kentucky pest news june 19, 2012

7/31/2019 Kentucky Pest News June 19, 2012

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Online at:www.uky.edu/KPN

Number 1307 June 19, 2012

CORN

-Watch for Japanese Beetle on Silking Corn

CUCURBITS-Pollination of Cucurbits

VEGETABLES

-Bacterial Fruit Blotch Found on Watermelon

FRUIT CROPS

-Black Rot of Grape

CORN

Watch for Japanese Beetle on Silking CornBy Doug Johnson

Japanese beetles have been emerging over the last

couple of weeks. With the general rainfall we had

last Monday (6/11/12) this emergence is likely to

quicken. While this insect will feed on corn leaves,its only real importance is when feeding on

emerging silks. This silk feeding can interfere with

pollination resulting in incomplete kernel set.

Figure 1. Japanese feeding on corn silks.

ORNAMENTALS & SHADE TREES

-Impatiens Downy Mildew

-Woolly Aphids

LIVESTOCK

-Darkling/Mealworm Beetles in Hay or Feed

HOUSEHOLD PESTS

-Fishing Spider/Nursery Web Spider

DIAGNOSTIC LAB HIGHLIGHTS

INSECT TRAP COUNTS

These insects are metallic green beetles about

long. They have a row of white tufts on either side

of the body below the bronze wing covers. The

beetles will congregate (sometimes in very large

numbers) on ear tips and feed on the silks, thus

preventing proper pollination.

Normally, this insect is not a major pest of corn.However, in this year because of the mild winter

and very warm spring the pest is emerging at an

earlier date. Also, because of the dry soil

conditions in the western part of the state, the

emergence which is normally spread out in time,

may occur over a much shorter time period

producing an unusually large number of beetles

seemingly all at once.

Scout for this insect by examining severalindividual groups of 20 consecutive ears.

Determine if the silks have been clipped to within

1/2 in length. Additionally, count the number of

beetles per ear and average these numbers for the

twenty ears per sample, then average all thesamples taken in the field. Treatment may be

necessary if silks have been clipped to and

there are three or more beetles per ear.

Lexington, KY 40546
http://www.uky.edu/KPNhttp://www.uky.edu/KPNhttp://www.uky.edu/KPNhttp://www.uky.edu/KPN


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If pesticide application becomes necessary,

pesticides useful for control of Japanese beetle can

be found in ENT-16, Insecticide

Recommendations for Corn-2012, which may be

obtained from your County Extension Office or online at:

http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html

Photo: D. Johnson, Univ. KY

CUCURBITS

Pollination of Cucurbits

By Ric Bessin

There has been considerable concern over the loss

in numbers of honey bees over the past 6 years and

some cucurbit growers have expressed concern

over the lack of pollinators. Cucurbits are entirely

dependent on insect pollinations, it is simple: No

insect pollinators, no fruit. Honey bees are

fantastic as pollinators of these crops as they are

so easily manipulated by moving in colonies as

needed. In the absence of pollinator activity,

honey bee colonies can be moved in quickly to

provide necessary pollination services typically atthe rate of one or two colonies per acre. With

vegetable farms in Kentucky, many growers have

been able to rely on wild honey bees moving from

surrounding areas to pollinate smaller acreages,but concern has been increasing with the recent

losses.

Figure 2. Honey bees are relatively easy to manipulate for

pollination.

There are several important wild bee pollinators of

cucurbits, and to some extent the cast of

pollinators depends on the type of cucurbit

species. Basically there are two types of cucurbit

flowers; the small melon, watermelon andcucumber flowers, and the larger squash and

pumpkin flowers. Logan Miner, PhD student in

Entomology, has been conducting surveys of

pollinators in squash and melon fields the pastthree years. Heres what he has found through

surveying commercial farms.

Bumble bees: Several species are very common toboth melons and squashes in Kentucky, but

Bombus impatiens appears to be the most

common. Bumble bees are common early in the

day often before honey bees are foraging. Bumblebees are considered very effective pollinators ofcucurbirts.

Figure 3. Bombus impatiens is a common pollinator of both

squash and melon flowers.

Squash bee: The squash bee is a specialist for

squash flowers and pollinates little else

(sometimes found pollinating morning glory).

Squash bees do not pollinate melon flowers.

Squash bees are very common and build

individual nests in bare or nearly bear ground.

The squash bee looks similar to honey bees, but is

a bit larger , hairier, with more colored banding
http://pest.ca.uky.edu/EXT/Recs/welcomerecs.htmlhttp://pest.ca.uky.edu/EXT/Recs/welcomerecs.htmlhttp://pest.ca.uky.edu/EXT/Recs/welcomerecs.htmlhttp://pest.ca.uky.edu/EXT/Recs/welcomerecs.htmlhttp://pest.ca.uky.edu/EXT/Recs/welcomerecs.html


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of the abdomen. Squash bees are often the first

pollinators to begin in the morning often working

flowers before sunrise. Early in the summer, males

and female squash bees can be found sleeping in

wilted squash flowers from early afternoon untilthe next morning.

Figure 4. The squash bee in often the earliest first to begin

pollinating in the morning.

Long-horned bees (Melissodes bimaculata): ThisMelissodes species is about the same size as a

honey bee, almost black in color with a pair of

light colored marking on the abdomen and lightcolored hairs on the hind legs. These ground-

nesting bees fly very quickly between flowers and

do not spend much time in any one flower. Logan

Minter has observed them going under the plastic

mulch to nest and can be common in squash fields.

Sweat bees (Agapostemon spp. And Lasioglossum

spp.): Smallish black and metallic green bees.

There are many species and distinguishing themcan be impractical. As a group these may be the

most common group of pollinators, but there

contribution to adequate on a per visit basis may

be considerably less than that the pollinators listed

above. While they may lack the efficiency of thelarger pollinators, they can be frequent flower

visitors.

Generally, when female flowers begin to open,

those are the flowers that have a tiny fruit just

below the flower, growers should monitor foradequate pollination activity. On a warm sunny

day with little wind, pollinators should be common

in the planting by mid-morning. If pollinators are

lacking, growers may need to contact a localbeekeeper to move bees near the field. Misshapenor fruit failing to size are often indicators of poor

pollination.

VEGETABLES

Bacterial Fruit Blotch Found on WatermelonBy Kenny Seebold

Bacterial fruit blotch was confirmed recently

greenhouse-grown transplants of seedless

watermelon (Utopia), and also Athena

cantaloupe. We also found active disease on

plants in the field that had come from the

greenhouses in question. The first-ever case of

this disease in Kentucky was reported last year and

caused a significant amount of damage to one

growers field. The pathogen,Acidovorax avenaesubsp. citrulli, is a bacterium that is spread mainly

on seed. The disease can affect most cucurbits;

however, watermelon tends to be most susceptible.

Symptoms of bacterial fruit blotch often appear

first on seedlings in greenhouses as water-soaked

areas on the undersides of cotyledons (Fig. 5).

These lesions eventually turn necrotic and take on

a reddish-brown color, extending along the midrib

of affected cotyledons (Fig. 6). The pathogen iseasily spread in greenhouse environments by

physical contact or water splash, and symptoms

can develop on true leaves. When infected plantsare set in the field, secondary infections can occur

during warm, rainy periods. Symptoms appear asnecrotic, angular areas (Fig. 7); foliar symptoms in

the field may be difficult to see, particularly as

canopy density increases. During fruit set,

bacteria can be spread from foliar lesions (or

infected melons) to developing fruit following


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rain, irrigation, or mechanical contact. Fruit are

most susceptible to infection during the first 2-3

weeks of development; after this period, a waxy

layer is present on the rinds of fruit that

significantly reduces the ability of the pathogen toinfect. Symptoms on fruit appear first as water-

soaked, darkened areas on the upper portions ofmelons (Fig. 8). These areas expand, and the rind

can eventually crack. Liquid or foam can be

expelled from cracked areas during hot weather

(Fig. 9).

For the moment, we have observed bacterial fruit

blotch mainly on Utopia watermelons, and

growers with this variety should scout greenhouses

and fields for symptoms of this disease. Control

of bacterial fruit blotch can be difficult under

disease-favorable conditions (warm and wet

weather). If the disease is found in thegreenhouse, all seedlings should be destroyed to

prevent introduction of the pathogen into the field.

If infected seedlings are set in the field, or if the

disease is observed on newly-set plants, weekly

applications of copper fungicide are

recommended. Sprays should continue until 3-4

weeks after fruit set. Rotate away from fields

affected by fruit blotch for 2-3 years and destroy

volunteer melons that may emerge.

Figure 5. Water-soaked areas on cotyledons of watermelon

seedlings infected by the bacterial fruit blotch pathogen.

Figure 6. Older lesions of bacterial fruit blotch on

watermelon seedlings.

Figure 7. Symptoms of bacterial fruit blotch on leaves of

newly-transplanted watermelons.

Figure 8. Early symptoms of bacterial fruit blotch on

watermelon rinds.


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Figure 9. Cracking and ooze associated with bacterial fruit

blotch.

FRUIT CROPS

Black Rot of GrapeBy Nicole Ward

Black rot is the most common disease of grape in

Kentucky. If left unprotected, vineyards can

suffer high economic losses.

Infection occurs early in the season, usually before

bloom, at temperatures as low as 50F. Early

symptoms develop as spots on leaves 1 to 2 weeks

after infection (Fig 10). Tan spots with darker

margins often contain black fruiting structures

(pycnidia) in centers (Fig.11). Spores (conidia)

from these structures cause secondary infections

throughout the season. As leaves mature, they

become resistant, but newly developing leaves can

become infected anytime during the season.

Fruit infections occur early in the spring, as well.

Grapes are susceptible from flowering until 3 to 4

weeks after bloom. Early fruit symptoms appear

as light brown spots (Fig. 12). Soon, entire berries

turn dark brown and shrivel (Fig 13). These

raisin-like fruit develop black fruiting structures

(pycnidia) that overwinter on the mummies.

Both cultural practices and fungicides are critical

for control of black rot. Fruit mummies must be

removed from vineyards to eliminate sources ofoverwintering inoculum. Beginning at pre-bloom,

a rigid fungicide regime must be employed.

Strobilurin fungicides (Abound, Pristine, Flint)

provide excellent control, but risk for fungicideresistance is high. Rotate with triazole/SIfungicides (Bayleton, Elite, Rally) and protectant

fungicides (Mancozeb, Ziram).

Commercial growers should refer to the Midwest

Small Fruit and Grape spray guide for fungicide

and schedule details, while homeowners can use

fungicides listed in ID-21 and PPFS-misc-7.

These and other publications can be found at

http://www.ca.uky.edu/agcollege/plantpathology/e

xtension/pubs.html#Smallfruit

Figure 10. Leaf lesions have light tan centers and darker

brown margins.

Figure 11. Fruiting structures (Pycnidia) produce spores that

cause secondary infections. They can be seen with a

magnifying glass, and often with the naked eye.
http://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruithttp://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruithttp://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruithttp://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruithttp://www.ca.uky.edu/agcollege/plantpathology/extension/pubs.html#Smallfruit


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Figure 12. Fruit infections begin as light brown spots. Note:

bird's eye rot (anthracnose) infections on fruit have dark

reddish margins with light gray centers.

Figure 13. Soon after infection, grapes with black rot

disease turn dark and shrivel into hard, black mummies.

Fruiting bodies (pycnidia) that develop are the primary

source of overwintering for this fungus.

ORNAMENTALS & SHADE TREES

Impatiens Downy MildewBy Nicole Ward

Downy mildew of impatiens caused quite a stir inthe region last year. Luckily, we did not see this

devastating disease in Kentucky. Last week, the

pathogen was identified in multiple landscapes in

North Carolina, so our risk for detection here in

Kentucky is high.

Downy mildew of impatiens is caused by the

water mold Plasmopara obducens. Like other

downy mildew pathogens, this organism favorscool, wet/humid conditions. Although it has been

quite dry in the region, impatiens downy mildew

can originate in propagation greenhouses, and then

thrive in irrigated landscapes and retail nurseries.Once established, the pathogen is spread by windcurrents, water splash, and by movement of

infected plants.

Most types of impatiens (Impatiens walleriana,

including double impatiens and mini-impatiens,and anyI. walleriana interspecific hybrids, such as

Fusion impatiens) are susceptible to downy

mildew. However, New Guinea impatiens (I.

hawkeri) and interspecific hybrids such as

SunPatiens are tolerantto the disease.

Fungicides are not recommended for management

of impatiens downy mildew, as inconsistencies

have been reported. Remove all infected plants,

and destroy by burying or burning. Contact N.

Ward or the UK Plant Disease Diagnostic

Laboratory if you suspect impatiens downy

mildew in your nursery or landscape.

Figure 14. Infected leaves may include classic downy

mildew symptoms - white-colored fungal growth and

sporulation. If conditions are hot or dry, sporulation may

not be visible (K. Ivors).


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Figure 15. Chlorosis is often the earliest symptom of downy

mildew of impatiens. Leaves may curl downward, giving

plants a wilted appearance (M. Daughtrey).

Woolly AphidsBy Lee Townsend

Woolly aphids are group of sap-feeding insectsthat produce white filaments resembling strands of

cotton or wool. The woolly alder aphid has been

especially abundant this year and may become

more so as wool-streaming adults drift through the

air in hopes of finding their alternative hosts. Youmay have seen this one or other species this

spring.

Figure 16. Waxy filaments of woolly aphids.

Woolly alder aphids are sap feeders that split their

life cycle between silver maple and alder. Thin

strands of white woolly wax develop as the aphidsfeed and grow. Infested leaves may curl or pucker

but healthy established trees are rarely harmed.

These aphids produce sugar-rich liquid waste

(honeydew) that drips onto foliage and branches

below them attracting bees, wasps, and flies. Sooty

mold fungus can grow on the honeydew deposits,

blackening leaves and branches and making

objects below sticky.

Wooly alder aphids can be a nuisance but usually

do not damage healthy, established silver maples.

Also, they leave them for alder by about mid-June

so control is not needed. After arriving on alder,

the aphids will settle and feed during the summer

months, also producing wool. Some will remain

on alder during the winter. A few male and female

aphids will return to maple and mate. Each female

will lay a single egg in a bark crack or crevice

which will remain there over the winter. The eggs

will hatch in the spring and repeat the life cycle.

LIVESTOCK

Darkling/Mealworm Beetles in Hay or FeedBy Lee Townsend

Finding beetles in stored alfalfa hay or animal feedraises an immediate red flag. Are they blister

beetles? If not, what are they and are they

harmful? Usually, it is darkling beetles, they

larvae are called mealworms. These insects tend to

hide so they can be found under, in, or between

stacked hay bales. Darkling beetles do not contain

cantharidin, the toxin in blister beetles, they are

not harmful.

Darkling beetles are different from blister beetles.

The most obvious feature is the distinctly narrow

neck of a blister beetle which lies between thehead and thorax of the insect. In contrast, the

neck area of the darkling beetle is wider than its

head. Also, they have hard front wings compared

to the soft, more flexible front wings of blister

beetles.


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Mealworms, the larval stage of the darkling beetle,

are common in stored or spilled grain or feed,

where they eat broken kernels and fines. Adults

often wander some distance from their breeding

site and enter stacked hay so it can be hard to findthe source of the infestation.

Sanitation is the key to dealing with darkling

beetles but it can be difficult to find and eliminate

all breeding sites of these insects. Fortunately,

their development is relatively slow so it takes

time for large numbers to develop. Brooms and

shop vacs need to be used to clean all accessible

fines.

Infestations in stored bulk feed are more difficult

to address, depending on the amount that is

present, how quickly it will be used, and time of

year. It may be best to feed out the supply andthoroughly clean the storage area and surroundings

before re-filling it. A pyrethrin spray labeled for

use in feed storage areas after clean up will help to

eliminate surviving insects.

Information on blister beetles in alfalfa is available

in this factsheet -www.ca.uky.edu/entomology/entfacts/ef102.asp

Figure 17. Darkling/Mealworm beetle.

Figure 18. Blister beetle (left) with distinct "neck", the

darkling beetle (right) does not have a narrow neck.

Figure 19. Mealworm -darkling beetle larva.

HOUSEHOLD PESTS

Fishing Spider/Nursery Web SpiderBy Lee Townsend

Nursery web and fishing spiders are the largest

spiders you are likely to see in Kentucky. They are

active hunters that are very similar in appearanceand habits to the common wolf spiders that can be

seen running across the ground. They move about

searching for prey- insects, worms, spiders, and

other small creatures. These spiders generally only

come inside as accidental invaders but may remain

around damp, undisturbed areas of basements,

garages, and outbuildings.

In spite of their size and rapid movement, they are

neither aggressive nor dangerous. However, one

could give a painful bite if accidentally mashed or

threatened.

Reducing hiding places, such as tall grass and

clutter, around foundations will discourage these

spiders. It is also important to seal as many cracks

and crevices as possible to keep them from

wandering into structures. Placing sticky cards

(Mouse Glue Boards, Roach Motels) along

baseboards or undisturbed areas can capture
http://www.ca.uky.edu/entomology/entfacts/ef102.asphttp://www.ca.uky.edu/entomology/entfacts/ef102.asphttp://www.ca.uky.edu/entomology/entfacts/ef102.asp


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incidental wandering spiders and identify areas

that may need control measures.

Figure 20. Nursery web spider.

Pest-proofing lawns and play areasBy Lee Townsend

Summer means the opportunity for lots of outdoor

play time but also provides the opportunity for

bites and stings along with the normal scrapes and

bruises. Spiders, bees, and wasps are among the

backyard creatures that are commonly

encountered. Some education and regular

inspections of potential trouble spots will go a

long way toward reducing problems. A proactiveapproach and a watchful eye is needed with very

small children but providing some age-appropriate

information on recognizing common pests and

learning what to do to avoid problems is part of

developing outdoor readiness.

Here are some examples and countermeasures:

Chiggers and ticks live in areas with tallgrass and weeds. Keep grass mowed to

remove what chiggers and ticks need: high

humidity and protection from excess

sunlight. Spiders tend to remain around undisturbed

clutter, indoors and out. It gives them

protection and a place for their prey to

live. Removing clutter and regularly

disturbing what remains will make places

undesirable for spiders and their prey.

Spiders also can take up residence in tall

grass around the supports for swing sets

and other fixed playthings. These areas

should be clipped regularly. Outdoor toy

chests, gymsets, and playhouses should be

checked weekly look closely at corners

for signs of spiders and webs.

The warning coloration yellow, orange,and black markings on wasps and bees forexample - warns of the ability to sting or

bite. Usually, these insects are busy

collecting supplies for their nests and are

completely uninterested in humans. They

will only react if disturbed, captured, or

crushed. Learning to leave them alone and

moving slowly away is a good strategy.

Yellowjackets often nest below groundwith an opening near surface rocks,

landscape logs, or beneath shrubs. Some

social wasps and hornets nest in hollow

spaces in trees, toy chests, and similarplaces. Seeing them regularly fly to and

from a specific spot in the yard suggests a

nest. Avoid the area until the presence of a

nest can be confirmed and treated.

Accidentally approaching a wasp nest can

provoke a defensive response. It is better

to remain as motionless as possible. Angry

bees and wasps go toward movement. Try

to remain still and slowly back away from

danger rather than run while wildly

flailing arms.

Sweat bees and other insects often land onthe skin. Brushing them off is much better

than slapping them, which often results in

a sting.

Sweet drinks and food can attract bees andwasps, especially later in the summer.

Keep food and drink covered when

outdoors to minimize attraction. Clean up

sweet, sticky spills quickly to avoid

attracting many unwanted visitors.

Sand boxes, especially when usedinfrequently, provide the loose, well-

drained area that ground-nesting bees andwasps prefer. Thoroughly disturbing the

sand every couple of weeks should make

the area unsuitable for tunneling insects.

Regular inspections and cleaning candetect and remove many potential pest

problems. A broom and sprayer with

insecticidal soap is usually enough to
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dispense with most problems. However,

dealing with established wasps and

hornets is best left to professionals.

DIAGNOSTIC LAB HIGHLIGHTS

By Julie Beale and Paul Bachi

Agronomic samples during the past week included

zinc deficiency on corn; Lepto leaf spot on alfalfa;

Rhizoctonia root rot, Phytophthora root rot and

potassium deficiency on soybean; manganese

toxicity, temporary phosphorus deficiency,

sunscald, numerous cases of tomato spotted wiltvirus, black shank, Pythium root rot and Fusaruim

wilt on tobacco.

On fruit, vegetable and herb samples, we have

diagnosed iron deficiency on blueberry;

anthracnose, black rot and Phylloxera on grape;angular leaf spot on strawberry; fire blight, cedar-

apple rust and frogeye on apple; downy mildew on

basil; anthracnose and Rhizoctonia root/stem rot

on bean; bacterial wilt on cantaloupe and

cucumber; bacterial spot on pepper; scab on

potato; purple blotch (Alternaria) on onion;Rhizoctonia root/stem rot on okra; bacterial spot,

bacterial wilt, leaf mold, early blight, Septoria leaf

spot, Fusarium wilt, Phoma leaf spot, blossom end

rot, Pythium root rot and tomato spotted wilt viruson tomato; and bacterial fruit blotch on

watermelon.

On ornamentals and turf, we have seen Alternaria

leaf spot on aster; Phytophthora crown rot and

anthracnose on liriope; leaf blight (Insolibasidium)

on honeysuckle; cedar-quince rust on serviceberry;

Rhizosphaera needlecast on spruce; anthracnoseon bluegrass; and brown patch on fescue.

INSECT TRAP COUNTSJune 7 - 14

Graphs of insect trap counts for the 2012 season are availableon the IPM web site at -

http://www.uky.edu/Ag/IPM/ipm.htm.View trap counts for Fulton County, Kentucky at -http://ces.ca.uky.edu/fulton/InsectTraps

Note: Trade names are used to simplify the information

presented in this newsletter. No endorsement by the

Cooperative Extension Service is intended, nor is

criticism implied of similar products that are not

named.

Location Princeton,

KY

Lexington,

KY

Black cutworm 0 0

Armyworm 3 1Corn earworm 2 2

European corn

borer

0 0

Southwestern

corn borer

2 0

Fall armyworm 1 0
http://ces.ca.uky.edu/fulton/InsectTrapshttp://ces.ca.uky.edu/fulton/InsectTrapshttp://ces.ca.uky.edu/fulton/InsectTraps

kentucky pest news june 19, 2012

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