kentucky pest news june 19, 2012
TRANSCRIPT
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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
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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