May 2011 Volume XV, Issue III

Inspector Findings

in Kentucky Office of the State Entomologist

www.KyStateEnt.org

Picture key: 1: Fire Blight on pear

flower cluster 2: Fire Blight shep-

herd’s crook 3: Periodical cicada

molting to an adult 4: bagworm 5:

brown marmorated stink bug Pic-

tures from www.insectimages.org

and KY Pest News

Inside this issue:

Crabapple Scale 2

Crabapple Fire Blight 4

Brown Marmorated

Stink Bug Damage

5

Winter Drying on

Broad-leaved

Evergreens

6

Periodical Cicada

Emergence

7

New Facebook Page 8

Page 2 Inspector Findings in Kentucky

Managing Flowering

Crabapple Scab

By John Hartman, Extension Plant Pathologist,

University of Kentucky

Kentucky flowering crabapples,

flowering now or soon to be in

bloom, are enjoyed for their pro-

fuse flowers and for their attrac-

tive foliage and fruit. Experienced

growers and homeowners are well

aware that springtime is also the

time of year that many of the im-

portant diseases of flowering crab-

apple are most active.

Many flowering crabapples are

made unsightly or are severely in-

jured by one or more of several

common diseases. In most years,

apple scab (Figure 1) is the most

damaging disease of susceptible

crabapples. Infected leaves (Figure

1) turn yellow (Figure 2) and drop

from the tree. Unless resistant

crabapples are selected and

grown, fungicide sprays used as a

disease preventative must be in-

cluded in the maintenance pro-

gram, especially for disease-

susceptible crabapples growing in

the nursery. Apple scab is espe-

cially problematic because some

cultivars are so susceptible that

trees can be defoliated by mid-

summer (Figure 3). In addition to

weakening the trees, scabbed

crabapples defoliated by summer

produce fewer blooms the next

spring.

Managing apple scab caused by

the fungus Venturia inaequalis.

• While trees are dormant, rake

up and destroy or chop up old, in-

fected, fallen leaves where the

fungus overwinters.

• Remove and destroy abandoned

apple and susceptible crabapples

growing near the nursery.

• On mature landscape trees, thin

out crabapple foliage by pruning

to allow improved ventilation and

sunlight penetration.

• Primary infections occur during

periods of prolonged leaf wetness

in spring. To prevent infections,

apply fungicides when the first

green shoot tips are showing in

early spring before flowers open

and repeat 3 or 4 times at two-

week intervals. Fungicide choices

include protectants containing in-

gredients such as mancozeb,

chlorothalonil, captan, or sulfur.

Eradicant fungicides contain

chemicals such as thiophanate-

methyl, propiconazole, myclobu-

tanil, triadimefon, or fenarimol.

• Nurserymen should be growing

scab-resistant crabapples and

landscapers and homeowners

should, for new plantings, insist on

use of scab-resistant or at least

scab-susceptible trees that do not

defoliate easily. Ratings vary from

one part of the country to an-

other, however disease resistant

or tolerant crabapples may include

the following:

Durably Resistant: The scab fun-

gus has overcome the genetic re-

sistance of many crabapple culti-

vars, but the durably resistant

crabapples listed here have with-

stood heavy scab pressure for

many years without resistance

breakdown. ‘Adirondack’,

‘Beverly’, ‘Jackii’, ‘Silver Moon’,

‘White Angel’, M. sargentii.

Resistant: Scab resistant trees

may become infected, but the

scab lesions don’t detract from the

tree’s appearance. ‘Adams’, ‘Bob

White’, ‘Brandywine’, ‘Callaway’,

‘Camelot’, ‘Candymint’,

‘Canterbury’, ‘Cinderella’,

‘Coralburst’, ‘David’, ‘Dolgo’,

‘Excalibur’, ‘Firebird’, ‘Foxfire’,

‘Golden Raindrops’, ‘Guinevere’,

‘Gwendolyn’, ‘Hamlet’, ‘Holiday

Gold’, ‘Jewelberry’, ‘King Arthur’,

‘Lancelot’, ‘Liset’, ‘Lollipop’,

‘Louisa’, ‘Manbeck Weeper’,

‘Ormiston Roy’, ‘Pink Princess’,

‘Prairiefire’, ‘Prairie Maid’,

‘Professor Sprenger’, ‘Purple

Prince’, ‘Rawhide’, ‘Red Jewel’,

‘Sinai Fire’, ‘Strawberry Parfait’,

‘Sugar Tyme’, ‘Tina’.

Susceptible: Although some of

these trees may become heavily

scabbed, they do not readily defo-

liate. ‘American Salute’, ‘American

Spirit’, ‘Canary’, ‘Donald Wyman’,

‘Doubloons’, ‘Harvest Gold’, ‘Mary

Potter’, ‘Molten Lava’, ‘Royal

Fountain’, ‘Sentinel’, ‘Silver Drift’,

‘Snowdrift’, M. floribunda.

• Avoid growing the following cul-

tivars in the nursery or landscape

because they may require added

management to avoid severe scab

outbreaks.

Very susceptible: ‘American

Beauty’, ‘American masterpiece’,

‘American, Triumph’, ‘Barbara

Ann’, ‘Centurion’, ‘Crimson Bril-

liant’, ‘Dorothea’, ‘Indian Magic’,

‘Katherine’, ‘Pink Perfection’, ‘Pink

Satin’, ‘Pink Spire’, ‘Radiant’, ‘Red

Jade’, ‘Red Silver’, ‘Red Splendor’,

‘Royal Ruby’, ‘Royal Scepter’,

‘Robinson’, ‘Royalty’, ‘Snow

Cloud’, ‘Spring Snow’,

‘Thunderchild’, ‘Weeping Candied

Apple’, ‘Vanguard’, ‘Velvet Pillar’,

‘White Cascade’, ‘Winter Gold’.

Extremely susceptible: ‘Almey’,

‘Eleyi’, ‘Hopa’, etc.

Figure 1. Crabapple leaf with sporulating lesions on the leaf surface in springtime.

Note that infections are more dense along the veins where there may have been

more leaf surface moisture needed for spore germination and leaf infection.

Figure 2. Older scab infection resulting in yellow crabapple leaves which will soon

drop. Dark spots on leaves are scab lesions.

Figure 3. Crabapple tree defoliated in mid-summer by scab disease. This tree had few blooms

the next spring.

Page 4 Inspector Findings in Kentucky

Kentucky flowering crabapples,

flowering now, are enjoyed for

their profuse flowers and for their

attractive foliage and fruit. Experi-

enced growers and homeowners

are well aware that springtime is

also the time of year that many of

the important diseases of flower-

ing crabapple are most active.

Many flowering crabapples are

made unsightly or are severely in-

jured by one or more of five com-

mon diseases—apple scab

(discussed in Kentucky Pest News

two weeks ago), fire blight, cedar-

apple rust, cedar-quince rust, and

powdery mildew. Injury due to fire

blight infection is often obvious in

the tree because in spring and

early summer, twigs and small

branches are dead and blackened.

Managing fire blight caused by the

bacterium Erwinia amylovora:

• While trees are dormant, prune

out shoots killed by fire blight the

previous year.

• Remove water sprouts and root

suckers when they are small.

• Remove nearby neglected pear

and apple trees from the nursery

or landscape because these trees

can be a source of overwintering

fire blight bacteria.

• Plant fire blight-resistant crabap-

ples in new plantings. Ratings vary

from one part of the country to

the other, however, the following

cultivars are thought to be more

tolerant of fire blight: ‘Adams,’

‘Adams Dwarf,’ ‘Callaway,’

‘Candied Apple,’ ‘Christmas Holly,’

‘David,’ ‘Dolgo,’ ‘Harvest Gold,’

‘Indian Summer,’ ‘Jewelberry,’

‘Liset,’ Malus sargentii, M. yun-

nanensis var. veichii, M. zumi

‘Calocarpa,’ ‘Pink Princess,’ ‘Pink

Spires,’ ‘Prairiefire,’ ‘Profusion,’

‘Radiant,’ ‘Red Baron,’ ‘Robinson

Dwarf,’ ‘Royalty,’ ‘Selkirk,’

‘Sentinel,’ ‘Spring Snow Dwarf,’

and ‘Velvet Pillar’.

• Antibiotic sprays such as strepto-

mycin can be used to protect open

flowers from infection. Antibiotic

sprays are best used in the nurs-

ery, and not in the landscape. Use

of a computer model such as

Maryblyt or Cougarblight for tim-

ing of fire blight sprays is most

useful.

• Nursery growers may consider

using the fire blight predictive sys-

tem available to apple growers on

the U.K. Ag Weather Center site

(http://wwwagwx.ca.uky.edu/

kymesonet2.html). The predictive

system works because the

weather and fire blight risk pa-

rameters are the same for apple

and crabapple. These predictive

systems have already indicated

that flowering crabapples with

open flowers were at high or ex-

treme risk for fire blight earlier

this week on both Saturday and

Monday. After flower petals fall in

the coming days, the risk of pri-

mary fire blight infections drops to

low levels. However, from primary

infections that already occurred,

secondary shoot infection symp-

toms will continue to appear for

the next several weeks.

• For all but the most susceptible

trees, infections are normally

halted by the tree before the bac-

teria actually kill the tree. Thus,

infected branches are best re-

moved in winter.

• Avoid promoting succulent

growth that favors fire blight.

Managing Flowering Crabapple Fire Blight

By John Hartman, Extension Plant Pathologist, University of Kentucky

Page 5 Inspector Findings in Kentucky

As the weather continues to warm

insects will become active soon, if

they are not already active. One

insect that we will be watching for

carefully is the brown marmorated

stink bug (BMSB) that was first

confirmed in Kentucky that past

fall. This new invasive insect pest

may be one of the more serious

insect pests in Kentucky in the

coming years as it has a very wide

host range attacking many field

and horticultural crops as well as

ornamental plants and is home

invader in the winter months. This

article describes the type of dam-

age and when it is likely to occur

on different field and horticultural

crops. While the most serious

damage is usually to the fruiting

parts of plants, they may also feed

on leaves and stems of some

hosts. As this pest is new to our

state, my comments have been

gleaned from conversations with

or reports from others that have

battled this pest in the mid Atlan-

tic states. Reports from those ar-

eas indicate that this insect be-

comes active in the field sometime

in mid to late April.

Brown marmorated stink bug has

been identified in several Ken-

tucky counties. It has been con-

firmed in Jefferson, Fayette, Boyd,

Carter, Rowan, Lawrence, and

Greenup counties and also re-

ported in Breckinridge, Grayson,

Henry, Carroll, and Lewis counties.

We have not seen specimens nor

been able to confirm the reports

from the last five counties listed.

This pest is a very capable hitch-

hiker and has the ability to rapidly

move to new areas. If you suspect

BMSB from a county that has not

yet been confirmed to have it,

bring a sample specimen to your

county extension office.

Damage to field crops has been

serious in soybeans and field corn

in the mid Atlantic states. In both

of these crops BMSB feeds on the

fruiting part of the plants, the de-

veloping soybean pod or the corn

ear. Pod feeding will result in dis-

colored and shriveled beans simi-

lar to that caused by other stink

bugs to soybeans. In field corn

they will feed through the husk

with their piercing sucking mouth-

parts causing shriveled kernels.

BMSB that are crushed during the

chopping of silage and fed to dairy

cattle may cause an off flavor in

milk (a cilantro-like flavor).

In vegetable crops, BMSB will

cause damage to tomato and pep-

per fruit similar to that of the

brown stink bugs. They feed on

developing fruit with the piercing

sucking mouthparts causing hard

corky areas under the skin of the

fruit that does not color properly.

Damage to sweet corn is similar to

that described for field corn, ex-

cept that damaged kernels will dis-

color when cooked. With green

beans, they attack the flowers and

pods resulting in deformed pods

and shriveled and/or missing

seeds. With squash and pumpkins

they are reported to attack the

fruit and even kill plants.

In fruit crops, particularly apples,

pears, peaches and nectarines,

BMSB is reported to begin attack-

ing developing fruit very early in

the season and continue through

harvest. For this reason, growers

are advised to monitor for BMSB

weekly from fruit set until harvest.

Damage to tree fruits will result in

sunken areas on the fruit surface

and discolored darkened, corky

areas under the skin of the fruit.

These depressions appear to be up

to 3/8 inch or so in size. These

damaged spots can easily be mis-

taken for cork spot on apples.

They will also feed on blueberries,

brambles, and strawberries, but I

Recognizing Brown Marmorated Stink Bug Damage

By Ric Bessin, Extension Entomologist, University of Kentucky

haven’t seen reports on the types

of damage. Damage by our brown

stink bugs in brambles can result

in undersized droplets and drop-

lets that don’t color properly. In

grapes they will attack the berry

and can also act as contaminant

causing an off flavor in wine if the

bugs are crushed with the berries.

It has been reported that as few as

10 per lug of grapes can create a

noticeable off-flavor. Figure 4. Brown marmorated stink bug

Winter Drying of Broad-

leaved Evergreen Trees and

Shrubs

By John Hartman, Extension Plant Pathologist,

University of Kentucky

Some County Extension Agents

and Landscape Professionals are

noticing that the leaves of broad-

leaved evergreens in the land-

scape are showing symptoms of

leaf margin browning. Affected

plants include cherry laurel, rho-

dodendron (Figure 5), and south-

ern magnolia (Figure 6). Although

the winter has been cold, plants

showing these symptoms are not

suffering from cold injury. The

damage is caused, rather, by desic-

cation.

Broadleaved and needled ever-

greens transpire water vapor in all

seasons although much less in

winter months. If roots are frozen

or the soil is dry from last fall’s

drought, the water loss through

the leaves might not be replaced

adequately and the leaf edges dry

out. Plants in sunny locations or

exposed to dry winter winds are

most vulnerable.

Symptoms can also occur on nee-

dle evergreens with browning af-

fecting whole needles or progress-

ing from the needle tips. In some

broadleaved evergreens, infec-

tious disease on the leaf edges

(Figure 7) can be mistaken for win-

ter drying or may compound the

effects of winter drying.

Figure 5. Winter drying

has desiccated this rho-

dodendron leaf. APS

Photo.

Figure 6. These mag-

nolia leaves show

typical winter drying

symptoms. C. Kaiser

photo.

Figure 7. Rhododendron leaves infected with Botryosphaeria

blight. This and other fungal pathogens such as the Pestalotia

blight fungus can also cause symptoms resembling winter drying.

In some cases, where winter drying has occurred, these secondary

fungi may develop on already dead leaf tissue. C. Kaiser photo.

Page 7 Inspector Findings in Kentucky

Periodical Cicada Emergence

in West Kentucky

By Lee Townsend Extension Entomologist,

University of Kentucky

Periodical cicadas that make up

Brood XIX soon will be leaving the

quiet life they have been leading

underground as sap feeders on

tree roots. After for 13 years in

the dark, nymphs will crawl up

vertical surfaces and molt to loud

(males), active adults (both sexes)

that will buzz around clumsily for

about 6 weeks.

These insects differ from the dog

day cicadas that we see near the

end of every summer. They are

smaller and have red eyes and red

-orange wing veins; these struc-

tures on the larger dog day cica-

das are green. Erratic fliers, cica-

das often stay in the upper can-

opy of trees where they are active

from late April through June. En-

counters with periodical cicadas

can be unnerving but these in-

sects cannot sting and do not

harm humans, livestock, or pets.

Except for the occasional dog or

cat that will suffer an upset stom-

ach from eating too many.

The estimated time table for

Brood XIX:

Emergence begins late April or

early May . Most out by late May.

Males begin to call females for

mating

Egg laying will begin in mid-May .

Last adults will disappear around

mid-June. Brood XIX will be active

in western Kentucky and parts of

Alabama, Arkansas, Georgia, Indi-

ana, Illinois, Louisiana, Maryland,

Missouri, Mississippi, North Caro-

lina, Oklahoma, South Carolina,

and Tennessee.

Please send observations and pic-

tures of the brood to

Lee.Townsend@uky.edu. Exam-

ples of useful information include

your location, date you first noted

emergence, estimated abundance

(light moderate heavy), date

males started singing, egg-laying

beginning, or other things you

find interesting. This information

will be posted at http://

pest.ca.uky.edu/EXT/Cicada/

kycic2011.html

Figure 8. Counties where periodical cicadas were active in 1998.

Page 8 Volume XV, Issue III

State Entomologist - John Obrycki, Ph.D

Joe Collins: Emerald Ash Borer Coordinator,

pest surveys & nursery licenses

Carl Harper: Slow-the-Spread gypsy moth

trapping coordinator, web design &

phytosanitary certificates

Katie Kittrell: EAB compliance inspections,

pest surveys, nursery inspections, newsletter

Janet Lensing, PhD: State Survey Coordinator

Jennie Condra: nursery inspections, pest

surveys

Phone: (859) 257-5838 Fax: (859) 257-3807

Email: joe.collins@uky.edu

carl.harper@uky.edu

katie.kittrell@uky.edu

janet.lensing@uky.edu

University of Kentucky

Department of Entomology

Office of the State Entomologist

S-225 Ag Science Ctr—N

Lexington, KY 40546-0091

Address service requested

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