Kentucky Pest News June 29, 2010

8/9/2019 Kentucky Pest News June 29, 2010

1/6

Online at:www.uky.edu/KPN

Number 1236 June 29, 2010

WATCH FOR

-Armyworm Population Continues to Increase in

Central KY

CORN

-Southern Corn Rust is Moving North

SOYBEAN

-Japanese Beetles Feeding on Soybean

TOBACCO

-Tobacco Flea Beetles Still a Threat If NotManaged

WATCH FOR

VEGETABLES

-Squash Bug Eggs Out and Hatching

SHADE TREES & ORNAMENTALS

-Austrian Pine Diplodia Tip Blight

BUGS OF SUMMER-Hercules Beetles Defy Gravity

PESTS OF HUMANS

-Dipping Is Best Management Alternative for

Many Swimming Pool Insects

DIAGNOSTIC LAB HIGHLIGHTS

INSECT TRAP COUNTS

Armyworm Population Continues to Increase in

Central KYBy Doug Johnson

Capture of armyworm moths in the UK-IPM trapscontinues to increase in central KY. Trap captures

have more than doubled since last week, andcontinue to follow the trend establish by the 2008

population that resulted in damage. Pasture and hay

are the likely targets of the caterpillars that will

result from this population.

CORN

Southern Corn Rust is Moving North

By Paul Vincelli

Last weeks Kentucky Pest News included an article

about two rust diseases of corn, common rust and

southern rust. As described last week, southern rust

can be a significant problem if it attacks a corn crop

well in advance of maturity, because of its

aggressive nature and the susceptibility of many

hybrids.

A little more than a week ago, southern rust was

reported only in Georgia and in southern Alabama

(Figure 1). Since then, records of its occurrence

have been posted for northern Mississippi andnortheastern Arkansas, as well as new counties in

Alabama (Figure 2). I have also received industry

reports that the fungus has been found on corn east

of Memphis, TN, although we are waiting to learn

if that has been confirmed in the laboratory.

The rapid increase in reports of southern rust in just

eight days may be due in part to long-distance

dispersal of the fungus in weather systems.However, some of these new finds may simply be

documentation of infestations that established

earlier at very, very low levels and had escapeddetection because no one was looking for them

previously. In any case, the disease is likelyspreading and may pose a risk to some Kentucky

corn crops, especially late-planted ones. The

geographic progress of the disease can be

monitored athttp://sba.ipmpipe.org/cgi-

bin/sbr/public.cgi?host=Corn&pest=southern_corn_

rust.

Lexington, KY 40546
http://www.uky.edu/KPNhttp://www.uky.edu/KPNhttp://www.uky.edu/KPNhttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://sba.ipmpipe.org/cgi-bin/sbr/public.cgi?host=Corn&pest=southern_corn_rusthttp://www.uky.edu/KPN


2/6

SOYBEAN

Japanese Beetle Feeding on Soybean

By Doug Johnson

Japanese beetles are currently feeding across the

state on a variety of plants. Damage to soybean, one

of their target hosts, often prompts questions about

treatment. Fortunately, soybean can tolerate a great

deal of defoliation without a reduction in yield

potential. Yet, damage can be so visually stark (See

photo) as to cause many to question whether or not

a treatment is needed.

Generally speaking, the decision of whether or not

to treat soybean for a Japanese beetle infestation is

based on the defoliation rate, not the number of

beetles present. Nevertheless if the defoliation rate

is great enough to warrant control, rest assured that

there will be many, many beetles present.

Defoliation levels for making a treatment decision

may be found in Table 2. IN the InsecticideRecommendations for Soybeans 1010 which

may be obtained from your county extension office

or on line at:http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html.

Japanese beetle populations and their resulting

damage tend to be clumped. This can arise for many

reasons but is often associated with field edges,

waterways and other areas that contain permanent

stands of grass. Japanese beetles are grass loving

insect in that they lay their eggs in, and the resulting

Figure 1. Known distribution of southern corn rust in the

continental U.S. as of Sunday, June 20, 2010. Confirmed records

are indicated in red.

Figure 2. Known distribution of southern corn rust in thecontinental U.S. as of Monday, June 28, 2010.

Figure 3. Japanese beetle and their damage on

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


3/6

white grubs develop in, standing grasses. Be surethat your evaluation of the situation is not

prejudiced by only looking at border areas.

Japanese beetle is relatively easy to control. The

above publication contains a listing of insecticideslabeled for use against this pest on soybean. The

really important economic decision is whether ornot you NEED to control the pest.

TOBACCO

Tobacco Flea Beetles Still a Threat If Not

ManagedBy Lee Townsend

Most transplant insecticide applications for tobacco

provide excellent control of tobacco flea beetles forthe first 3

to 4

weeks

that the

crop is in

the field.

After

several

years of

using

these

treatments,it is easy to forget what can happen if preventive

control is not used and the crop is not checked for

damage for some time. Tobacco flea beetles hit this

crop severely in several areas of a field causing

substantial damage before the infestation was

detected.

Watch for budworm and tobacco hornworm

infestations, especially in the earliest set fields.

These are the ones generally selected by female

moths for egg laying. Both species spend the winter

deep in the ground as pupae so they are not affectedby the severity of winter weather and survival often

is good. There are many options for worm control

on tobacco but infestations need to be caught early

for best results.

Check randomly-selected plants scattered over the

field. Budworms will be in the tops of plant,

chewing small round holes in leaves and leaving

coarse pepper-like droppings. An average of 5 liveworms per 50 plants is enough to justify control.

Avoid treating when high temperatures cause upper

leaves to curl to protect plant buds, and the feeding

budworms. The same 5 live worms per 50 plants isused for determining the need for hornworm

treatments. These caterpillars will be found in theupper third of the plant.

VEGETABLES

Squash Bug Eggs Out and HatchingBy Lee Townsend

The squash bug can attack all of the cucurbit crops

but shows a preference for squashes and pumpkins.

This insect can be very difficult to control whenpopulations are allowed to build.

Squash bugs damage plants by removing sap and

causing leaves to wilt and collapse. Young plants

and infested

leaves on older

plants may be

killed. More

importantly,

they are the

vector of a

newlyrecognized

disease of

cucurbit crops,

Yellow Vine

Decline. Melons, watermelon, and pumpkins are

susceptible to this disease. The bacteria that causes

this disease is injected into the plant while squash

bug feeds with piercing-sucking mouthparts. The

disease results in yellowing, wilting and death of

the plant. Early infection by the bacteria that causes

the disease can result in severe yield loss, so it is

very important to prevent squash bugs from feedingon young plants early in the season. See more

information at

www.ca.uky.edu/entomology/entfacts/ef314.asp.

Figure 4. Severe tobacco flea beetle damage.

Figure 5. Squash bug egg mass and

newly hatched bugs.
http://www.ca.uky.edu/entomology/entfacts/ef314.asphttp://www.ca.uky.edu/entomology/entfacts/ef314.asphttp://www.ca.uky.edu/entomology/entfacts/ef314.asp


4/6

SHADE TREES & ORNAMENTALS

Austrian Pine Diplodia Tip Blight

By John Hartman

Austrian pines (Pinus nigra) are often planted in

Kentucky landscapes because of their dense, greenfoliage and symmetrical shape. When healthy, a

grouping of these trees can form an attractive year-

round screen. Diplodia tip blight symptoms have

become apparent during recent weeks on many

landscape Austrian pines. This disease, caused bythe fungusDiplodia pinea, is also known as pine tip

blight or Sphaeropsis tip blight, and is especially

devastating here in Kentucky on Austrian and Scots

pines. Over the past nearly two decades, we havebeen surveying and studying the damage this

disease has done to the Austrian pines on campus.

Symptoms. Tip blight symptoms first appear on

individual needles in the newly elongating candles

(shoots) in

late April to

early May

(Figure 6).

Other

needles in

the candleare killed

very

quickly and

by late Maythe diseased

shoot tips are noticeably necrotic and stunted

(Figure 7). Needles in dead shoot tips take on a

straw brown color and droplets of resin can

sometimes be seen exuding from these deadneedles.

Eventually

the stuntedcandle will

becomenecrotic

and brittle

from resin

exudationand turn a

gray color.

Later in the year as the fungus progresses from the

shoot tip back towards the branch, older needles

will become straw

colored and die.Over the years,

disease progressioncan lead to branch

dieback and

eventually death ofmany limbs on the

tree (Figure 8).

These symptoms

typically start in

lower branches of

the tree and

progress toward

higher branches

year after yearuntil the tree dies

or is so damaged it

needs to be

removed. On

landscape Austrian

pines in Kentucky, first disease symptoms generally

begin to appear after trees reach cone-bearing age,

typically 12-13 years old.

During recent decades, tip blight has caused heavy

losses to Austrian pines on the University of

Kentucky campus and in landscapes throughout theregion. The fungus is especially aggressive when

pines are growing under stressful conditions. Theperiodic summer droughts that are a part of

Kentucky climatology undoubtedly contribute to

periodic upsurges in disease incidence and severity.

Research done by Jen Flowers, a former graduate

student here, clearly showed that even healthy-appearing shoots and branches harbor latent

infections of theDiplodia fungus. These latent

infections appear to be held in check by tree

defenses which might be broken down when the

tree is subjected to stressful growing conditions.

Diplodia tip blight disease is very difficult to

manage.

Consider using native pines such as whitepine or Virginia pine in the landscape. Be

aware that in some parts of Kentucky white

pines have other kinds of problems such as

Figure 6. Diplodia tip blight showing early

browning symptoms on individual needles

in a candle.

Figure 7. Three Austrian pine shoot tips

turned brown due to Diplodia tip blight.

Figure 8. Austrian pine severely

affected by Diplodia tip blight

disease.


5/6

white pine decline and white pine rootdecline.

Provide landscape pines with adequatewater, especially during periods of drought.

Mulch trees to reduce soil water loss. Prune out infected shoots and branches and

remove old pine cones which may besources of inoculum. Avoid pruning trees

while they are wet.

Fungicides: In our experience, injections ofpines with systemic fungicides has had little

effect on tip blight and spraying pines with

fungicides may only slow the disease down

slightly. Spraying is often ineffective

because obtaining thorough coverage of the

tree is difficult.

BUGS OF SUMMER

Hercules Beetles Defy GravityBy Lee Townsend

The first Hercules

beetle of the year

arrived today.

This impressive

creature is 2" to

2-1/2" long witha greenish-gray to

black body.

Males have a

large distinctive

horn on the head;females do not. The adults are attracted to lights

during mid- to late summer and will eat overripe

fruit.

Hercules beetle larvae are white grubs that feed on

decaying plant material, especially logs, stumps,

dead leaves, and rotten fruit. They may spend two

years in this stage. The grubs are a food source for

skunks, raccoons, and other mammals.

PESTS OF HUMANS

Dipping Is Best Management Alternative forMany Swimming Pool InsectsBy Lee Townsend

Swimming pools attract a variety of insects. Theoccasional clumsy pool invaders are the easiest to

handle the few that fall in can be removed with a

cleaning net or cup.

Some are more numerous and persistent. Honey

bees come to collect water for use in their colonies.

A few aquatic insects, mostly bugs and beetles,

come because water is their natural environment; tothem, a swimming pool is just another pond. Thrips

come as a result of disturbances cutting hay fields

or wheat. Finally, there are those that just

accidentally fall into the water and cannot escape.

Honey bees (and wasps) need lots of water to

maintain optimum temperature and humidity; a

nearby swimming pool may be the most convenient

supply, causing alarm to pool owners and users.

Worker bees that find a good water source will

recruit colony mates to join them. Over time,

hundreds of bees may appear. Some will fall into

the water and drown but others will keep coming.

They are preoccupied with this task and generally

are not a threat. Dealing with bee visits to small

kiddy pools can be as simple as moving the pool toa different spot in the yard every few days. Bees

follow directions very strictly and if the pool is not

where it should be, they will not find it easily. You

can stay ahead of them with the moves.Figure 9. Female Hercules beetle.

Figure 10. Backswimmer - an

aquatic predator that hangs

upside down from the water

surface. The long back legs

work like oars to propel it

through the water.

Figure 11. Giant water bug - the

biter- can give a painful bite wit

its short, stout sucking mouthpa


6/6

Aquatic insects, such as backswimmer bugs and toe

biters, may arrive in large numbers as they fly from

ponds in which they developed to colonize other

bodies of standing water. In some cases, they may

be abundant enough to clog filtering systems.Usually, this mass movement lasts only a few days.

Backswimmers are predators; they can give apainful bite with their piercing-sucking mouthparts.

There should be no question as to what the toe biter

can do. The pain from these bites is similar to a beesting but there is no toxin.

Thrips can make a dramatic appearance. These tiny

elongate yellow insects were described on one

insect ID form as follows: "These little biting things

covered an aboveground pool and deck. They were

so thick that you could wipe them off with your

hand. They have painful bites, children could not

play in the pool for them."

Thrips show up at pools probably drawn to water or

driven there from nearby recently-cut hay fields. On

normal days thrips use their abrasive mouthparts to

rasp at plant tissue, especially flowers. However,

they will scrape skin, perhaps as they attempt to

pick up small amounts of moisture. An occasional

thrips scrape probably is tolerable but lots of them

do not add to the swimming experience. A strong

jet of water may be used to plaster them to decks

and other surfaces where they have accumulated.

Finding and managing the source of an insectproblem usually is the most effective management

practice but this is rarely possible or practical withswimming pool invaders. There is no safe or

effective means of treating pool water to keep

intentional or accidental invaders away. Covering

the pool when it is not in use may be the best and

only way to exclude chronic problems withunwanted creatures. Fortunately, this may be

needed for only a few days at a time.

DIAGNOSTIC LAB HIGHLIGHTSBy Julie Beale and Paul Bachi

Recent agronomic samples in the PDDL have

included low soil pH problems and nutritional

disorders including nitrogen, magnesium and zinc

deficiencies on corn; potassium deficiency on

soybean; black shank, Rhizoctonia stem rot,

temporary phosphorus deficiency, transplant shock,target spot, tomato spotted wilt virus and alfalfa

mosaic virus on tobacco.

On fruit and vegetable samples, we have diagnosedanthracnose on grape; cane blight on blackberry;

Phytophthora crown rot on strawberry; brown roton plum; fire blight and cedar-apple rust on apple;

scab and Oriental fruit moth injury on peach;

anthracnose, southern blight and Rhizoctoniaroot/stem rot on bean; stinkbug injury on sweet

corn; sour skin, pink root (Phoma) and purple

blotch (Alternaria) on onion; Pythium fruit rot,

bacterial spot and southern blight on pepper;

bacterial wilt on squash and muskmelon; early

blight on potato; bacterial spot/speck, early blight,

southern blight, Pythium fruit rot, Fusarium wilt,

walnut wilt, Septoria leaf spot and blossom end rot

on tomato.

On ornamentals and turf, we have seen rust on

hollyhock; Pythium root rot and Rhizoctonia

root/stem rot on petunia; leaf streak on daylily;

black root rot on holly; Botrytis blight on rose;

bacterial leaf spot on ornamental cherry;

Phloeosopra leaf spot on mulberry; Rhizosphaera

needlecast and Stigmina needle blight on spruce;

Verticillium wilt on catalpa and tuliptree; Diplodia

tip blight and Dothistroma needle blight on pine;

black layer and take-all patch on bentgrass;

Pythium blight on perennial ryegrass; and brownpatch on fescue.

INSECT TRAP COUNTSJune 18-25

Graphs of insect trap counts for the 2010 season are available on theIPM 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

Location Princeton,

KY

Lexington,

KY

Black cutworm 34 16

Armyworm 2 821

Corn earworm 22 29

European corn

borer

3 3

Southwestern

corn borer

0 0

Fall armyworm 42 0

Documents

Kentucky Pest News June 29, 2010