weight than did those at the Hope location. This is likely related

to the difference in temperature.

At both locations, ‘Dormanred’ had the greatest leaf fresh

weight (Table 1). ‘Heritage’ was also high in Fayetteville. ‘Rev-

eille’ had the lowest leaf fresh weight, especially at the Hope

location. In contrast, ‘Heritage’ had among the highest fresh

weights at Fayetteville, but was lower at Hope. ‘Dormanred’

had the least reduction among locations with only a 16% re-

duction at Hope. These same results were also seen for the leaf

dry weight measurements (data not shown).

‘Heritage’ and ‘Dormanred’ had the most cane fresh weight

per plant for Fayetteville (Table 1), followed by ‘Autumn Bliss’.

‘Reveille’ was yet again a poor producer of plant material, hav-

ing the lowest cane fresh weight per plant at Hope. ‘Dormanred’,

and ‘Southland’ exhibited no differences between locations,

whereas ‘Heritage’ and ‘Reveille’ had lower values at Hope.

Cane dry weight material was lost in a plant dryer fire and

deemed unrecoverable. Therefore, no data can be presented for

that measurement.

For root fresh weight the cultivars were generally similar

(Table 1). Fayetteville had a mean of 289 g per plant and Hope

182 g per plant, a significant difference of 37% between loca-

tions. The difference was reduced to 33% for dry weight,

Fayetteville at 72 g and Hope at 48 g, but still significant.

The longer duration of high nighttime temperatures in Hope

may account for some of the differences seen in growth. Night-

time conditions in Arkansas are generally warm and humid. This

combination of conditions can lead to increased dark respira-

tion and eventual depletion of assimilate reserves of the culti-

vars. The data from this study indicated that only ‘Dormanred’

achieved adequate survival and growth in the very high tem-

peratures of the Hope location, whereas other cultivars (Rev-

eille and Southland) with some southern U.S.-adapted

germplasm showed poor adaptation to the environments of this

study. In general, all raspberry cultivars performed better at

Fayetteville than Hope. The findings reflect the impact of high

heat on non-adapted germplasm and reveal information on ad-

aptation levels needed for parental consideration in breeding

for southern conditions.

LITERATURE CITED

Dale, A. 1986. Some effects of the environment on red rasp-

berry cultivars. Acta Hort. 183:155-161.

Daubeny, H.A. 1997. Raspberry breeding in Canada: 1920 to

1995. Fruit Var. J. 51:228-233.

Hull, J.W. 1969. Southland red raspberry - A new fruit crop for

the South. Fruit Var. Hort. Dig. 23:48.

Moore, J.N. 1997. Blackberries and raspberries in the southern

United States: Yesterday, today, and tomorrow. Fruit Var. J.

51:148-157.

Overcash, J.P. 1972. Dormanred raspberry: A new variety for

Mississippi. Miss. Agr. & For. Expt. Sta. Bul. 793.

Swartz, H.J., S.K. Naess, J. Fiola, H. Stiles, B. Smith, M. Pritts,

J.C. Sanford, and K. Maloney. 1992. Raspberry genotypes

for the East Coast. Fruit Var. J. 46:212-216.

Table 1. Biomass measurements for six red raspberry cultivars at two Arkansas locations.

Initial fresh Total plant Root Leaf CaneCultivar weight (g)z fresh weight (g)z fresh weight (g)z fresh weight (g) fresh weight (g)

Fay.x Hope Fay.x Hope

Autumn Bliss 21.7 by 326.5 by 201.7 aby 64.4 bcw 42.1 bw 90.7 abw 53.8 bcw

Dormanred 16.5 b 508.8 a 271.3 a 129.2 a 108.8 a 119.5 a 117.6 a

Heritage 9.9 b 358.3 b 201.3 ab 120.5 a 35.2 bc 121.2 a 36.6 cd

Nova 55.9 b 322.0 b 209.2 ab 59.3 bc 65.4 bc

Reveille 36.1 a 256.7 b 185.5 ab 49.6 c 8.6 c 67.5 bc 15.9 d

Southland 11.2 b 279.2 b 179.2 b 77.2 b 27.4 bc 50.3 c 45.9 b-d

z Data are average of two locations - except for ‘Nova’ - because ‘Nova’ died at Hope.

x Fayetteville location.

y Means among cultivars followed by the same letter are not significantly different as determined by t test, P<0.05.

w Means among cultivars within location followed by the same letter are not significantly different as determined by t test, P<0.05,

significant differences among locations within cultivar are represented by bold italic text font. Means without bold italic are not significantly

different, P<0.05.

VEGETABLES

48

AAES Research Series 483

TOMATO CULTIVAR TRIAL RESULTS, 2000

Paul E. Cooper1

IMPACT STATEMENT

Twenty-one tomato cultivars and advanced breeding lines

were entered in a study to compare yield and quality factors.

The plants were severely infected by tomato spotted wilt virus

(TSWV) as the season progressed. As a result of this, it was

possible to screen the germplasm for resistance or tolerance to

TSWV. Cultivars rated as TSWV resistant performed well. One

cultivar rated as TSWV susceptible had yield comparable to

the resistant cultivars.

BACKGROUND

Cultivar selection is very important to the fresh market to-

mato industry in southeast Arkansas. The industry relies on the

use of well adapted cultivars that produce high yields of supe-

rior quality fruit. New cultivars are developed and released an-

nually by universities and private seed companies. In 1992,

‘Mountain Spring’ was released by Randy Gardner of North

Carolina State University and quickly became the industry stan-

dard (Gardner, 1992). The primary purpose of this study was to

evaluate new tomato cultivars for their adaptability and poten-

tial use in southeast Arkansas. A secondary purpose of this study

was to evaluate several cultivars/lines that were touted to be

resistant to TSWV, and to compare fruit yield and fruit quality

characteristics to the standard, ‘Mountain Spring’, which is sus-

ceptible to TSWV.

RESEARCH DESCRIPTION

This study was conducted on the Roger Pace commercial

tomato farm in Drew County. Similar yield trials have been

conducted at this location from 1995 through 1999. Twenty-

one genotypes were compared in the test, including the stan-

dard ‘Mountain Spring’ and five genotypes reputed to be resis-

tant to TSWV (Table 1). Tomato seeds were planted on 28 Feb.

2000, plants were transplanted from seedling flats on 15 March,

and transplants were set in the field on 11 April.

Black plastic mulch and drip irrigation were used and the

beds were fumigated with methyl bromide/chloropicrin (67:33)

at the time of laying the plastic. Insects, diseases, and weeds

were controlled using recommended practices. Plants were

staked, tied, and pruned in a manner consistent with the area.

Fruits were harvested from 20 June through 7 July and graded

into the following categories: 1) extra large #1 (XL#1), 2) large

#1 (L#1), 3) #2, and 4) #3/unclassified. Marketable fruit com-

posed the first three grades. The experimental design was a ran-

domized complete block containing four replications and plot

size was four tomato plants/plot. Data were also collected on

the progress of the infection rate of TSWV. Fruit was not

harvested from plants showing foliar and/or fruit symptoms

of TSWV.

FINDINGS

Total marketable yield varied greatly by genotype. Yields

for the resistant genotypes ranged from 29.1 lb per plot (C4067)

to 18.0 lb per plot (1405037) (Table 1). Yields of the suscep-

tible genotypes (plants that did not develop TSWV) were re-

duced by 50% and more from C4067. The standards ‘Mountain

Spring’ and ‘Mountain Fresh’ were reduced in yield approxi-

mately 75% from C4067. This was due to infection from TSWV.

All plots of ‘Sun Chief’ and ‘Sunbrite’ were completely de-

stroyed by TSWV. It is not clear why the cultivar BHN-446 (a

susceptible genotype) yielded as well as it did in relation to the

resistant/tolerant genotypes.

Average fruit weight ranged from 12.7 oz (‘Mountain

Spring’) to 7.4 oz (C4067). The very large fruit size for ‘Moun-

tain Spring’ is consistent with previous studies. BHN-444 was

approximately 2.5 oz less in weight than ‘Mountain Spring’.

However, it did compare very favorably with ‘Florida 47’ in

average weight, as it did in previous studies from Florida (S.M.

Olson and J.M. Snell, personal communication). All of the re-

sistant/tolerant genotypes were smaller in size than ‘Mountain

Spring’.

Yield per plant of most genotypes ranged from about 6 to 9

lb. Yields of the resistant/tolerant genotypes were generally

similar to the yield of ‘Mountain Spring’ and ‘Mountain Fresh’

plants that had no TSWV symptoms.

The devastation of the tomato plants by TSWV prevented

the collection of data from several entries. At the beginning of

the harvest, 52.1% of all plants in the study were already in-

fected with TSWV, including 68.4% of the susceptible geno-

type plants. By the end of the harvest on 7 July, 66% of all

plants were infected, and 83% of the susceptible genotype plants

were infected.

Even though the five “resistant” genotypes performed very

well under extreme pressure from TSWV, they may not be to-

tally resistant or immune to this disease. They do appear to be

highly tolerant of TSWV, however. Disease lesions due to

TSWV were found on a few fruits of BHN-444, C4067, and

1453688. However, foliage symptoms were not noted on any

of the five “resistant” genotypes.1 Southeast Research and Extension Center, Monticello

49

Horticultural Studies 2000

LITERATURE CITED

Gardner, R.G. 1992. ‘Mountain Spring’ tomato; NC 8276 and

NC 84173 tomato breeding lines. HortScience 27:1233-1234.

Table 1. Yields of tomato genotypes by total marketable weight, average fruit weight and yield /plant, 2000.

Genotype Total mkt. yield Average/fruit Yield/plant

(lb/plot) (oz) (lb)

C4067* 29.1az 7.36 j 7.7 b-f

BHN-444* 26.5 ab 9.98 c-f 9.0 ab

1447138* 26.5 ab 9.21 d-h 6.6 c-g

BHN-446 25.7 ab 8.06 h-j 8.6 a-d

1453688* 21.9 ab 9.58 d-g 6.4 d-g

1405037* 18.0 bc 10.38 c-e 4.5 g

BHN-316 11.3 cd 8.74 f-i 6.5 d-g

BHN-466 9.0 c-e 7.80 ij 6.9 b-f

NC 96348 7.6 de 10.01 c-f 5.8 e-g

Mountain Spring 7.3 de 12.67 a 7.4 b-f

Mountain Fresh 7.3 de 11.82 ab 7.7 b-f

NC 98100 6.3 de 11.23 bc 8.6 a-d

Florida 91 5.1 de 10.62 b-d 6.9 b-f

NC 96365 4.9 de 8.29 g-j 6.5 d-g

Sun Guard 4.4 de 9.08 e-i 8.8 a-c

Sunsation 4.0 de 9.88 c-f 8.0 b-e

BHN-442 3.2 de 9.63 d-g 6.4 d-g

BHN-306 2.7 de 7.39 j 10.6 a

Florida 47 1.4 de 9.91 c-f 5.6 fg

Sun Chief 0.0 e —— ——

Sunbrite 0.0 e —— ——-

z Means within a column followed by a different letter are significantly different as determined by Duncan’s multiple range test (P<0.05).

* TSWV resistant/tolerant genotypes.

TURFGRASSES AND ORNAMENTALS

52

AAES Research Series 483

EVALUATION OF FUNGICIDES FOR CONTROL

OF BROWN PATCH IN TALL FESCUE LAWNS

Gene A. Milus1, Michael D. Richardson2, and Chris T. Weight1

IMPACT STATEMENT

Tall fescue is one of the most popular lawn grasses in tran-

sition zone environments, where warm- and cool-seasons grasses

can be grown, due to its high quality and good tolerance of

environmental stress. However, this grass is highly susceptible

to a disease called brown patch, caused by Rhizoctonia solani.

A fungicide test was conducted to determine what measures

can be used to control this disease in tall fescue lawns. A single

application of Heritage fungicide either before or after symp-

toms developed provided excellent full-season control of this

disease. These treatments may be an effective means of sup-

pressing this disease in high-maintenance tall fescue lawns.

BACKGROUND

Tall fescue remains one of the most popular lawn grasses

in the transition zone of the United States due to its year-round

turf quality, heat tolerance, and drought tolerance. However,

one of the major weaknesses of the species is widespread sus-

ceptibility to brown patch. Turfgrass breeders have focused most

of their efforts on dark foliage color, fine texture and high den-

sity. However, brown patch resistance has been elusive, as those

cultivars with dense canopies provide a more favorable envi-

ronment for disease to occur.

A number of different fungicides are available for the con-

trol of brown patch. However, most homeowners do not use

fungicides due to a lack of knowledge, poor formulations, and

inadequate equipment. With the increased presence of pesti-

cide application companies in the homeowner market, the po-

tential to apply fungicides effectively for the control of brown

patch has increased. To this end, a fungicide test to control brown

patch in tall fescue lawns was needed to determine the best prod-

ucts and timing of application for control of this disease.

RESEARCH DESCRIPTION

A fungicide experiment was conducted on the turfgrass plots

at the Arkansas Agricultural Research and Extension Center,

Fayetteville. The plots were located on irrigated ‘Millennium’

tall fescue that was growing in full sun and was approximately

2 years old (planted fall 1998). There were 12 fungicide treat-

ments in the trial. The experimental design was a randomized

complete block with four replications. Each plot was 4 x 5 ft

and a spray shield was used to confine treatments to the plot.

Liquid formulations were applied in 4 gal per 1000 ft2 using a

hand-held CO2 sprayer. Granular formulations were applied

using a shaker can with holes in the top. The plot area annually

received 4 lb of actual nitrogen (N), with 1.0 lb N/1000 ft2 ap-

plied in March and September and 2.0 lb N/1000 ft2 applied in

November. To encourage the development of brown patch in

the test area, an additional 0.5 lb N/1000 ft2 was applied on 1

and 15 June and on 1 July, and plots were irrigated lightly (0.1

in.) at 12:30 pm each day between 15 June and 15 July. Treat-

ments were applied either before symptoms appeared (BS) or

after symptoms appeared (AS) (Table 1). Heritage treatments

were applied once, and all other treatments were applied three

times at 14-day intervals. Brown patch ratings were based on

the percentage of the plot area diseased. Turf quality ratings

were based on turf density and color.

FINDINGS

Brown patch symptoms were first noticed on 12 July and

increased slowly, but the control plots were approximately 60%

infected by brown patch by 31 Aug. (Table 1). Treatments ap-

plied after symptoms developed generally were more effective

than treatments applied before symptoms, but Immunox treat-

ments were similar with both timings. A single application of

Heritage provided the best overall control of brown patch in

this test, with less than 15% infection in both the before- and

after-symptoms treatments (Table 1). Daconil and Thiophinate

on 14-day intervals failed to effectively control the disease and

were not significantly different from controls at either measure-

ment date. Differences in turf quality were strongly associated

with brown patch severity, but all plots suffered some heat stress.

In summary, a single application of Heritage on 1 June pro-

vided good control of brown patch through mid August and

may be an effective means of suppressing this disease in tall

fescue lawns. In addition, a single application of Heritage after

symptoms occurred was also an effective treatment, giving the

homeowner an option that is dependent on the presence of the

disease.

1 Department of Plant Pathology

2 Department of Horticulture

53

Horticultural Studies 2000

Table 1. Incidence of brown patch and turf quality as affected by different fungicide treatments.

Treatment, rate of product / 1000 ft2 % Brown patchy Turf qualityx and timingz

7 Aug. 31 Aug. 31 Aug.

Heritage 50 WDG, 0.4 oz, BS 0.5 13.5 6.3

Heritage 50 WDG, 0.4 oz, AS 0.0 6.5 7.3

Immunox 1.55 SC, 14 fl oz, BS 3.8 28.8 6.0

Immunox 1.55 SC, 14 fl oz, AS 2.5 30.5 5.8

Bayleton 1 G, 24 oz, BS 12.5 55.8 4.3

Bayleton 1 G, 24 oz, AS 9.3 25.5 5.5

Daconil 29.6 FL, 3.7 fl oz, BS 18.8 55.0 4.8

Daconil 29.6 FL, 3.7 fl oz, AS 5.0 46.3 5.8

Scotts Thiophanate M. 2.3 G, 21.9 oz, BS 25.0 65.8 4.3

Scotts Thiophanate M. 2.3 G, 21.9 oz, AS 17.5 36.3 5.8

Nontreated #1 16.3 60.8 4.3

Nontreated #2 12.5 54.5 4.5

LSD (P=0.05) 12.5 26.2 1.2

y Percentage of plot area with brown patch symptoms.

x 0 = all dead, 9 = excellent turf color and density.

z BS = before symptoms (1, 15, and 29 June), AS = after symptoms (13 and 27 July and 10 Aug.); Heritage treatments were applied once on 1

June or 13 July for the BS and AS treatments, respectively, and others were applied on the three dates.

54

AAES Research Series 483

FUNGICIDE EFFECTIVENESS IN

CONTROLLING FOLIAR DISEASES OF THREE

EUONYMUS FORTUNEI CULTIVARS

James T. Cole1, Janet C. Cole2, and Kenneth E. Conway2

IMPACT STATEMENT

Damage to Euonymus fortunei from anthracnose caused

by Phlyctema vagabunda can severely impact crop salability.

This study investigated six fungicides with and without the spray

adjuvant Hyper-Active on E. fortunei cultivars Emerald Gai-

ety, Emerald ‘n Gold, and Emerald Surprise. The experiment

was conducted at Fayetteville, Ark., and Stillwater, Okla. Re-

sults indicated less disease damage on the cultivar Emerald

Surprise and the best disease control with trifloxystrobin and

mancozeb. The spray adjuvant Hyper-Active did not provide

consistent improvement in controlling disease damage when

used with any of the fungicides.

BACKGROUND

Production nurseries have difficulty finding effective dis-

ease control methods for foliar disease in E. fortunei. Maneb,

mancozeb, and chlorothalonil were reported to completely pro-

tect E. fortunei from anthracnose (Mahoney and Tattar, 1980).

Koelsch et al. (1995) found shoot dry weights were significantly

higher for Vinca minor plants exposed to Colletotrichum

gloeosporioides and treated with thiophanate methyl/mancozeb

at the end of two growing seasons compared to untreated controls.

It was previously thought that damage on E. fortunei in

Oklahoma and Arkansas, as elsewhere in the country, was caused

by C. gloeosporioides (Chase, 1983). However, researchers at

Oklahoma State University recently determined the fungal

pathogen P. vagabunda to be the cause of anthracnose damage

on E. fortunei produced in this area. The purpose of this study

was to evaluate the effectiveness of newer fungicides in limit-

ing anthracnose damage caused by P. vagabunda.

RESEARCH DESCRIPTION

This study was conducted in Fayetteville, Ark., and

Stillwater, Okla. to investigate the efficacy of six fungicides,

chlorothalonil, azoxystrobin, myclobutanil, trifloxystrobin, cu-

pric hydroxide, and mancozeb, with and without the spray ad-

juvant Hyper-Active in controlling anthracnose damage on the

three Euonymus fortunei cultivars Emerald Gaiety, Emerald ‘n

Gold, and Emerald Surprise. Plants were grown under shade

cloth to duplicate typical production conditions. Percent dam-

age ratings on a scale of 0 to 100 were taken on the plants at 4-

week intervals throughout the study. The experimental design

was a randomized complete block. Arcsine transformation was

performed on all data prior to conducting an analysis of vari-

ance using PROC GLM of SAS, and means separated by least

significant difference (LSD).

FINDINGS

Damage was minimal for all plants in Fayetteville through-

out the experiment. The only significant difference was among

cultivars on the final rating date, 26 Sept. 2000, with the high-

est percent of damage occurring on ‘Emerald ‘n Gold’ (Table 1).

In Stillwater, ‘Emerald Surprise’ had the lowest damage

percentage rating regardless of treatment for the first two rating

dates, but was not significantly different from ‘Emerald ‘n Gold’

(Table 1). A cultivar by surfactant interaction was seen on 3

July 2000 ratings in Stillwater. ‘Emerald Gaiety’ treated with-

out Hyper-Active, and regardless of fungicide, had the greatest

damage (data not shown). However, the difference in damage

was small, 4.0 with the surfactant, and 5.6 without. At the fourth

rating date (31 July), ‘Emerald Surprise’ was the least-damaged

cultivar regardless of treatment and the best control was attained

with chlorothalonil and mancozeb treatments in Stillwater (Table

2). By the fifth rating date in Stillwater, a cultivar by fungicide

interaction showed ‘Emerald Surprise’ plants treated with

chlorothalonil and mancozeb had the lowest damage ratings,

though they were not significantly lower than ‘Emerald Sur-

prise’ plants treated with trifloxystrobin (data not shown). For

the same rating date in Stillwater, the fungicide by adjuvant

interaction showed that the least damaged plants were either

those treated with chlorothalonil without Hyper-Active or

mancozeb plus Hyper-Active (data not shown). Plants treated

with cupric hydroxide plus surfactant, and myclobutanil, or

azoxystrobin with or without surfactant, were not significantly

different than the water control.

Dramatic differences in percent damage were observed be-

tween the two sites. Regardless of treatment, Fayetteville had

only slight damage on few plants while damage was severe on

all plants at Stillwater. A possible explanation for the dissimi-

larity in damage for the two sites is the temperature difference

at Fayetteville and Stillwater. This hypothesis will be tested

in 2001.

1 Department of Horticulture, Fayetteville

2 Oklahoma State University, Stillwater

55

Horticultural Studies 2000

LITERATURE CITED

Chase, A.R. 1983. Two foliar diseases of Euonymus spp. Foli-

age Digest 6(1):14.

Koelsch, M.C., J.C. Cole, and S.L. von Broembsen. 1995. Ef-

fectiveness of selected fungicides in controlling foliar dis-

eases of common periwinkle (Vinca minor L.) HortScience

30:554-557.

Mahoney, M.J. and T.A. Tattar. 1980. Identification, etiology,

and control of Euonymus fortunei anthracnose caused by

Colletotrichum gloeosporioides. Plant Disease 64:854-856.

ACKNOWLEDGMENTS

The authors thank Peggy Reed, Scott Starr, Tina Buxton,

and Jason Collins for assistance with data collection and treat-

ment applications. Also, we wish thank Greenleaf Nursery for

plant donations, technical assistance, and financial support for

this research.

Table 2. Damage ratings on 31 July 2000 from

anthracnose caused by Phlyctema vagabunda on three

cultivars of Euonymus fortunei in Stillwater, Okla., treated

with fungicides (n=84 for cultivar and n=36 for fungicide

treatment). Rating scale used was

0 to 100% plant damage.

Treatment Damage rating (%)

Cultivar main effect

Emerald Gaiety 85.1 az

Emerald ‘n Gold 89.9 a

Emerald Surprise 74.0 b

Significance (P) <0.0001

Fungicide main effect

Water 96.1 a

Trifloxystrobin 78.3 b

Chlorothalonil 65.3 c

Myclobutanil 97.9 a

Azoxystrobin 96.4 a

Cupric hydroxide 83.3 b

Mancozeb 63.8 c

Significance (P) <0.0001

z Mean separation within cultivar and fungicide treatment by LSD

(P<0.05).

Table 1. Damage rating from anthracnose caused by

Phlyctema vagabunda on Euonymus fortunei ‘Emerald

Gaiety’, ‘Emerald ‘n Gold’ and ‘Emerald Surprise’ in

Fayetteville, Ark., on 26 Sept. 2000 and in Stillwater, Okla.,

on 9 May 2000 and 6 June 2000 (n=84). Rating scale used

was 0 to 100% plant damage.

Fayetteville Stillwater

damage damage

rating (%) rating (%)

Cultivar 26 Sept. 9 May 6 June

Emerald Gaiety 0.1 bz 2.3 a 7.0 a

Emerald ‘n Gold 1.4 a 1.5 b 3.0 b

Emerald Surprise 0.1 b 0.8 b 1.7 b

Significance (P<0.05) 0.0070 0.002 <0.0001

z Mean separation by LSD (P<0.05).

56

AAES Research Series 483

PLANT GROWTH REGULATOR EFFECTS ON

IN VITRO PROPAGATION OF

ITEA VIRGINICA ‘ HENRY’S GARNET’

Jon T. Lindstrom and Matthew C. Pelto1

IMPACT STATEMENT

Shoot tip culture can be used to propagate large numbers

of plants for both experimentation and introduction to the nurs-

ery industry. A protocol for shoot tip culture of Itea virginica

‘Henry’s Garnet’, a potentially valuable plant to the Arkansas

nursery industry, has not been established. This study evalu-

ated the effects of three concentrations of the cytokinin BA (N-

[phenylmethyl]1H-purine-6-amine) combined with three con-

centrations of the auxin NAA (2-methyl-1-naphthylacetic acid)

on ‘Henry’s Garnet’ microshoot proliferation. The plant growth

regulator combination eliciting the highest proliferation level

was 4 mM (0.9 mg/L) BA with 0.1 mM (0.019 mg/L) NAA.

This medium has since been used to induce useful levels of

proliferation in Itea virginica cultivars and three additional Itea

species; I. ilicifolia, I. oldhamii, and I. chinensis. All of the Itea

genotypes propagated using shoot tip culture have been rooted.

The information generated by this research permits the rapid

propagation of valuable Itea genotypes for dissemination

throughout the Arkansas nursery industry.

BACKGROUND

Members of the genus Itea possess horticultural traits that

are highly desirable in managed landscapes. These characteris-

tics include fragrant flowers, attractive fall color, and freedom

from major pests and diseases (Farmer, 1996). However, many

cultivars of the most commonly grown Itea species, I. virginica,

have not been adequately evaluated for their usefulness in the

landscape. Part of the problem is a small supply of certain cul-

tivars. The production of sufficient numbers for evaluation of

superior genotypes necessitated the development of an effec-

tive shoot micropropagation protocol for Itea.

Shoot micropropagation, a type of plant tissue culture, in-

volves the aseptic establishment of shoot tips on a defined nu-

trient medium and the inducement of adventitious buds on these

shoots that give rise to new shoots (microshoots) in a process

termed proliferation. Microshoots can be divided and used as

explants in further proliferation cycles, or they can be rooted,

acclimated, and grown to mature plants for use in landscaping.

Achieving useful levels of proliferation requires the determina-

tion of an optimal balance between cytokinins and auxins

through experimentation. The varying degrees of microshoot

proliferation induced in Itea explants by factorial combinations

of the cytokinin BA and the auxin NAA were evaluated statisti-

cally to ascertain the best combination for Itea micropropagation.

RESEARCH DESCRIPTION

Actively growing shoot tips were harvested from a stock

plant of I. virginica ‘Henry’s Garnet’ maintained in a green-

house at the University of Arkansas Research and Extension

Center, Fayetteville. The shoot tips were disinfected in a three-

part procedure. They were first rinsed in running water for 15

minutes, then immersed in 70% ethanol (v/v) for 1 minute. The

final step was agitation for 15 minutes in a 10% v/v chlorine

bleach solution (0.6 % w/v sodium hypochlorite) with five drops

of Tween-20. After disinfection, the shoot tips were aseptically

transferred to an initial proliferation medium containing full-

strength Murashige and Skoog (1962) basal salts, the Linsmaier

and Skoog (1965) organic supplement (100 mg/L myo-inositol

and 0.4 mg/L thiamine), 30 g/L sucrose, 0.5 g/L MES (2-N-

morpholinoethanesulfonic acid), 4 mM (0.9 mg/L) BA, 0.1 mM

(0.019 mg/L) NAA, and 6.8 g/L agar adjusted to a pH of 5.7

with 1 M potassium hydroxide. Culture vessels were 125-mL

glass jars capped with Magenta-B lids (Magenta Corp., Chi-

cago, Ill.), and the interface between the lid and the jar was

sealed with a single layer of Parafilm to prevent excessive mois-

ture loss. Cultures were maintained at a temperature of 24° C(75.2° F) under bright white fluorescent lights for a 16-hour

day.

After several subculture periods (one subculture period con-

sisted of 35 days), sufficient uniform microshoots were avail-

able to initiate a 3 X 3 factorial experiment with five replicates

per treatment. A replicate consisted of a culture vessel contain-

ing a single 0.5 cm (0.2 in.) microshoot. The trial proliferation

medium had the same composition as the initial proliferation

medium except for the experimental variations in BA and NAA

concentrations, and the environmental cultural conditions were

also the same as previously mentioned. Experimental BA con-

centrations were 1 mM (0.23 mg/L), 4 mM (0.9 mg/L), and 10

mM (2.3 mg/L), and NAA concentrations were 0.01 mM (0.0019

mg/L), 0.1 mM (0.019 mg/L), and 1.0 mM (0.19 mg/L). One

additional treatment containing neither BA nor NAA served as

a control.

1 Both authors are associated with the Department of Horticulture, Fayetteville.

57

Horticultural Studies 2000

Following a 35-day subculture period, the level of prolif-

eration for each treatment was assessed by dividing the result-

ant microshoot clumps, counting the number of usable

microshoots (0.5 cm in length) per replicate, and averaging the

replicates within each treatment. The experiment was repeated

two more times. Mean microshoot data were analyzed using

the SAS system with mean separation by least significant dif-

ference (LSD). The treatment lacking plant growth regulators

did not produce new microshoots and was excluded from the

statistical analysis for this reason.

The same procedure outlined above was also used with six

additional cultivars of I. virginica: ‘Saturnalia’, ‘Sarah Eve’,

‘Long Spire’, ‘Sprinch’ (Little Henry)™, ‘Merlot’, and

‘Theodore Klein’. Three evergreen species of Itea, I. oldhamii,

I. ilicifolia and I. chinensis were also introduced into culture

using this procedure.

FINDINGS

The highest level of microshoot proliferation was for

‘Henry’s Garnet’ was induced with 4 mM BA and 0.1 mM NAA

(Fig. 1). The treatment without BA and IBA rooted in vitro dur-

ing the course of the subculture period. Average microshoot pro-

duction was significantly higher with 0.1 mM NAA than with

any other NAA treatment level across a given BA level (Fig. 1).

Each cultivar proliferated on the proliferation medium either as

well as ‘Henry’s Garnet’ or better. This medium provided satis-

factory results for propagating I. ilicifolia, I. oldhamii, and I.

chinensis. All of the Itea genotypes that have been propagated

through microshoot proliferation have also been successfully

rooted and acclimated.

LITERATURE CITED

Farmer, J. 1996. 10 Sweet Iteas. American Nurseryman

183(7):50-56.

Linsmaier, E. and F. Skoog. 1965. Organic growth factor

requirements of tobacco tissue cultures. Physiol. Plant.

18:101-127.

Murashige, T. and F. Skoog. 1962. A revised medium for rapid

growth and bio-assays with tobacco tissue cultures. Physiol.

Plant. 15:473-487.

Fig. 1. Effect of BA and NAA on Itea virginica ‘Henry’s

Garnet’. Columns with the same letter are not signifi-

cantly different by LSD (P<0.05).

58

AAES Research Series 483

HERBICIDE EVALUATIONS FOR

ESTABLISHMENT OF

NEWLY-SEEDED BERMUDAGRASS

John McCalla1, Michael D. Richardson1, John W. Boyd2, and

Douglas E. Karcher1

IMPACT STATEMENT

Weed control during the establishment of seeded

bermudagrass is a major factor in the success of the planting.

This study evaluated the effects of several postemergence her-

bicides on newly-established bermudagrass seedlings. In addi-

tion, a second technique was evaluated which used activated

charcoal to protect bermudagrass seed rows from preemergence

herbicides. All postemergence herbicides tested in this study

caused some injury on the juvenile turf, but the turf recovered

quickly from injury. The use of activated charcoal and preemer-

gence herbicides proved to be an effective technique for estab-

lishing seeded bermudagrass.

BACKGROUND

Bermudagrass is a commonly used warm-season turfgrass

in the southern United States. Until recently, seeded

bermudagrass cultivars have not matched the quality or perfor-

mance of vegetatively propagated hybrids. Over the past 20 years

the National Turfgrass Evaluation Program (NTEP) has rou-

tinely conducted cultivar trials that rate a number of vegeta-

tively and seed-propagated turfgrasses for quality and perfor-

mance. These trials are generally planted in 20 to 30 locations

across the U.S. and evaluated for 4 to 6 years. In early trials,

the quality of seeded bermudagrass cultivars was well below

those of the vegetatively-propagated standards ‘Tifway’ and

‘Midlawn’ (Morris, 1993). ‘Mirage’ seeded bermudagrass was

introduced in 1992 and showed improvement over earlier seeded

types, but the quality remained below the vegetatively-propa-

gated standards (Morris, 1997). In the 1997 bermudagrass test,

several new seeded cultivars of bermudagrass demonstrated

quality that is equal to or higher than the vegetative standards

‘Tifway’ and ‘Midlawn’ (Morris, 2000). Of the seeded geno-

types, the cultivar, Princess, and the experimental line, OKS

95-1, showed exceptional quality relative to the hybrids. These

improvements in overall turf quality of seeded cultivars could

make seeding a high-quality bermudagrass turf a realistic op-

tion.

A major problem with seeding bermudagrass is the control

of grass and broadleaf weeds during establishment. Although

many studies have evaluated weed control strategies and herbi-

cide injury in established bermudagrass, minimal work has been

done with seeded bermudagrass. Many effective postemergence

strategies are available for established bermudagrass, but ap-

plications of postemergence herbicides can lead to varying de-

grees of injury including retardation of growth, altered plant

development and ultimately plant death in seedling

bermudagrass (Millhollon, 1985). Finding appropriate

postemergence herbicides and application timings that are ef-

fective in weed control and have limited injury to bermudagrass

seedlings is important.

Preemergence herbicides can be effectively used in the es-

tablishment of vegetatively-propagated bermudagrass and in

established bermudagrass turf, but they have limited applica-

tions in seed establishment plantings. The application of a char-

coal band over a seeded furrow was developed by Lee (1973)

to protect seeds from the effects of preemergence herbicides.

Charcoal is an extremely porous, highly-absorbent product that

is a result of combustion of carbon-containing compounds

(Unruh and Brecke, 1999). Charcoal has the ability to bind and

deactivate herbicides, and has been effectively used in conjunc-

tion with preemergence herbicides to establish production fields

of cool-season grasses (Lee, 1973) and centipedegrass turf

(Johnson, 1976). However, this technique has not been at-

tempted for the establishment of a seeded bermudagrass turf.

Recent improvements in seeded bermudagrass turf quality

have stimulated increased interest in the turfgrass industry.

However, developing effective weed control strategies to aid in

the establishment of these grasses will be critical to their long-

term success.

RESEARCH DESCRIPTION

A preemergence and postemergence herbicide study was

conducted at the Arkansas Agricultural Research and Exten-

sion Center, Fayetteville. Prior to planting, both plot areas were

fumigated with methyl bromide (67%) and chloropicrin (33%)

at a rate of 392 lb/acre to ensure a weed-free site. Since the

weed control effectiveness of the herbicides tested was previ-

ously established, it was easier to rate herbicide injury without

interference from weeds. ‘Princess’ seeded bermudagrass was

chosen for both studies because of its high quality and com-

1 Department of Horticulture, Fayetteville

2 Pest Management Section, Cooperative Extension Service, Little Rock

59

Horticultural Studies 2000

mercial availability. Nitrogen was applied bi-weekly as urea

(46-0-0) at a rate of 0.5 lb N/1000 ft2.

The objective of the postemergence study was to evaluate

injury and application timings of seven postemergence herbi-

cides (Table 1) on newly-seeded bermudagrass. The plot area

was broadcast seeded on 31 May 2000 with ‘Princess’ at a rate

of 0.5 lb/1000 ft2. Herbicide applications were applied at 1, 2,

and 4 weeks after emergence (WAE) in a spray volume of 40

gal/acre. The experimental design was a completely random-

ized block design with four replications. Individual plot size

was 4 x 5 ft and a spray shield was used to eliminate herbicide

drift from plot to plot. Visual injury ratings were taken at 3, 5,

7, 15, 30, and 60 days after treatment (DAT). Data were ana-

lyzed using analysis of variance procedures and mean separa-

tions determined by Fisher’s Protected LSD (P=0.05).

The preemergence experiment evaluated activated charcoal

banding and three preemergence herbicides (Table 1) as a means

of establishing seeded bermudagrass. ‘Princess’ was planted

on 12 in. centers on 26 July 2000 using a 48 in. Gandy®

Overseeder/Dethatcher. The seeding rate was 84 seeds/ linear

foot and was applied with Greens Grade Milorganite (6-2-0) as

a carrier at a rate of 4 lb/1000 ft2. For half of each block, acti-

vated charcoal was banded (1 in.) directly over the seeded row

using a CO2 sprayer at a rate 0.5 g charcoal/ linear ft. Preemer-

gence herbicides were applied directly after planting in a vol-

ume of 40-gal/acre. The experimental design was a split plot

design with charcoal treatments assigned as main plots and her-

bicide treatments assigned as sub plots. Visual emergence rat-

ings were taken at 3, 5, and 7 days after emergence (DAE).

Percentage turfgrass cover was evaluated weekly using digital

image analysis with SigmaScan software (Richardson et al.,

2000). The effects of charcoal banding and herbicide treatments

were analyzed by analysis of variance of the split-plot model.

FINDINGS

Time after emergence for herbicide applications had no

effect on the injury caused by the various postemergence herbi-

cides (data not shown). As such, all three application timings

were averaged for this report. All postemergence herbicides

caused some degree of injury on newly seeded ‘Princess’ (Fig.

1). Diclofop, metsulfuron, and 2,4-D produced the highest lev-

els of injury. Surprisingly, monosodium methanearsenate

(MSMA) produced very little injury, which will allow turf man-

agers to effectively control grassy weeds such as crabgrass dur-

ing the establishment period. There were no statistically-sig-

nificant differences between MSMA, clopyralid, quinclorac, and

dicamba, while diclofop, metsulfuron, and 2,4-D did show sta-

tistically higher total injury over other herbicides (Fig. 1). Plots

that were injured by herbicides recovered fully and injury was

insignificant from controls at 30 DAT. At 60 DAT there was no

evidence of herbicide injury in any treatments (Fig.1). These

data suggest that several postemergence weed control strate-

gies will be available for control of both broadleaf and grassy

weeds in newly-seeded bermudagrass turf.

Activated charcoal successfully protected seeds from

preemergence herbicides (Figs. 2, 3), while those not treated

with charcoal failed to germinate (data not shown). In addi-

tion, there were no significant differences between control, char-

coal-banded treatments and control, non-charcoal banded plots

(data not shown). Control plots showed 86% germination in

charcoal treated plots (Fig. 2). Seeds in charcoal-banded plots

treated with diuron germinated equivalently to the control. Ger-

mination in charcoal-banded plots treated with prodiamine or

oxadiazon was less but acceptable at 7 DAE. In the charcoal-

banded plots, there were no significant differences in percent-

age turfgrass cover at 1 WAE between all herbicide treatments.

However, plots treated with oxadiazon produced significantly

less cover at 2, 3, and 4 weeks after planting than control plots

or diuron-treated plots (Fig. 3). These differences were not sta-

tistically significant at 6 weeks after planting. Although com-

plete cover was not reached in this trial due to a late July estab-

lishment date, it is predicted that complete cover will be pos-

sible in 6 to 8 weeks of good growing conditions.

In summary, significant injury resulted from several

postemergence herbicides, including diclofop, metsulfuron, 2,4-

D, and dicamba. However, all plots recovered fully from her-

bicide injury by 30 DAT. These data suggest that postemergence

herbicide programs can be used effectively to control weeds in

newly-seeded bermudagrass. Charcoal banding effectively pro-

tected seed rows and allowed bermudagrass to establish from

seeds in the presence of preemergence herbicides. However,

diuron-treated plots showed better results than those treated with

oxadiazon or prodiamine. These studies will be repeated during

the 2001 growing season to confirm these results.

LITERATURE CITED

Johnson, B.J. 1976. Effect of activated charcoal on herbicide

injury during establishment of centipedegrass. Agron. J.

68:802-805.

Lee, W.D. 1973. Clean grass seed crops established with acti-

vated charcoal bands and herbicides. Weed Sci. 21:537-541.

Millhollon, R.W. 1985. Progressive kill of rhizomatous

johnsongrass (Sorghum halepense) from repeated treatments

with dalaphon, MSMA, or asulam. Weed Sci. 33:216-221.

Morris, K.N. 1993. National Turfgrass Evaluation Program,

1986 National Bermudagrass Test. NTEP No. 93-1, United

States Department of Agriculture. Beltsville, Md.

Morris, K.N. 1997. National Tufgrass Evaluation Program, 1992

National Bermudagrass Test. NTEP No. 97-8, United States

Department of Agriculture. Beltsville, Md.

Morris, K.N. 2000. National Turfgrass Evaluation Program,

1997 National Bermudagrass Test. NTEP No. 00-4, United

States Department of Agriculture. Beltsville, Md.

Richardson, M.D., D.E. Karcher, B.S. Wright, and L.E. Purcell.

2000. Evaluation of turfgrass parameters using digital im-

age analysis. Agronomy Abstracts, ASA, Madison, Wis. p.

170.

Unruh, J.B., B.J. Brecke. 1999. Activated charcoal for pesti-

cide deactivation. University of Florida Pest Control Guide.,

J.B. Unruh (ed.). p. 62.

60

AAES Research Series 483

Fig. 1. Herbicide injury of newly-seeded ‘Princess’

bermudagrass as affected by broadleaf (top) and grass

(bottom) herbicides. Herbicides were applied at 1, 2, and 4

weeks after emergence and data for this graph are

averaged across all application periods. Error bars

indicate significant differences between herbicide

treatments at each evaluation periods (P<0.05).

Fig. 3. Turfgrass cover over time as affected by charcoal

banding and preemergence herbicides. * = Significantly

different from control at that evaluation date, ns= not

significantly different from control (P<0.05) .

Table 1. Herbicide treatments used in preemergence and

postemergence studies.

Herbicide Rate (lb ai/acre)

Postemergence

MSMA 1.0

metsulfuron 0.019

diclofop 1.0

clopyralid 0.5

dicamba 0.5

2, 4-D Amine 0.5

quinclorac 0.75

Preemergence

prodiamine 1.0

oxadiazon 2.0

diuron 1.0

Fig. 2. Seedling emergence of ‘Princess’ bermudagrass as

affected by charcoal banding and preemergence herbi-

cides. Different letters indicate a significant difference

between herbicide treatments (P<0.05).

61

Horticultural Studies 2000

EVALUATION OF 10 SLOW-RELEASE

FERTILIZERS ON THE GROWTH OF THREE

WOODY PLANTS AT A COMMERCIAL

CONTAINER NURSERY

James Robbins1

IMPACT STATEMENT

Ten fertilizer treatments were evaluated at a commercial

nursery in Magnolia, Ark. Results suggest that the grower has

several fertilizer options that will maintain plant quality at a

lower cost than the current nursery standard.

BACKGROUND

Slow-release fertilizers are the predominant type of prod-

uct used in the container nursery industry today. Advantages to

growers when compared to soluble granular fertilizer sources

are reduced leachate loss of nutrients and fewer applications

required (Cabrera, 1997; Fuller, 1990; Ruter, 1992; Smith and

Treaster, 1991).

The primary purpose of this research/demonstration project

was to evaluate alternative fertilizer products and rates com-

pared to the current nursery standard for a large-scale container

nursery in southwest Arkansas.

RESEARCH DESCRIPTION

The experiment was conducted on an outdoor gravel con-

tainer bed at a 200-plus acre nursery in Magnolia, Ark. (USDA

cold hardiness zone 8). Fertilizer treatments were selected as

potential alternatives to the current nursery standard, which is

Nutricote Total 18-6-8 Type 140 applied as a topdress, at an

annual rate of 5.8 lb N/yd3. This standard material was split into

two equal amounts; one-half (2.9 lb N/yd3) applied on 16 Feb.

1999 and the balance (2.9 lb N/yd3) applied on 15 July. The

other 9 treatments, including a one-half N rate (2.9 lb/N yd3/

year) Nutricote Total along with one-half N rates of eight other

products, were applied in either 1 or 2 applications according to

the manufacturer recommendation (Table 1). The initial

application was at potting (16 Feb. 1999). If required, a second

application was made 15 July, the same date as the standard

material.

Liners of three species, Rhododendron ‘Pink Ruffles’ (aza-

lea), Ilex cornuta ‘Needlepoint’ (holly), and Hypericum

calycinum (St. Johnswort), were planted into plastic pots (245

pots/yd3) using a 100% pine-bark medium. Water was supplied

as needed by an overhead irrigation system. Treatments con-

sisted of eight single-plant replications in a completely random-

ized design. Containers were initially spaced can tight, but spread

to a 1X spacing (1 times the diameter of the pot) after being

sheared on 15 July using standard nursery practices.

The experimental blocks were de-randomized on 15 July

(6 months), and two employees of the nursery were asked to

rank the three plant species at that date. Two of the head grow-

ers were asked to rank the top three fertilizer choices and bot-

tom three fertilizer choices based on the overall color and qual-

ity of the plants. A similar rating was done at the end of the

experiment. A growth index was calculated for the azalea and

holly as these species demonstrated significant visual differ-

ences in the ratings. This index was a volume measurement taken

at the beginning and end of the 12-month period, with the

difference in the two volumes calculated providing the index

volume.

FINDINGS

By the mid point in the study (6 months after potting), clear

differences were noted by the nursery employees as far as dif-

ferences in plant quality for the azalea and holly (data not

shown). For the azalea, the top three fertilizer treatments, start-

ing with the best and going down in rank, were the current nurs-

ery standard (Nutricote 18-6-8; 5.8 lb N/year), followed by

Pursell 17-5-10, and the TriPro 17-5-11. The lowest rated aza-

lea plants were associated with Scotts 18-5-9, Scotts 15-9-12,

and the lowest ranked treatment which was the Pursell 18-3-6.

For the holly, the top ranked treatment was the current nursery

standard (Nutricote 18-6-8; 5.8 lb N/year), followed by the

Pursell 16-5-11 and the 17-5-10, and then the TriPro 18-6-12,

with the lowest ranked treatment at 6 months the Pursell 18-3-

6. The nursery employees could not identify any clear quality

differences in the St. Johnswort after 6 months.

By the end of the experiment, some of the employee rat-

ings for plant quality had changed somewhat from the 6-month

observations. One clear change noted for the azaleas was that

the current nursery standard (Nutricote 18-6-8; 5.8 lb N/year)

had dropped out of the top rating group. This treatment was

unacceptable based on insufficient growth, overly dark foliage

color, and poor flower bud set. The overall rating of azaleas

indicated the best fertilizers were Nutricote 18-6-8 at the one-

half rate of 2.9 lb N/year, Pursell 17-5-10, Scotts 19-5-9, fol-

1 Cooperative Extension Service, Little Rock

62

AAES Research Series 483

lowed by Pursell 18-3-6. The worst fertilizer treatment for aza-

leas was the Scotts 15-9-12.

Although quality differences were noted by the nursery em-

ployees with the holly, they were minor. No fertilizer treatments

were identified as producing an unacceptable holly plant and

all plants were rated salable. Similar to the 6-month quality rat-

ing, the nursery employees could not identify a difference in

plant quality for the St. Johnswort at the 12-month rating.

Growth indices calculated for the holly (data not shown)

and azalea (Table 2) after 12 months generally agreed with the

nursery employee quality ratings. Azalea plants fertilized using

Nutricote 18-6-8 at 2.9 lb N/yd3 were identified as having the

best overall quality rating and the second largest growth index

(36,000 cm3). Plants identified by the staff as the lowest quality

azaleas were also on average the smallest plants (21,000 cm3).

Product costs varied from $0.036 to $0.164 per container year.

This cost does not include the labor required to apply products

once or twice per year.

Based on the visual quality rating, the growth index, and

the product cost, it was determined that this nursery had several

viable options compared to the current nursery fertilizer prac-

tice. Several products offer the grower improved plant quality

at a substantially lower cost. This demonstration project illus-

trates the value to growers of establishing small-scale product

trials to evaluate appropriate products under their growing

conditions.

LITERATURE CITED

Cabrera, R. I. 1997. Let the nutrients flow…slowly. American

Nurseryman 185(5):32-35.

Fuller, D.L. 1990. Evaluation of nutrient release rate of six slow

release fertilizers and subsequent growth of shore juniper.

Proc. Southern Nursery Assn. 35:93-97

Ruter, J.M. 1992. Leachate nutrient content and growth of two

hollies as influenced by controlled release fertilizers. J.

Environ. Hort. 10:162-166.

Smith, E.M. and S.A. Treaster. 1991. A comparison of slow-

release fertilizers for the nursery industry. In: Ornamental

Plants: A Summary of Research. The Ohio State University

p. 16-18.

63

Horticultural Studies 2000

Table 1. Fertilizer products, rates, and frequency of application. Nursery standard Nutricote Total at 5.8 lb N/yd3

is not included.

Longevity

Manufacturer/brand Analysis (months) lb N/yd3 Applications/yr lb N/yr

Nutricote Total 18-6-8 3 – 4 1.45 2 2.9

Scotts/Osmocote 19-5-9 12 –14 2.9 1 2.9

Scotts/Osmocote 18-5-9 10 –12 2.9 1 2.9

Scotts/Osmocote 15-9-12 8 – 9 2.9 1 2.9

Pursell/PolyOn 17-5-10 5 – 6 1.45 2 2.9

Pursell/PolyOn 16-5-11 8 – 9 2.9 1 2.9

Pursell/PolluOn 18-3-6 3 – 4 1.45 2 2.9

TriPro/Multicote 18-6-12 8 – 9 2.9 1 2.9

TriPro/Multicote 17-5-11 10 – 12 2.9 1 2.9

Table 2. Effect of fertilizer type on the mean growth index of azalea after 12 months (22 Feb. 2000). All materials except

the nursery standard were applied at an annual rate of 2.9 lb/N/yd3.

Fertilizer treatment Mean growth index (cm3)

Nursery standard: Nutricote 18-6-8; 5.8 lb N 23,000bz

Nutricote 18-6-8 36,000 ab

Scotts/Osmocote 19-5-9 42,000 a

Scotts/Osmocote 18-5-9 28,000 ab

Scotts/Osmocote 15-9-12 21,000 b

Pursell/PolyOn 17-5-10 31,000 ab

Pursell/PollyOn 16-5-11 27,000 ab

Pursell/PolyOn 18-3-6 22,000 b

TriPro/Multicote 18-6-12 24,000 b

TriPro/Multicote 17-5-11 29,000 ab

z Mean separation by Tukey LSD (P=0.05).

64

AAES Research Series 483

IMPACT OF ORGANIC AMENDMENTS AND

FERTILIZATION STRATEGIES

ON ESTABLISHMENT OF ZOYSIAGRASS TURF

FROM SPRIGS

Michael D. Richardson and Gene P. Bordelon1

IMPACT STATEMENT

The rapid establishment of zoysiagrass (Zoysia japonica)

from sprigs can have a significant impact on many turfgrass

sites, including sod production, golf courses, and home lawns.

A study was conducted to look at the effects of an organic amend-

ment and various rates and forms of nitrogen (N) on establish-

ment of ‘Meyer’, ‘Cavalier’, and ‘El Toro’ zoysiagrasses. The

organic amendment, GroWin®, had a significant effect on the

establishment of ‘El Toro’, but had no effect on ‘Meyer’ or

‘Cavalier’. Neither increased N rates nor foliar N applications

had any impact on rate of establishment. These studies further

support earlier findings that fertilizer inputs have little or no

effect on the establishment of zoysiagrass from sprigs.

BACKGROUND

Previous studies conducted at the University of Arkansas

have demonstrated that an organic soil amendment marketed

under the trade name GroWin® can produce a significant in-

crease in establishment rates of several turfgrass species under

various soil conditions (Richardson et al., 1999). One area where

this amendment failed to enhance establishment was during the

establishment of ‘Meyer’ zoysiagrass from cut sprigs

(Richardson, unpublished data). Several possible reasons could

exist for this lack of response. First, ‘Meyer’ zoysiagrass is an

inherently slow-growing grass, taking as long as three years to

establish a full turf from sprigs (Henry et al., 1988). In addition,

previous studies have shown little, if any, response of ‘Meyer’

to N during sprig establishment (Carroll et al., 1996; Fry and

Dernoeden, 1987; Richardson and Boyd, 2001).

Although ‘Meyer’ zoysiagrass continues to be the major

cultivar in the transition zone where both warm and cool sea-

son turfgrasses can be grown, other zoysiagrass cultivars have

emerged in the last 10 years that are gaining interest in the sod

trade. Of the many new cultivars, ‘El Toro’ and ‘Cavalier’ are

in various stages of production in Arkansas. Both are quite

distinct from each other relative to morphology and growth habit.

‘El Toro’ is the oldest of the cultivars and, once established, is

slightly more coarse in texture than ‘Meyer’. It is a very ag-

gressive cultivar that can be grown and marketed quickly. ‘Cava-

lier’ is a very fine-textured Z. matrella cultivar that should find

a niche in the high-end turf market. With respect to growth rate,

‘Cavalier’ is considered intermediate between ‘Meyer’ and ‘El

Toro’.

Based on the limited studies conducted to date on estab-

lishment of zoysiagrass from sprigs, and the continued use of

this species by the golf and landscape industries, further studies

on establishing this grass from sprigs are needed. The objective

of this study was to expand knowledge of cultural effects on

zoysiagrass sprig establishment, focusing on the potential effects

of an organic amendment (GroWin®), N rates, and foliar- vs.

root-feeding of N.

RESEARCH DESCRIPTION

A field study was established on a fumigated site at the

Arkansas Agricultural Research and Extension Center,

Fayetteville. The site is located in USDA Hardiness Zone 6 and

the soil is a Captina silt loam soil, typic hapludults, pH 6.2.

The site was fertilized with 90 lb/acre of 0N-8.8P- 16.6K and

prepared to seed-bed quality prior to planting on 5 June 2000.

The study was arranged as a randomized complete block, split-

split-plot design, with cultivar as the main plot factor, GroWin®

treatments as the first split, and post-planting fertilization meth-

ods as the second split factor. Main plots were 18 x 21 ft and

treatments included the cultivars Cavalier, El Toro, and Meyer.

GroWin® plots were 6 x 21 ft and included a control (no

GroWin®), GroWin® at 25 lb/1000 ft2 and GroWin® at 50 lb/

1000 ft2. Prior to sprigging, GroWin® was incorporated with a

rototiller to a 4-in. depth. Fertility plot size was 3 x 6 ft and

fertilizer treatments included those listed in Table 1. Granular

fertilizers were applied by hand while weekly foliar applica-

tions were applied using a CO2 sprayer with a carrier volume

equivalent to 80 gal/acre. Foliar nutrients were applied during

dry periods to assure foliar uptake.

To assure uniform planting densities, the main plots were

planted in sub-plot increments, using the GroWin® plots as the

plot size for planting. Sprigs of each cultivar were obtained from

shredding 2.3 yd2 of freshly harvested sod. This sprigging rate

(800 bushels/acre) was based on the definition that one bushel

(1.25 ft3) of sprigs represents those obtained from 1 yd2 of sod

(McCarty et. al, 1999). Sprigs were uniformly broadcast over

the sub-plot area, pressed lightly into the soil using a roller, and

watered immediately to prevent desiccation. Oxadiazon was

applied to all plots at 3.0 lb / acre immediately after planting to

suppress weeds, and water was applied as needed during the

test to provide optimum growing conditions.

1Both authors are associated with the Department of Horticulture, Fayetteville

65

Horticultural Studies 2000

Plots were rated monthly for percentage cover by two rat-

ers beginning at 60 days after planting (DAP). Cover estimates

from the two raters were combined for an average single-cover

estimate for that month. At the end of the season, the plots

were also rated for a maturity index (MI), which indicates the

qualitative condition of plot in relation to a harvestable sod crop.

All treatments were replicated four times. Data from each mea-

surement date were analyzed by analysis of variance procedures

of the split-split-plot model.

FINDINGS

Weather during the first four weeks of the experiment se-

verely hindered the growth of all the plots. Over 14 in. of rain

fell at the research station during the month of June and tem-

peratures were cooler than normal. However, within four to five

weeks of establishment, the plots were actively growing and

excellent growing conditions continued throughout the remain-

der of the experiment.

The analysis of variance for each evaluation date indicated

a significant effect of cultivar and GroWin® and a significant

cultivar x GroWin® interaction. There were no significant ef-

fects of fertilizer application method (foliar vs. granular) and

no effects of N rate across the entire test (data not shown). The

lack of fertility response continues to support the working hy-

pothesis that zoysiagrass does not respond favorably to N fer-

tilization during the establishment phase. Prior to the study, it

was predicted that more aggressive cultivars such as ‘El Toro’

and ‘Cavalier’ would respond more favorably to N fertility than

the slow-growing ‘Meyer’, but this was not the case, as there

was no cultivar x N rate interaction for any measurement (data

not shown). Based on this analysis of variance, the remaining

discussion will focus on the cultivar x GroWin® effects.

A significant effect of cultivar was seen at all evaluation

dates, with ‘Cavalier’ being the most aggressive cultivar at all

dates, followed by ‘El Toro’ and ‘Meyer’ (Fig. 1). This was a

surprising finding since ‘El Toro’ is generally considered a more

aggressive species (Gibeault and Cockerham, 1988). A possible

explanation may be the difference in sprigs of ‘Cavalier’ and

‘El Toro’. ‘Cavalier’ is a Z. matrella cultivar and is a very fine-

textured, dense species, with a higher stolon / rhizome number

per unit area and shorter stolon and rhizome internode length

than ‘El Toro’. These key morphological features dictate that a

higher number of growing points (stolon and rhizome nodes)

would be obtained from a bushel of sprigs of ‘Cavalier’ than a

bushel of sprigs of ‘El Toro’. As such, early establishment would

be greater, as seen is Fig. 1, since a higher number of plants

would be established using equal numbers of sprigs. Work to

establish the numbers of potential growing points per bushel of

sprigs for the three cultivars tested is underway. ‘El Toro’ did

move quickly ahead of ‘Meyer’ at later establishment dates and

was almost equal to ‘Cavalier’ at the end of the season (Fig. 1),

suggesting that if planting rates were equivalent, ‘El Toro’ would

likely be the most aggressive cultivar, as expected.

Across all cultivars, GroWin® provides a small, but sig-

nificant effect on establishment from sprigs (data not shown).

These effects were not evident until 90 and 120 DAP, but the

overall increases were less than 10%. To analyze the cultivar x

GroWin® interaction, analysis of variance was conducted on

each cultivar to test the effects of various GroWin® treatments.

‘Cavalier’ was not affected by amending the soil with GroWin®

at any application date (Fig. 2). However, ’El Toro’ did show a

significant response to both a low (25 lb) and high (50 lb) rate

of GroWin® at 60, 90, and 120 DAP (Fig. 2). This supported

the hypothesis that the more aggressive cultivar, ‘El Toro’, might

respond more favorably to soil amendments or nutritional in-

crease. ‘Meyer’ zoysiagrass responded slightly to the high rate

of GroWin® at the first observation period, but this significant

difference had disappeared by the 90 DAP evaluation (Fig. 2).

Prior to the completion of this study, it was observed that

percent turf coverage may not fully reflect the ultimate goal of

these experiments, which was to establish a functional turf or

harvestable sod. In zoysiagrass, as maturity of the turf increases,

the leaf blades on the grass become very erect and produce a

smooth, stiff surface. At the end of the growing season, two

visual estimations of maturity, referred to as the maturity index

(MI), were taken to ascertain the condition of the plots in rela-

tion to a completely mature turf, not just percent turfgrass cover.

In relation to MI, there were significant differences in both cul-

tivar and GroWin® applications, with ‘Cavalier’ producing the

most mature turf, followed by ‘El Toro’ and ‘Meyer’ (Fig. 3). A

GroWin® x cultivar interaction was also observed relative to

maturity index. ‘Cavalier’ turf produced a near-mature turf in

the first growing season, regardless of GroWin® rates, while

both ‘Meyer’ and ‘El Toro’ responded favorably to applications

of GroWin® when rated for MI. (Fig. 3).

In summary, GroWin® produced slight but significant re-

sponses to hasten the establishment of zoysiagrass from sprigs.

Nitrogen fertility rates or application methods had no effect on

the establishment rates of the plots, similar to earlier work. These

findings further clarify that zoysiagrasses are a very low-input

option for a range of turf situations.

LITERATURE CITED

Carroll, M.J., P.H. Dernoeden, and J.M. Krouse. 1996.

Zoysiagrass establishment from sprigs following application

of herbicides, nitrogen, and a biostimulator. HortScience

31:972-975.

Fry, J.D. and P.H. Dernoedon. 1987. Growth of zoysiagrass from

vegetative plugs in response to fertilizers. J. Amer. Soc. Hort.

Sci. 112:285-289

Gibeault, V.A. and S.T. Cockerham. 1988. ‘El Toro’ zoysiagrass.

Cal. Turf. Culture 38:1

Henry, J.M., S. Tjosvold, and V.A. Gibeault. 1988. Zoysiagrass

establishment. Calif. Turfgrass Culture 38:1-4.

McCarty, B., G. Landry, Jr., J. Higgins, and L. Miller. 1999.

Sod production in the southern United States. Clemson Univ.

66

AAES Research Series 483

Coop. Ext. Serv. Circ. 702.

Richardson, M.D. and J.W. Boyd. 2001. Establishing Zoysia

japonica from sprigs. HortScience (in press).

Richardson, M.D., K.L. Hensler, and J. Elliot. 1999. Effects of

mycorrhizal inoculants on creeping bentgrass establishment. In

J.R. Clark and M.D. Richardson (eds.), Horticultural Studies

1998, Arkansas Ag. Expt. Stn., Res. Series 466, pp. 81-83.

Fig.1. Establishment rate of three zoysiagrass cultivars from sprigs. Letters at each date that are different indicate a

significant difference (P<0.05) in cover rate due to cultivar for that observation period.

Table 1. Fertilizer treatments applied to plots throughout the growing season.

Application rate

Treatment Application method Application interval (lb N /1000 ft2 / application)

1 control control control

2 foliar 1 week 0.0625

3 foliar 1 week 0.125

4 foliar 1 week 0.188

5 granular 4 weeks 0.25

6 granular 4 weeks 0.50

7 granular 4 weeks 0.75

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Horticultural Studies 2000

Fig. 2. Establishment rate of three zoysiagrass cultivars from sprigs, as affected by various levels of organic

amendment applied prior to sprigging. Letters within each cultivar at each date that are different indicate a significant

difference (P<0.05) in cover rate due to amendment for that observation period.

Fig. 3. Maturity index at the end of the growing season for three zoysiagrass cultivars, as affected by various levels of

organic amendment applied prior to sprigging. Letters within each cultivar indicate a significant difference (P<0.05) in

maturity due to amendment.

68

AAES Research Series 483

PERFORMANCE OF CREEPING BENTGRASS

CULTIVARS IN ARKANSAS: 1999-2000 REPORT

Michael D. Richardson1, John W. Boyd2, and Jeff Elliot3

IMPACT STATEMENT

A creeping bentgrass cultivar trial was established in Little

Rock, Ark., in the spring of 1998 to evaluate 19 bentgrass culti-

vars under typical putting green conditions. Conclusions from

this study are that the recently released bentgrass cultivars

Crenshaw, G1, Century, Grand Prix, Imperial, A4, and G2 are

well adapted to Arkansas growing conditions and may be used

for new golf course development and renovation.

BACKGROUND

Creeping bentgrass remains the grass of choice for putting

greens in the northern United States and throughout the transi-

tion zone where warm and cool season turfgrasses can be grown.

This species is noted for its adaptation to close mowing, high

shoot density, and superior putting quality. In recent years, a

large group of new bentgrass germplasm has been developed

by plant breeders in the U.S. This germplasm has been selected

for characteristics such as overall turf quality and performance,

heat tolerance, disease resistance, and salinity tolerance. With

the continued growth of the golf industry in Arkansas, and the

widespread construction and renovation of golf courses in the

state, a critical evaluation of these new cultivars under Arkan-

sas conditions was needed.

RESEARCH DESCRIPTION

A replicated variety trial was established on 23 March 1998

at Chenal Country Club (CCC) in Little Rock, Ark. The green

on which the test was established had been constructed accord-

ing to United States Golf Association (USGA) specifications in

the fall of 1997 and had remained fallow until the spring of

1998. Each plot was 4 x 8 ft and was individually hand-seeded

at a rate of 0.5 lb/1000 ft2. An organic fertilizer (Hou-Actinite,

6-3-0) was incorporated with the seed at a rate of 0.75 lb N/

1000 ft2. The experimental design was a randomized complete

block design with three replications of each cultivar.

Fertilization and pest control of plots were done according

to routine practices used on the remainder of the greens at CCC.

Approximately 1 lb of N/1000 ft2 was added to the plots monthly

during the first three months after establishment of the experi-

ment and approximately 0.25 lb of N/1000 ft2 per month during

the growing season. A preventative fungicide program was fol-

lowed to prevent diseases such as brown patch and pythium

and to control algae. The program included alternating applica-

tions of Daconil Ultrex (2 oz/1000 ft2) and Alliette/Fore (4 oz/

6oz per 1000 ft2) every 14 days. From June-September,

Dursban was applied at 0.75 oz/1000 ft2 every 28 days to

prevent cutworms.

Germination and establishment of the plots and turf qual-

ity during the establishment year were reported earlier

(Richardson et al., 1999). Turfgrass quality ratings, which were

taken periodically through the 1999 and 2000 growing seasons,

are reported here. Data were subjected to analysis of variance

and means were separated using least significant difference

(LSD) (P<0.05).

FINDINGS

Over the 3 years of the test, there have been several culti-

vars that have consistently rated very good in this evaluation.

These included ‘Crenshaw’, ‘G1’, ‘Century’, ‘Grand Prix’, ‘Im-

perial’, ‘A4’, and ‘G2’ (Tables 1, 2, and 3). Although several of

these cultivars ranked low during the first year of the test

(Richardson et al., 1999), they improved significantly after the

establishment period. Several of the cultivars that performed

best at CCC were those that were developed by Texas A&M

University under high temperature conditions, including

‘Crenshaw’, ‘Century’, and ‘Imperial’. One cultivar from that

program that did not perform well was ‘Cato’ (Tables 1, 2, and

3). This is surprising, since it has performed adequately in other

cultivar trials conducted by the National Turfgrass Evaluation

Program (Morris, 1998). In addition to the Texas A&M

bentgrasses, several of the new high-density bentgrasses from

Pennsylvania State University improved as these plots matured,

including ‘G1’, ‘G2’, and ‘A4’ (Tables 1, 2, and 3). The con-

sistency of these cultivars over the last 2 years of the study

suggests that these cultivars can be managed effectively in

this region.

In summary, a number of improved bentgrass cultivars are

well-adapted to the Arkansas region and produce a much higher

quality than standards such as ‘Penncross’ and ‘SR 1020’. These

cultivars will provide superintendents the opportunity to pro-

duce superior playing surfaces for their clientele.

1 Department of Horticulture, Fayetteville

2 Cooperative Extension Service, Little Rock

3 Chenal Country Club, Little Rock

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Horticultural Studies 2000

LITERATURE CITED

Richardson, M.D., K.L. Hensler, J.W. King, J.W. Boyd, and J.

Elliot. 1999. Performance of creeping bentgrass cultivars in

Arkansas, 1998 report. In J.R. Clark and M.D. Richardson

(eds.). Horticultural Studies 98. Ark. Agri. Expt. Station Res.

Series 466:87-89.

Morris, K.N. 1998. National Turfgrass Evaluation Program.

1993 National Bentgrass Test. U.S. Department of Agricul-

ture. NTEP No. 98-12. Beltsville, MD.

Table 1. Turf quality ratings by month of creeping bentgrass cultivars in Little Rock, Ark. - 1999 data.

Cultivar April May June July Aug. Oct.

Turf Qualityz

Crenshaw 7.3 7.7 8.0 7.7 7.3 7.7

G1 7.5 8.0 8.5 8.0 7.0 7.5

Century 7.3 7.3 7.7 7.7 7.7 7.3

Grand Prix 7.0 7.0 7.7 7.7 7.3 7.3

Imperial 6.3 7.3 7.3 7.0 7.3 7.3

A4 6.0 7.3 7.7 7.3 7.3 7.7

G2 7.0 6.7 6.7 7.0 7.0 6.7

SR 1020 6.3 6.0 5.7 5.7 6.0 6.3

SR 1119 5.3 5.0 5.3 6.3 6.7 5.7

Princeville 5.7 5.7 6.0 6.3 6.0 6.7

G6 4.3 5.3 5.7 6.0 5.7 5.7

L93 5.7 5.7 5.7 5.7 5.7 6.3

Providence 4.3 5.0 6.0 5.3 4.7 5.7

Trueline 5.0 4.7 5.0 5.3 5.0 5.3

Viper 4.7 5.0 5.3 5.0 4.7 5.3

Cobra 4.7 4.7 4.7 4.7 4.7 5.7

Penncross 5.7 5.0 4.7 4.3 4.0 5.0

Putter 4.0 4.7 5.0 5.0 5.0 5.3

Cato 3.3 4.3 4.7 5.0 4.7 5.0

LSDy(0.05) 1.5 1.4 1.6 1.2 1.3 1.4

z Quality rating of 1 to 9, with 9 = highest quality.

y Least significant difference between means at P< 0.05.

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AAES Research Series 483

Table 2. Turf quality ratings by month of creeping bentgrass cultivars in Little Rock, Ark. - 2000 data.

Cultivar Mar May June July Aug. Oct.

Turf Qualityz

Crenshaw 6.7 7.7 7.7 7.7 7.3 7.7

G1 8.5 7.9 8.0 8.0 7.0 7.5

Century 5.7 7.3 7.8 7.7 7.7 7.7

Grand Prix 6.0 7.3 8.0 7.7 7.3 7.3

Imperial 6.7 7.3 7.8 7.0 7.3 7.3

A4 6.7 7.0 7.8 7.3 7.3 7.3

G2 6.3 7.3 8.2 7.0 7.0 7.7

SR 1020 6.3 6.3 7.2 5.7 6.0 6.0

SR 1119 6.3 5.3 6.7 6.3 6.7 6.7

Princeville 6.3 6.3 6.8 6.3 6.0 6.7

G6 5.0 6.0 7.0 6.0 5.7 6.3

L93 6.7 5.7 6.3 5.7 5.7 6.3

Providence 6.0 5.0 6.3 5.3 4.7 5.3

Trueline 7.3 5.3 5.8 5.3 5.0 5.7

Viper 5.7 5.0 6.2 5.0 4.7 5.3

Cobra 7.0 5.3 6.3 4.7 4.7 5.7

Penncross 7.0 5.7 5.3 4.3 4.0 5.0

Putter 6.3 4.7 6.7 5.0 5.0 5.7

Cato 6.3 4.3 6.5 5.0 4.7 5.7

LSDy(0.05) 1.2 1.2 0.7 1.1 1.3 1.3

z Quality rating of 1 to 9 with 9 = highest quality.

y Least significant difference between means at P<0.05.

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Horticultural Studies 2000

Table 3. Turf quality ratings by month of creeping bentgrass cultivars in Little Rock, Ark. - 1998-2000 average data.

Cultivar 1998 avg. 1999 avg. 2000 avg. 3yr avg.

Turf qualityz

Crenshaw 6.9 7.6 7.4 7.3

G1 6.1 7.8 7.8 7.2

Century 6.7 7.5 7.3 7.2

Grand Prix 6.1 7.3 7.2 6.9

Imperial 6.2 7.1 7.2 6.8

A4 5.7 7.2 7.2 6.7

G2 6.0 6.8 7.2 6.7

SR 1020 5.6 6.0 6.2 6.0

SR 1119 5.7 5.7 6.3 5.9

Princeville 4.9 6.1 6.4 5.8

G6 5.3 5.4 6.0 5.6

L93 4.7 5.8 6.2 5.6

Providence 5.4 5.2 5.4 5.3

Trueline 5.1 5.1 5.7 5.3

Viper 5.5 5.0 5.3 5.3

Cobra 5.0 4.9 5.6 5.2

Penncross 5.1 4.8 5.2 5.0

Putter 4.6 4.8 5.5 5.0

Cato 4.1 4.5 5.3 4.7

LSDy (0.05) 0.8 1.1 0.8 0.7

z Quality rating of 1 to 9 with 9 = highest quality.

y Least significant difference between means at P<0.05.

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AAES Research Series 483

UNIVERSITY OF ARKANSAS PLANT

EVALUATION PROGRAM:

1999 PLANTS/2000 REPORT

James Robbins1 and Jon T. Lindstrom2

IMPACT STATEMENT

A plant evaluation program was initiated in Arkansas in

1999 with the purpose of evaluating new or underutilized orna-

mental plants on a statewide basis. This report summarizes the

year 2000 results for the first group of plants planted in the

spring of 1999.

BACKGROUND

Plant evaluation programs are important because they pro-

vide valuable information on the adaptability of specific plants

to a more localized region. The University of Arkansas pro-

gram is unique among university programs in that it includes

multiple sites that represent three USDA cold hardiness zones.

The program also differs from many other programs in that it

uses more than one plant at each test site and collects quantita-

tive data in addition to standard, qualitative observations. Infor-

mation collected from this program will be invaluable in select-

ing and marketing ornamental plants adaptable to Arkansas.

RESEARCH DESCRIPTION

The current team of cooperators includes Dr. Jim Robbins,

Dr. Jon Lindstrom, Dr. Gerald Klingaman, Mr. Scott Starr, Dr.

James Cole, Ms. Manjula Carter, Mr. Matthew Pelto, and Ms.

Janet Carson.

The program uses three test sites: the Southwest Research

and Extension Center at Hope (USDA cold hardiness zone 8a),

the University of Arkansas’ Cammack property in Little Rock

(zone 7a), and the Arkansas Agricultural Research and Exten-

sion Center at Fayetteville (zone 6 b). The three test sites have

similar environmental and cultural characteristics. Full sun plants

were grown in row-type beds 3 ft wide with a 7 ft grass alley.

Plants groups are planted together (i.e. trees are planted together,

etc.). Trees are spaced 10 ft apart, shrubs 6 ft apart, and herba-

ceous perennials 4 ft apart. Initial plant size is provided for each

entry in the discussion. For shade-requiring plants, separate

evaluation sites were established under natural shade at all three

test sites. The Little Rock site was planted on 10 March; the

Fayetteville site was planted on 11 March; the Hope site was

planted on 13 April—all in 1999. Irrigation at all three sites is

by a drip system. Plants were fertilized and mulched after plant-

ing. Postemergence herbicides were used at all three test sites.

No disease or insect control was implemented in 1999 or 2000.

In both years, the oak and Styrax were pruned following final

growth measurements to establish a tree-like habit. Pruning con-

sisted of removing the bottom one-third of limbs. Final growth

measurements for all entries were taken at Little Rock on 2

Nov., Fayetteville on 19 Oct., and Hope on 30 Nov. Results

discussed in this report are from the second year of the trial.

FINDINGS

In general, the best growth for the 15 shrubs and two trees

continues to be at the Little Rock site. Plants at the Little Rock

site receive a few hours of shade generally during the morning

hours. Whereas sites at Fayetteville and Hope are very exposed,

full-sun sites. The Fayetteville site also has consistent wind expo-

sure. Arkansas experienced an extremely hot and dry summer

at all three sites in 2000 (Figs. 1 and 2). For example, at Little

Rock, the average high temperature during the month of

August was 102° F, or 12 degrees above normal.

Rhododendron Autumn AmethystTM (3-gal pots at planting)

Performance was good at all sites. Flowers were first noted

in early March and continued through mid-April. Significant

re-bloom was observed in late August and continued until each

site had a hard freeze. The plant appears to be slightly wider

(40 in.) than tall (29 in.). This is the tallest of the three

Encore™ azaleas being evaluated. The largest increase in growth

for 2000 was in Little Rock with Fayetteville a close second.

Rhododendron AutumnCoralTM (3-gal pots at planting)

Performance was good at all sites. Flowering notes indi-

cate that Autumn Coral™ started flowering 1 week after

Autumn Amethyst™ in the spring, but flowered for a similar

period of time. Significant re-bloom was noted in mid-July and

continued until each site had a very hard freeze. Plant habit was

clearly wider (31 in.) than tall (16 in.). Habit of Autumn

Coral™ is very similar to Autumn Embers™.

Rhododendron Autumn EmbersTM (3-gal pots at planting)

Performance was good at all sites. Spring flowering period

is very similar to Autumn Coral™. Summer/fall rebloom began

a little later than Autumn Amethyst™ and Autumn Coral™.

Overall shape is similar to Autumn Coral™ (33 in. wide x 17

in. tall).1Cooperative Extension Service, Little Rock

2Department of Horticulture, Fayetteville

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Horticultural Studies 2000

Camellia sasanqua Hot FlashTM (3-gal pots at planting)

Performance was good at all sites. First flowers opened in

mid-December, 1999. The flowers color have a deep rose color.

Plant shape is slightly wider (27 in.) than tall (21in.). The over-

all size at each of the three sites is very similar and consistent

after 2 years.

Ilex x Little RedTM (5-gal pots at planting)

Performance was good at all test sites. The plant is slightly

taller (76 in.) than it is wide (63 in.). This plant has good land-

scape qualities with the burgundy color of emerging foliage,

clean foliage, and 5-6 mm red fruits.

Ilex x OakleafTM (5-gal pots at planting)

Performance was good at all test sites. The plant was taller

(85 in.) than wide (34 in.). A strong pyramidal shape is devel-

oping without shearing. This holly lends itself well to a narrow

screen or hedge plant.

Ilex x Dixie DreamTM (7-gal pots at planting)

Significant flowering was noted in late May and early June.

Significant fruit production was noted starting in October. The

fruits of this cultivar are smaller than Little Red™. Performance

was good at all test sites. Plants have an upright pyramidal shape

(53 in. tall by 39 in. wide) without pruning.

Abelia x grandiflora Sunrise® (3-gal pots at planting)

Performance was good at Little Rock and Fayetteville.

Abelia continues to struggle at Hope. Flowering began in mid

June and continued sporadically into fall. Significant reversion

from the variegated form back to a green-leafed form was noted

thus the variegation does not appear to be stable. Average plant

width (35 in.) was twice the height (17 in.). Based on perfor-

mance and reversion problems, this cultivar will likely not be

recommended.

Ligustrum ‘Green Meatball’ (5-gal pots at planting)

Performance was good at all sites. In last year’s report we

noted the plants developed a wispy, open habit at all three sites.

Plant habit has changed significantly this year. The plant devel-

oped tremendous vertical growth last year but filled that growth

in this year. The shape is approaching a ball in the second year

(59 in. wide x 52 in. tall). Peak flowering was noted in May.

Itea virginica ‘Henry’s Garnet’ (1-gal pots at planting)

Performance was good at all sites. Flowering generally be-

gan at the end of April and continued for one month. A real

asset to this plant is the rich maroon fall color that is most

intense by late November. Plants are beginning to spread quickly

by rhizomes. Average plant size was 28 in. tall by 52 in. wide.

Rhaphiolepis indica Bay Breeze® (1-gal pots at planting)

Performance was good at all sites. Flowering began in early

April and flowered again in late summer. It did not flower at

Fayetteville this year. The plant developed a very attractive deep-

maroon winter foliage color that makes a nice backdrop for the

light pink flowers in early spring. Plant habit is clearly spread-

ing (28 in.) rather than tall (13 in.). The most significant growth

increase this year was at Hope, followed by Little Rock, and

then Fayetteville. The largest plants continue to be at Little Rock.

Foliar leaf spot was noted on the plants.

Loropetalum chinense Plum Delight® (1-gal pots at planting)

Performance was mixed again this year. Plants grew vigor-

ously in Little Rock but struggled at Fayetteville and Hope.

For some unknown reason three-quarters of the plants at Hope

died this growing season and one-quarter died at Fayetteville.

Plant color was a deep rich-maroon in Fayetteville but was a

more washed-out brown-purple at the other two sites. The fact

that Hope and Fayetteville are very open, full-sun sites sug-

gests Loropetalum would benefit from some sun protection at

some point during the day. Flowering began in late February

and continued until a hard late spring freeze. Plants tend to throw

late-season flowers based on temperatures and precipitation.

When in flower this plant is very attractive. Loropetalum did

not flower at Fayetteville this year. Plants at Little Rock are

enormous considering the age and size of the original plant.

Average width was 106 in. x 59 in. tall at Little Rock. Plants are

considerably smaller at Hope and Fayetteville.

Lagerstroemia x ‘Pocomoke’ (liners used at planting)

Considering the small size of the initial liners, this cultivar

had remarkable growth and performance for field-planted

conditions. Flowers started to appear in early July and peaked

toward the end of August. Plants continue to flower into Sep-

tember. Of the two genetic dwarfs being tested, this appears to

be the best. Average size is 23 in. wide by 12 in. tall.

Lagerstroemia x ‘Chickasaw’ (liners used at planting)

Like ‘Pocomoke’, considering the size of the initial liners,

it is amazing what growth and plant survival occurred.

‘Chickasaw’ was very tentative as flower buds developed. Beau-

tiful, glossy, red ceramic flower buds appeared in July but were

slow to open until late August or into early September. Buds

almost appeared “blind” as the petals barely emerged from the

calyx. The overall impact of the flower display was not as good

as that seen with ‘Pocomoke’. Average size was 13 in. wide by

9 in. tall.

Lagerstroemia indica ‘Velma’s Royal Delight’ (liners used at

planting)

This crapemyrtle began flowering in mid-June and contin-

ued through (mid-September). Performance at Fayetteville is

extremely impressive considering the duration of flowering,

flower color, and plant size. Powdery mildew was noted at the

Little Rock location. Average size is 30 in. wide by 23 in. tall.

Styrax japonicus (5-gal pots used at planting)

Growth was good at all test sites. Dramatic flowering is

from mid-April to early May. Again this year at the Fayetteville

site, scorching of the foliage was apparent in mid August due to

the extended hot and dry weather. Growth increases were very

similar at all test sites. One minor problem is the appearance of

basal watersprouts and suckers that would require constant re-

moval to maintain a clean landscape appearance. The average

plant height was 114 in. with a trunk diameter at 6 in. of height

just over 2 in.

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AAES Research Series 483

Quercus hybrid (1-gal pots used at planting)

A preliminary assessment is that this plant is Quercus x

comptoniae. (Q. lyrata x Q. virginiana). Growth was good at

all sites. Since this plant is of seed origin, the plant habits are

beginning to fall into two categories. One group is developing a

desirable open tree canopy, while those in the second group

show a strong tendency to produce many recurving lower

branches that will make this plant difficult to work with and

require more initial pruning. The average plant height was 107

in. with a trunk diameter at 6 in. of height just under 2 in.

ACKNOWLEDGMENTS

The ornamentals team would like to express their sincere

appreciation to the cooperating nurseries—Flowerwood

Nurseries, Hines Nurseries, Greenleaf Nursery, Morningside

Nursery, and Pittman Nursery—for donating the plants, and to

the Arkansas Nurserymen’s Association for financial support.

75

Horticultural Studies 2000

EFFECT OF LINER AGE ON SUBSEQUENT

GROWTH IN CONTAINER PRODUCTION

James Robbins1 and Steven Wiest2

IMPACT STATEMENT

An issue for nurseries growing liners (plants between propa-

gation and a salable plant) is the effect of carryover, or liners

not sold in their first marketing year, on long-term growth of

a finished container (plant ready for sale). Results from

this experiment suggest that 2-year liners are just as salable as

1-year liners.

BACKGROUND

Container grown liners are the primary source for finished

container grown plants. Most nurseries that grow container

grown liners grade them prior to potting based primarily on

plant age or size. Morningside Nursery, Morrilton, Ark., is a

major supplier of crape myrtle liners for the United States. In

most cases, crape myrtle cuttings are taken in May or June with

a finished liner being sold the following spring. This is referred

to as a 1-year liner. Liners that are held over an additional win-

ter are referred to as a 2-year liner. Usually, Morningside Nurs-

ery sells only 1-year liners and disposes of carryover crops. Their

concern is that 2-year liners result in a poorer quality finished

container grown plant. While studies (Keever and Cobb, 1987;

Klingaman and King, 1983) have demonstrated an effect of

container size on performance after planting, research has not

been conducted that evaluates the effect of liner age on finished

stock plant performance. This research was conducted to de-

termine whether 2-year liners of crape myrtle are inferior to

one-year liners.

RESEARCH DESCRIPTION

Five cultivars of crape myrtle liners were sorted by the

Morningside Nursery staff in May 2000 into 1-year-old and 2-

year-old plants. Both of these groups of liners had been grown

in 2 in. liner pots. Liners were transported to Fayetteville, then

transplanted into finished one-gallon containers on 25 May 2000.

Potting medium was a Strong-lite High Porosity potting soil

and plants were topdress fertilized with Multicote 17-5-12 (10-

12 month) at the rate of 13 gm/pot. Plants were placed on a

gravel bed and watered as needed. Containers were placed in a

completely randomized design with five single plant replica-

tions.

All plants of the cultivar Muscogee were used to estimate

root dry weight. The root system was carefully washed before

being dried in a forced air oven at 58oC for 2 days and then

weighed. Mean dry weight of roots from the 2-year-old and 1-

year-old ‘Muscogee’ plants were 2.8 g and 1.0 g, respectively.

At the end of the growing season (2 Nov. 2000) dry weights

of roots and shoots of other cultivars were measured.

FINDINGS

Root and shoot growth of Dynamite™ liners was greater

than that of all other cultivars, and shoot growth of ‘Zuni’ liners

was significantly less than that of other cultivars (Table 1).

Importantly, these differences were independent of liner age

since statistical analysis indicated no significant cultivar by age

interaction for either shoot or root growth. Root and shoot

growth of both 1-year and 2-year liners were indistinguishable

(Table 2).

Based on these results it appears that Morningside Nursery

can sell 2-year liners and feel confident that their customers

will grow plants sized similarly to “new” liners. Although car-

rying liners over is not desirable from the standpoint of the ad-

ditional cost of handling these plants through two winters, it

does offer nurseries the option to use this older liner crop to fill

orders when “new” inventory is limited.

LITERATURE CITED

Keever, G.J. and G.S. Cobb. 1987. Effects of container vol-

ume and fertility rate on growth of two woody ornamentals.

HortScience 22:891-893

Klingaman, G.L. and J.H. King. 1983. What size and shape of

container are best for growing seedlings? American Nurs-

eryman 157:87-93

1Cooperative Extension Service, Little Rock

2Department of Horticulture, Kansas State University

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AAES Research Series 483

Table 1. Final shoot and root dry weight of finished one-gallon crape myrtle cultivars.

Cultivar Final shoot dry wt. Final root dry wt.

Dynamite™ 26.0 az 17.8 a

Tuscarora 17.2 b 11.5 b

Tonto 18.0 b 9.2 b

Zuni 9.3 c 8.0 b

z Numbers within a column followed by the same letter are not significant at P<0.05.

Table 2. Effect of age on final shoot and root dry weight of finished one-gallon crape myrtle plants.

Liner age Final shoot dry wt. Final root dry wt.

One-year-old 17.2 az 11.3 a

Two-year-old 18.0 a 11.9 a

z Numbers within a column followed by the same letter are not significant at P<0.05

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Horticultural Studies 2000

INCIDENCE AND CONTROL OF LOCALIZED

DRY SPOT ON ARKANSAS PUTTING GREENS

Megan F. Thomas and Douglas E. Karcher1

IMPACT STATEMENT

Localized dry spot (LDS) is a hydrophobic soil condition

of unknown cause that affects putting green turf. Recently, it

has become a significant management problem for golf course

superintendents. Arkansas putting greens are particularly sus-

ceptible to LDS since they are typically established with cool-

season turfgrasses and often experience high temperature and

moisture stress extremes. A survey was conducted to assess the

incidence and severity of LDS on Arkansas putting greens and

to determine if LDS occurrence was correlated with putting

green characteristics. In addition, a study was performed to de-

termine if a commercially available wetting agent was effec-

tive in curing a putting green that was severely afflicted with

LDS. Although survey data is still being collected, LDS ap-

pears to be a significant problem in the state of Arkansas as

69% of the respondents reported that they had experienced at

least moderate LDS. Wetting agent treatments increased water

infiltration, but had no effect on soil moisture. This was prob-

ably the result of the wetting agent binding to the thatch layer.

BACKGROUND

The United States Golf Association (USGA) developed a

putting green construction method in the early 1960s that re-

quires a 12 in. root zone composed predominantly of sand. To-

day, this is the most widely used method of constructing put-

ting greens in the United States (USGA, 1993). The sandy root

zone is resistant to compaction and provides adequate water

infiltration, drainage, and exchange of atmospheric gases. How-

ever, a major disadvantage of sandy root-zone putting greens

is the frequent occurrence of localized dry spot (Karnok et

al., 1993).

Localized dry spot is a hydrophobic soil condition that can

lead to major turf damage via moisture stress, and often results

in dead patches of turf (Wilkinson and Miller, 1978). Prolonged

periods of high temperature accompanied by little rainfall in-

crease the likelihood of LDS on putting greens in the southern

United States. Furthermore, the cause of LDS is not well under-

stood and a consistent, dependable control for LDS on putting

greens does not exist.

One objective of the following research was to evaluate

the severity of LDS throughout Arkansas and to determine if

LDS occurrence was correlated to putting green characteristics

through a state-wide survey. A second objective was to deter-

mine the effects of a commercial wetting agent on a putting

green that was severely afflicted with LDS.

RESEARCH DESCRIPTION

LDS Survey. An administered questionnaire was used to

correlate the occurrence of LDS in Arkansas with several put-

ting green characteristics. The survey was mailed to 96 golf

course superintendents in Arkansas in an attempt to evaluate

LDS severity and its relationship to putting green age, soil pH,

depth of thatch layer, and sun exposure throughout the state. As

of now only 16 superintendents have responded to the survey,

but data collection is still in progress.

Wetting Agent Study. A wetting agent study was conducted

at the University of Arkansas Agricultural Research and Exten-

sion Center (Fayetteville) on a ‘Crenshaw’ creeping bentgrass

putting green built to USGA-specifications (USGA, 1993). The

commercial wetting agent Aqueduct advertised as a curative

treatment for LDS, was compared against control plots for its

ability to remedy LDS patches on the experimental putting green.

The first treatment of Aqueduct was applied at a rate of 8 oz/

1000 ft2 to five individual LDS patches on 2 Aug. 2000. An

equal number of patches were left untreated for controls. Indi-

vidual plot dimensions were 1 ft by 1 ft.

Soil moisture and water infiltration rates were periodically

measured on all plots following Aqueduct application. Soil mois-

ture was measured with portable time domain reflectometry

(TDR) probes. Water infiltration times were measured by plac-

ing 5 ml of water on each dry patch with a syringe and record-

ing how many seconds until the droplet had completely infil-

trated the turf surface. Due to the relatively small size of the

plots, a concern developed that the channels created by the TDR

probes might have affected the infiltration times. To accommo-

date both soil moisture and infiltration time evaluations, the

experiment was repeated using larger plot dimensions (2 ft by 2

ft). In the second run of the experiment, the same rate of Aque-

duct was applied to four plots on 18 Aug. 2000 and again on the

same plots on 31 Aug. 2000. An equal number of plots were left

untreated as a control.

1Both authors are associated with the Department of Horticulture, Fayetteville

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AAES Research Series 483

FINDINGS

LDS Survey. Of the 16 golf course superintendents who

returned the completed survey 38% rated LDS as a severe man-

agement problem, while 69% rated LDS as at least a moderate

problem. The putting greens represented by the survey responses

varied widely in age, soil pH, duration of sun exposure, and

thatch accumulation. However, none of these characteristics

were correlated to the incidence of LDS (Fig. 1). Similar LDS

surveys conducted in Georgia (Tucker et al., 1990) and the

United Kingdom (York, 1993) have also demonstrated no rela-

tionship between LDS severity and putting green characteris-

tics. These results imply that the incidence of LDS may depend

on the interaction of several environmental and putting green

characteristics, making LDS occurrence difficult to predict and

control. Several additional completed surveys are anticipated

by the end of Spring 2001. As surveys are submitted, the entire

survey data set will be re-analyzed.

Wetting Agent Study. In both runs of the experiment,

wetting agent treatment had little effect on soil moisture (Figs.

1 and 2). However, water infiltration times were significantly

improved by wetting agent treatment in both runs of the experi-

ment (Figs. 1 and 2). In addition, some plots treated with Aque-

duct seemed to improve in color a few days after treatment, but

this was not consistently observed on all treated plots and color

data were not recorded.

These results suggest that the wetting agent may have been

mostly absorbed by the turfgrass thatch, resulting in little to no

improvement in moisture content of the underlying soil. In this

case, shorter infiltration times would be expected on plots treated

with wetting agents since a sufficiently small volume of water

was used in the evaluation (5 ml; small enough to be completely

adsorbed by the thatch). This experiment will be repeated using

a double ring infiltrometer that requires water to infiltrate

through the thatch and into the underlying soil.

Localized dry spot appears to be a significant problem in

Arkansas. The most commonly prescribed treatment for LDS,

wetting agents, have been noted to yield inconsistent results, as

was the case in this experiment. Research focusing on the precise

placement of wetting agents, directly at the site of hydrophobic

soil, may result in improved control of LDS in the future.

LITERATURE CITED

Karnok, K.A., E.J. Rowland, and K.H. Tan. 1993. High pH

treatments and the alleviation of soil hydrophobicity on golf

greens. Agron. J. 85:983-986.

Tucker, K.A., K.J. Karnok, D.E. Radcliffe, G. Landry Jr., R.W.

Roncadori, and K.H. Tan. 1990. Localized dry spots as caused

by hydrophobic sands on bentgrass greens. Agron. J. 82:549-

555.

USGA. 1993. USGA recommendations for a method of putting

green construction. USGAGreen Section Record. 31(2):4-5.

Wilkinson, J. F. and R. H. Miller. 1978. Investigation and treat-

ment of localized dry spots on sand golf greens. Agron. J.

70:299-304.

York, C.A. 1993. A questionnaire survey of dry patch on golf

courses in the United Kingdom. J. Sports Turf Res. Inst.

69:20-26.

Fig. 1. Survey data correlating the relationship between LDS severity (1=none, 9=severe) and a) putting green age,

b) soil pH, c) depth of thatch layer, and d) duration of sun exposure.

79

Horticultural Studies 2000

Fig. 2. Volumetric soil moisture and water infiltration times as affected by Aqueduct wetting agent. First run of experiment.

Fig. 3. Volumetric soil moisture and water infiltration times as affected by Aqueduct wetting agent. Second run

of experiment.

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AAES Research Series 483

Conversion Table

U.S. to Metric Metric to U.S.

multiply multiply

to convert from to U.S. unit by to convert from to metric unit by

length length

miles kilometers 1.61 kilometers miles .62

yards meters .91 meters yards 1.09

feet meters .31 meters feet 3.28

inches centimeters 2.54 centimeters inches .39

area and volume area and volume

sq yards sq meters .84 sq meters sq yards 1.20

sq feet sq meters .09 sq meters sq feet 10.76

sq inches sq centimeters 6.45 sq centimeters sq inches .16

cu inches cu centimeters 16.39 cu centimeters cu inches .06

acres hectares .41 hectares acres 2.47

liquid measure liquid measure

cu inches liters .02 liters cu inches 61.02

cu feet liters 28.34 liters cu feet .04

gallons liters 3.79 liters gallons .26

quarts liters .95 liters quarts 1.06

fluid ounces milliliters 29.57 milliliters fluid ounces .03

weight and mass weight and mass

pounds kilograms .45 kilograms pounds 2.21

ounces grams 28.35 grams ounces .04

temperature temperature

F C 5/9(F–32) C F 9/5(C+32)