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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
67
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
69
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.
72
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
73
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)
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