kentucky pest news april 27, 2010

8/9/2019 Kentucky Pest News April 27, 2010

1/13

Online at:www.uky.edu/KPN

Number 1227 April 27, 2010

SOYBEAN

-Late Burndown Control of Marestail in Full-

Season No-Till Soybeans

TOBACCO

-Update on Tobacco Float Bed Diseases

WHEAT

-New Tool for Assessing Fusarium Head Blight(Head Scab) and Deoxynivalenol (DON) Risk in

Wheat

FRUIT CROPS

-Leaf Wetness Promotes Apple and Grape

Infections

SOYBEAN

Late Burndown Control of Marestail in Full-

Season No-Till SoybeansBy Jim Martin and J.D. Green

Most of the marestail that occurs in Kentucky is

resistant or highly tolerant to glyphosate (see

young marestail on April 24, 2010 in Figure 1).

The use of 2,4-D as a tank mix partner with

glyphosate has been a standard option for

managing glyphosate-resistant marestail (also

known as horseweed) in full-season no-till

soybeans. One drawback with this option is that

it requires 7 to 30 days between application and

soybean planting. Another concern with 2,4-Dester is the risk of drift to nearby sensitive

plants.

Some alternatives to 2,4-D for burndown control

of marestail include: 1) products containing the

active ingredient saflufenacil or 2) Ignite. These

options do not require a delay in planting of

soybean and generally are not as great of risk of

SHADE TREES

-Winter Injury in the Landscape

-Emerald Ash Borer Trapping Begins

-Yellow Poplar Weevils

-Pine Bark Adelgid Snowy & Showy

LAWN & TURF

-Nematodes and Turfgrasses

PESTS OF HUMANS & ANIMALS

-Black Flies Attack People and Livestock

PESTICIDE NEWS & VIEWS

-Belay 2.13 SC Receives Expanded Use Labelfor Fruits and Vegetables

-Tourismo Labeled for Some Fruit Crops

DIAGNOSTIC LAB HIGHLIGHTS

injuring nearby tobacco or similar crops

compared with 2,4-D.

Products with saflufenacil

Sharpen (saflufenacil) and Optill (saflufenacil +

imazethapyr) are new burndown herbicides

labeled to control marestail up to 6 inches inheight. The maximum recommended rate for

use of Sharpen in soybean is 1 fluid oz/A;

whereas, Optill is recommended at 2 oz/A.

Although the labels of both Sharpen and Optill

recommend using methylated seed oil (MSO) or

crop oil concentrate (COC), there is increasing

evidence that MSO is preferred over COC formarestail control. The additional cost of using

MSO over COC is probably worth the

investment for managing this weed. In addition

to MSO the use of ammonium sulfate (AMS) or

liquid urea ammonium nitrate (UAN) is also

required with Sharpen or Optill.

Lexington, KY 40546
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Sharpen and Optill are somewhat narrow in the

spectrum of weeds controlled in burndown

treatments; consequently it is likely these

products will be tank mixed with glyphosate or

another herbicide. The current recommendedadjuvant system for tank mixing these products

with glyphosate is MSO plus AMS. MSO isnormally not recommended with glyphosate,

however, there is mounting evidence that

indicates MSO is superior to nonionic surfactantfor marestail control when tank mixing Sharpen

or Optill with glyphosate.

The labels for Sharpen and Optill recommend

against tankmixing or using sequential

applications within 30 days of other PPO

inhibitors such as sulfentrazone (e.g. Authority

products) or flumioxazin (e.g. Valor products),

due to the risk of crop injury. The interaction ofthese herbicides may also impact marestail

control. Recent research at University of

Tennessee indicates that tank mixing Sharpen

with Valor limited Sharpens ability to control

emerged marestail plants.

Ignite 280 SL

The use of Ignite 280 SL at 29 oz/A is labeled to

control marestail 6 to 12 inches in height.

Thorough spray coverage is important for

marestail control with Ignite, therefore

treatments need to be applied in a minimum of15 gallons of water per acre. In order to achieve

optimum marestail control, weather conditionsneed to be favorable for plant growth. Warm

temperatures, high humidity, and bright sunlight

enhance the weed control with Ignite.

While Ignite is usually effective on managing

marestail, there may be few instances wherelarge plants are not completely controlled. If

growers commit to using Ignite as a burndown

option, then Ignite should not be used

postemergence in crop on Liberty Link

soybean, due to label restrictions.

TOBACCO

Update on Tobacco Float Bed DiseasesBy Kenny Seebold

Above-normal temperatures have prevailed from

the end of March through the first two weeks ofApril, and weve been pretty dry as well. With

the increased heat, wed naturally worry a little

about Pythium becoming active on roots oftobacco, and the risk from bacterial soft rot

(black leg) would be elevated as well. The last

things that wed think would be a problem

would be target spot and collar rot, yet both

diseases are starting to crop up around variousparts of the state. The appearance of these

diseases more-or-less coincides with the passing

of a cold front around April 16, when we also

saw a little cloudy and rainy weather. With thecooler temperatures, and rain forecasted through

April 27, we should expect a fair number of

cases of target spot to crop up. An article on

managing target spot was published in the

Kentucky Pest News (No. 1225, April 13, 2010);

this weeks report will focus on the

identification and management of collar rot.

BACKGROUND. Collar rot shows up in float

beds in the spring, when resting structures

(sclerotia) located outside the float system

germinate produce cup-shaped fruiting bodiescalled apothecia. Apothecia then produce spores

(ascospores) that are dispersed on wind currents.

When ascospores land on susceptible tissue, they

germinate if sufficient moisture is present. Long

periods of leaf wetness (greater than 16 hours)

are required for this process. Germinated

ascospores produce hyphae (fungal threads)

that penetrate tissue and begin the infection

process.

SYMPTOMS. The first symptoms of collar rot

are small, dark green, water-soaked lesions thatappear at the bases of stems. In most cases, this

disease becomes apparent when clusters ofinfected transplants collapse, leaving open holes

in the plant canopy (Figure 2). These clusters,

or foci, are usually grapefruit-sized (4-6 in

diameter). Stems of affected seedlings generallyshow a wet necrosis that is amber-to-brown in

color, beginning at the base of the plant and

Figure 1. Young marestail.
http://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_10/pn_100413.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_10/pn_100413.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_10/pn_100413.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_10/pn_100413.html


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extending upward (Figure 3). Signs of the

causal agent, Sclerotinia sclerotiorum, may be

present on symptomatic plants or on debris in

float trays. These signs include a white, cottony

mycelium (fungal mass), present if humidity ishigh, and irregularly shaped, black sclerotia

(Figure 4). Sclerotia resemble seeds or rodentdroppings and are the primary survival structure

ofS. sclerotiorum and are the primary source of

inoculum for outbreaks in subsequent years.

Plants that are 5-7 weeks old are most

susceptible to collar rot. We often see the first

cases shortly after plants are first clipped

following a period of disease-favorable weather.

Cool temperatures (60 to 75 F), high humidity,

and overcast conditions, like those that have

been common in Kentucky for the past week, are

ideal for development of this disease. Its alsoimportant to note that S. sclerotiorum is an

efficient colonizer of dead plant matter and

weakened or injured tissue, and these are usually

the first to be attacked. The fungus will then

move from these areas to nearby healthy plants

as long as cool temperatures and high humidity

prevail. This is one of the ways that secondary

spread of the collar rot pathogen takes place,

since S. sclerotiorum does not produce airborne

spores on infected tissue. The other way in

which secondary spread can occur is through

dispersal of infected tissue a possible eventwhen infected plants are clipped.

MANAGEMENT. There are no fungicides

labeled for control of Sclerotinia collar rot on

tobacco transplants, making this a difficult

disease to manage. Sound management

practices are the only options that a grower canuse to fight collar rot. Adequate ventilation and

air circulation are a primary concerns, since

these limit the duration of leaf and stem wetness.

Growers should manage temperatures to

promote healthy plants and minimize injury.The latter is important because injured tissues

are more susceptible to S. sclerotiorum. Fertility

should be kept at around 100 ppm (N); excessive

levels of N can lead to a lush, dense canopy thatwill take longer to dry and will be more

susceptible to attack by the collar rot pathogen.

Plant debris should not be allowed to build up in

transplant trays or remain in contact with

seedlings. Clip seedlings at a low blade speed

with a well-sharpened, high-vacuum mower to

ensure complete removal of leaf pieces in the

least injurious way possible. Frequent clippings

will reduce the amount of tissue that must beremoved by the mower and will cause less plant

injury and lead to less leaf material left on thetransplants. Clippings and diseased plants

should be discarded a minimum of 100 yards

from the transplant facility, or buried. Home

gardens should not be planted near transplant

facilities, and keep a weed-free zone around

float beds. Over 300 species of plants, including

many weeds, are hosts to S. sclerotiorum,

making many weeds potential hosts for this

pathogen.

Figure 2. Clusters of collar-rot affected transplants

collapse, leaving open holes in the plant canopy.

Figure 3. Stems of collar rot-affected seedlings showing

wet necrosis that is amber-to-brown in color, beginning

at the base of the plant and extending upward.

Figure 4. Collar rot: white, cottony mycelium

(fungal mass) present if humidity is high, and

irregularly shaped, black sclerotia.


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WHEAT

New Tool for Assessing Fusarium Head

Blight (Head Scab) and Deoxynivalenol

(DON) Risk in WheatBy Don Hershman

Fusarium head blight (FHB) of wheat (Figure 5),

and deoxynivalenol (DON) accumulation in

harvested grain was a serious problem in 2009,but each year brings with it new possibilities.

The weather conditions in Kentucky thus far in

2010 have not been anything like they were in

2009. As a result, the FHB/DON risk has been

minimal. This could, however, change, Sincewheat is now heading out in much of the state, it

behooves you to pay close attention to the FHB

risk over the next 2-3 weeks.

An exciting new tool can be used to help you

determine the FHB risk and need to spray a

fungicide. This tool is a web-based, disease

forecasting model made available by Penn State

University, The Ohio State University, Kansas

State University, and the U.S. Wheat and Barley

Scab Initiative. This model, utilizes real-time

weather data from numerous National Weather

Service stations within each state. For

Kentucky, weather data included in the disease

model have been significantly ramped-up due

to the addition of about 50 Kentucky Mesonetweather stations(www.kymesonet.org/).

Go towww.wheatscab.psu.edu/and click onRisk map tool, then select the state of

Kentucky to see the current FHB risk for

Kentucky (Figure 6). The commentary section at

the bottom of the map is a place where I have

the opportunity to write a brief summary of the

current risk and model output and put them inproper context to things such as crop stage.

Hopefully, FHB and DON will be minor in thestate and region this year.

FRUIT CROPS

Leaf Wetness Promotes Apple and Grape

InfectionsBy John Hartman

Kentucky fruit growers, once faced with dry

weather, are now faced with spring rains

providing prolonged leaf wetness periods.Disease-causing fungi produce microscopic

spores which, in the presence of surface

moisture on susceptible plant parts, will

germinate (like a seed) and grow into the plant

and live as a parasite, causing disease. Rainy

spells during the weekend of April 24-25 plus

the early part of this week have provided

sufficient leaf wetness statewide for severe

Figure 5. Typical symptoms of Fusarium Head

Blight.

Figure 6. Kentucky screen for Fusarium Head Blight risk

Assessment Tool.
http://www.kymesonet.org/http://www.kymesonet.org/http://www.kymesonet.org/http://www.wheatscab.psu.edu/http://www.wheatscab.psu.edu/http://www.wheatscab.psu.edu/http://www.wheatscab.psu.edu/http://www.kymesonet.org/


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infections of apple scab, apple cedar rust, and

grape black rot.

Apple scab. Apple growers can examine tables

in the Midwest Tree Fruit Pest Management

Handbook (U.K. Extension Publication ID-93)

that spell out how much leaf wetness is neededto obtain apple scab and cedar-apple rust

infections. Table 1 shows data extracted from

ID-93 indicating that at temperatures in the 60'sand low 70's F, apple scab infection can occur in

as little as 6 hours when leaves are wet. With

recent statewide leaf wetness periods lasting at

least 15 hours, and up to 37 hours in some cases,

apple scab infections surely occurred onunprotected susceptible apples and crabapples.

Even with temperatures in the 50's extended leaf

wetness duration exceeded the minimum hours

needed for infection in most Kentucky locations.

Table 1. A proposed revision for the

minimum number of hours of leaf wetness

required to produce apple scab infections.a

Average

temperature (F)Hours

34 41

39 28

45 15

50 11

54-56 8

61-75 6

79 11a Data of W. MacHardy and D. Gadoury; and

A. Stensvand, et al., Cornell University.

Cedar-apple rust. Table 2, also extracted from

ID-93, shows leaf wetness needed to obtain

cedar-apple rust infections. The first number

listed is for situations where the cedar-apple rust

inoculum (orange, swollen galls bearing

teliospores with basidiospores on cedar trees) is

available at the start of the rain. If inoculum is

not already present (dry period prior to the rain),

the second number incorporates the added

wetness hours needed for infection. Infection is

unlikely at temperatures below 43F if inoculum

is not already present. Temperatures favorable

for cedar rust infections are similar to those for

apple scab. Cedar-quince rust, which infects

apple fruits, appears on cedar trees at the same

time as cedar-apple rust and infection

requirements may be similar.

Table 2. Approximate minimum number of

hours of leaf wetness required for cedar-apple rust infections on leaves of

susceptible cultivars.

Average

Temperature (F)

Hours (Second

number represents

hours needed for

infection if wetness is

preceded by a dry

period.)

43 8 - 14

46 6 - 12

50 6 - 12

54 4 - 8

58-64 3 - 7

68 to 76 2 - 6

79+ -

Based on the data of Aldwinckle, Pearson, and

Seem, Cornell University.

Grape black rot. Infections by the black rot

fungus also depend on leaf wetness. Table 3

presents data extracted from the Midwest SmallFruit Pest Management Handbook, Ohio StateUniversity Extension publication Bulletin 861,

available through the UK Cooperative Extension

Service. Note that the grape black rot infections

are favored by warmer temperatures than apple

scab or cedar rust infections.

For both apple and grape, infections can occur

on any green tissue exposed to the fungal spores

during wet periods. Fruit growers are urged to

take note of the weather and take needed action

to prevent primary infections from becoming

established during these moist periods. Fruit

disease management suggestions are available at

County Extension Offices statewide.


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Table 3. Grape Black Rot. Leaf Wetness

Duration-Temperature Combinations

Necessary for Grape Foliar Infection by

Black Rot.

Temperature F Minimum Leaf

Wetness Duration(Hr) for Light

Infection

50 24

55 12

60 9

65 8

70 7

75 7

80 6

85 9

90 12Data represent a compilation from several

experiments with the cultivars Concord,

Catawba, Aurora, and Baco noir.

SHADE TREES

Winter Injury in the LandscapeBy Bill Fountain, Extension Horticulturist

and Julie Beale, Plant Diagnostician

The last frost and the arrival of spring let us put

winter behind us, at least in our minds.

Unfortunately for individuals managing

landscapes and diagnosing plant problems, it is

the onset of the visible symptoms of winter

injury. The visual effects of winter injury can be

evident into summer. Over the long term, winter

related stress can increase susceptibility to

disease and insect attack. Most of the injury we

see is the result of either chilling (low

temperature) injury or desiccation.

Chilling Injury

Development of winter hardiness is not an off

and on process like switching on a light. The

development of cold hardiness is a complicated

process that increases and decreases slowly as

the seasons progress. Hardiness begins to

develop as growth slows and stops, finally

culminating in mid winter. It then gradually

decreases until growth begins in earnest. The

often referenced USDA Plant Hardiness Zone

Mapping system refers to a best case scenario of

what a plant can tolerate in mid winter without

significant injury or death. However, plants do

not remain uniformly hardy throughout thewinter. A plant hardy to -20F in January can be

killed by a light frost after the start of spring

growth. In fact, most of our chilling injury

occurs as a result of sudden cold snaps in fall

and late frosts in spring. This is why just

knowing the lowest temperature of the winter

may not provide enough information for

diagnosis.

Symptoms of chilling injury vary depending on

which plant tissues were vulnerable at the time

of exposure. In succulent tissues, such as leavesand stems, water freezing in the cells forms

crystals that expand, rupturing cell walls. Cell

contents leak out of the cell, giving leaves and

stems a water-soaked appearance. Tissues

damaged in this way will not recover. If the

damaged tissues can be cut back to a healthy

bud, the plant will produce new shoots.

Flower buds are often slightly less hardy than

vegetative buds and may be killed, leaving only

the buds that develop into leaves and stems.

Forsythia (Forsythia x intermedia) is a commonlandscape plant that seems to forget to flower

after severe winters with extremely low

temperatures, usually -15F or lower. The flowerbuds are killed during these extremely cold

periods, but the plant is still able to produce new

vegetative growth with the arrival of spring.

Although poor spring flowering is a

disappointment to gardeners, flowering everyyear is not essential to the plants survival the

way that vegetative growth is.

The cambium is a thin layer of cells just belowthe bark that divides to form newphloem cells(downward conduction of sugars) to the outside

and newxylem cells (upward conduction of

water and mineral elements) to the inside. These

cambium cells begin to divide and grow long

before we see new leaves and shoots in earlyspring. During unseasonably warm periods, the

cambium can become active only to freeze with


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a sudden drop in temperature. When this occurs

on the trunk it is called sunscald, though it is

really caused by freezing after the sun has

warmed these cells. It appears first as a thin

vertical crack in the bark and is often on thesouth or southwest side of the trunk (Figures 7

& 8). It occurs more commonly on young treesthan old ones. Species with thin bark are

particularly susceptible, including red maple

(Acer rubrum), magnolia (Magnolia spp.),apple/crabapple (Malus spp.) and linden (Tiliaspp.). Sunscald may result in the sloughing off

of bark, but it is imperative to resist the urge to

peel off the bark, as this only aggravates the

damage. Binding the loose bark has not proven

beneficial nor has painting the wound. The best

recommendation is to install plants with large

root balls, water during dry periods in winter and

provide optimum growing conditions for thespecies. Should this type of damage occur,

recovery is more rapid in healthy, vigorous

plants than in those under stress. Keeping

irrigation water off the wound will also help to

reduce the potential for decay.

The least hardy part of any plant is its roots.

Roots normally are protected from extremes of

temperature and drought by soil. Plants growing

in containers or sitting on the surface as balled

and burlapped plants are subject to root injury

from exposure to the frigid air temperatures ofwinter. Low temperatures may kill the roots

without damaging the more hardy stems andbuds above ground. When the plant does not

leaf out in spring, scraping the stem and buds

reveals green, moist tissues. Often there is

enough moisture in the stems to allow the buds

to pop as the weather warms but not enough toallow shoots to elongate or leaves to develop.

Without live roots to absorb moisture the shoots

and buds soon desiccate and die. There is no

treatment for plants that have lost their entire

root systems from exposure to low temperatures;prevention is the only cure.

Desiccation

While moving air does not make plants colderthan the actual temperaturethe way wind

chill makes usfeel colder--it can increase the

rate of water loss from the plant, particularly in

broadleaf evergreens (Figure 9). Water loss is

further compounded in evergreens when they are

exposed to direct winter sun. The sun warms the

foliage while the soil and stems remain frozen,

preventing the absorption and upward movement

of water to replace what has been lost from thewarmed leaf. This often does not become

evident until early to mid spring when the planttakes on a tan or brown appearance. If the leaf

turns brown but the buds remain alive and green,

the plant is generally able to recover. Boxwoods

(Buxus spp.), cherrylaurel (Prunus

laurocerasus), rhododendron and evergreen

azalea (Rhododendron spp.) are plants that often

experience this type of damage.

Winter injury appears in many different forms

and can often be the initiating stress that results

in disease or insect attack. Matching the

appropriate plant to the site, proper mulching infall and other cultural techniques to reduce stress

help give the plant the optimum chance to thrive.

Figure 7. Sunscald injury

to the trunk as it first

becomes noticeable.

Figure 8. Old sunscald

injury with the

development of decay

and borer attack.

Figure 9. Winter drying

of broadleaf evergreen

foliage (Ilexsp.).


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Emerald Ash Borer Trapping BeginsBy Lee Townsend

Those who

live or

travel in

Kentuckythis

summer

probablywill see

purple

prisms

hanging at

least 10 feet above the ground in ash trees.

These prisms are traps for the emerald ash borer,

a destructive insect that was found in Kentucky

during the summer of 2009.

About 6,000 traps

are being installed

as part of an

emerald ash borer

survey funded by

the U.S.

Department of

Agriculture

Animal Plant

Health Inspection

Service, and U.S.Forest Service.

The Office of the

State

Entomologist is overseeing the installation of the

traps.

Traps are placed in a grid pattern about 1.5 to 2

miles apart along the leading edge of the

quarantine area established after the insect wasdiscovered in the state in last year. The

quarantine applies to an area in north central

Kentucky roughly between Louisville,Lexington, and Covington and Greenup County.

Traps also will be placed at rest areas,campgrounds, state parks and other tourist

attractions across the state. They will be

collected and examined for the insect in August,

after the flight period has ended.

The traps are about 2-feet-long and baited withan attractant to lure the borers if they are already

present in the area. The traps are harmless to

humans, animals, and trees. They do not contain

toxic material and will not cause new

infestations to develop.

The emerald ash borer is a small, dark green

metallic beetle that attacks all species of ash

trees. Adult borers feed on a tree's leaves duringMay and June. The larvae burrow into the tree to

feed under the bark from July thru October,

destroying the tree's ability to transport water

and nutrients. This can cause loss of the entire

canopy and ultimately kill the tree within a yearor two.

If emerald ash borer infestation is suspected,

contact the USDA-APHIS Emerald Ash Borerhotline at 866-322-4512 or the Kentucky Office

of the State Entomologist at 859-257-5838.

Information on the status of this insect in

Kentucky is available at

http://pest.ca.uky.edu/EXT/EAB/welcome.html

Yellow Poplar WeevilsBy Lee Townsend

Yellow poplarweevils, also

known as sassafras

and magnolia

weevils, are small

dark snout beetles

that feed on yellow

poplar, sassafras,

and magnolia buds

and leaves. Every

few years they are

abundant enough

to attract attention.

Damage from this insect comes in two forms.

Adults chew holes in buds and leaves that

resemble curved rice grains. The legless larval

stage lives as a miner in the leaves of poplar and

sassafras. Combined feeding by adults and

larvae can cause significant leaf loss. While

injured leaves are unsightly, the damage

Figure 10. Counties in blue show 2010

trapping area.

Figure 11. Purple pyramid trap

for emerald ash borer.

Figure 12. The long snout on

the yellow poplar weevil causes

it to be mistaken for a tick.
http://pest.ca.uky.edu/EXT/EAB/welcome.htmlhttp://pest.ca.uky.edu/EXT/EAB/welcome.htmlhttp://pest.ca.uky.edu/EXT/EAB/welcome.html


9/13

probably does not harm the health of establishedtrees. Aesthetic damage to landscape trees in the

form of browned or scorched-looking leaves and

premature leaf drop may be considered

unacceptable.

Shade tree and ornamental insecticides such ascarbaryl (Sevin), or products containing one of

the pyrethroids - cyfluthrin, permethrin, or

cyhalothrin may be used to reduce damage to thefoliage and subsequent mining. Treat when adult

feeding damage is seen on about 10% of the

branches and repeat as necessary. Weevils arrive

at trees over an extended period; treating at the

very first sign of damage may be premature and

require an additional application in a few days.

While the damage may be unsightly, the injury

to large, established trees in landscapes or

wooded areas probably will not harm the tree.

Adults pass the winter in leaf litter. They feed

from late April into early May. Before bud break

the weevils attack the swelling buds leaving

their distinctive feeding marks. As the leaves

unfold and enlarge, they, too, are fed upon. Eggs

are placed in the midrib on the underside of the

leaves, sometimes breaking the midrib. Newly-

hatched larvae move from the midrib into the

leaf. The mined portion of the leaf turns brown

and takes on a scorched appearance. When ready

to pupate, the larvae move to an inflated portionof the mine and spin a spherical silk cocoon.

Duration of the different life stages varies withenvironmental conditions. New adults begin to

emerge from leaves during the second week of

June and feed on the foliage. By mid-July the

adults have disappeared to their hiding places in

leaf litter and will remain inactive until spring.There is one generation of this insect each year.

Pine Bark Adelgid Snowy & Showy

By Lee Townsend

Snow on white pine bark isnt completely out of

the question in Kentucky but usually it is due to

an insect the pine bark adelgid - rather than

frozen precipitation. Pine bark adelgids are

small, dark, aphid-like insects that are covered

with a cottony wax secretion. They are most

common on white pine but can infest Scots,

Austrian, and other species, primarily in homelandscapes, parks, or nurseries. Needles on

heavily infested trees may turn yellow; small

trees may be stunted or killed by this insect or

other stresses that affect vigor.

These sap feeding insects occur on the smooth

bark of trunks and limbs. Heavy infestations

look like a covering of whitewash. While some

can be found at the bases of needles or on

terminal buds, these insects feed only on bark.

Females overwinter and lay their eggs in the

spring. The adelgids reproduce repeatedly so

there are several generations each year.

Practices that promote tree health can aid the

tree in dealing with the insect. A variety if

natural enemies, including fly maggots and lady

beetles provide natural control. Horticulture oil

can be applied during the winter months;

insecticidal soap can be used against crawlers in

the spring if needed.

LAWN & TURF

Nematodes and TurfgrassesBy Paul Vincelli

Interest among golf course superintendents in

nematodes--tiny roundworms that attack

turfgrass rootshas been growing in the pastcouple of years. This article reviews some of

the important points regarding turf nematodes.

Should I be concerned about nematodes?

Probably not in most turfgrass settings. Parasiticnematodes can be commonly found in turfgrass

soils, but in most situations (lawns, most athletic

fields, most fairways), their numbers are so low

that they dont warrant concern. Nematodes

commonly are a greater threat in high-sand soils,

Figure 13 & 14. Pine bark adelgid infestation (A. Sears

photos).


10/13

and most Kentucky soils are silt loams or

heavier. However, on high-sand soils (many

golf greens, certain tees and athletic fields), we

sometimes do find high levels of nematodes that

raise flags.

It is possible that nematodes are increasing inimportance in turfgrass management, for several

reasons:

1. High-sand content root zones havebecome common in golf greens and

certain other management settings.

2. The very low mowing heights that havebecome industry standards on golf

greens allow all root-infecting

organisms to be more destructive than

they would be otherwise.

3. Newer insecticides are more selectivethan in previous decades. In the past,applications for insect control probably

also provided some nematode

suppression.

4. Global warming increases the risk ofwintertime survival of nematodes. (FYI,

many members of the general public

think that the possibility of global

warming is controversial among

scientists. Its not, at least not among

professionally active scientists. And

what about the cold winter we just

experienced? Well, keep in mind thatthe phenomenon is called global

warming, not Kentucky warming.Weather varies across the globe, but

look at global temperatures.)

Which kinds of nematodes attack turfgrasses?

Nematodes can be characterized as ectoparasiticor endoparasitic. Ectoparasites are those that

feed while

physically

outside the root

(Figure 15).Endoparasitic

nematodes

burrow into the

plant in order

to feed (Figure

16). The

endoparasites

are commonly difficult to control, since theyspend most of their time protected within the

root

.

The most important genera of turf-attacking

nematodes in our region include:

Sting nematode (genus nameBelonolaimus). This highly destructive

ectoparasite, native to regions further

southeast, has reportedly been found

recently in cold-winter states including

Kentucky, Kansas, and southern Illinois.

It typically needs soils with 80+% sand

to reach damaging populations. As an

ectoparasite, it can be easily treated withnematicides.

Lance nematode (genus nameHoplolaimus). This nematode is a

migratory endoparasite, which means it

tears up roots internally as it pushes

through and feeds. As an endoparasite,

it is difficult to control with nematicides.

Root knot nematode (genus nameMeloidogyne). This endoparasite

(pictured in Figure 16) produces tiny

galls on roots (Figure 17).

Ring nematode (genus nameMesocriconema). High populations of

this ectoparasite are usually needed for

turf damage to occur, but a few

Kentucky golf greens have been foundwith damaging levels. Creeping

bentgrass is a major host.Figure 15. Ectoparasitic nematode

feeding on root hair. Note the

spear-like stylet it uses to pierce the

plant cell (Ann MacGuidwin, Univ.

Wisconsin photo).

Figure 16. Endoparasitic nematod (the swollen

body is stained red) feeding on the vascular

cylinder of a root and expelling eggs outside the

root (Ann MacGuidwin, Univ. Wisconsin photo).


11/13

Stubby root nematode (genus nameTrichodorus). This ectoparasite feedson root tips, resulting in a distorted root

system. Creeping bentgrass and

bermudagrass are common turfgrass

hosts.

What does nematode damage look like?

Most of the time, nematodes feeding on

turfgrass roots results in diffuse, irregular areas

of yellowed, wilting, thinning turf. In other

words, aboveground symptoms are not

distinctive. If the attack is severe enough, it can

result in death of turfgrassagain, usually in

diffuse patches rather than distinctive patterns

(Figure 18).

Nematode damage usually appears as diffuse,

irregular areas because the nematodepopulations themselves are very patchy in the

soil. Some parts of the green can have very high

counts, other parts very low counts.

Among turfgrass nematodes, the root knotnematode is the only exception to the rule of

damage being in diffuse, irregular areas. Attack

by this nematode has often been associated with

roughly circular patches of yellowish turf(Figure 19).

How can I find out if nematodes are causing

problems?

Simple: Sample the soil and have it tested.

Thats really the only way to know. Some

guidelines for sampling soil:

Dont sample using a cup-cutter: itwont give the most accurate counts.

Using a soil probe, collect 16-20 soilcores, 3-4-inches-deep per green.

If damage is visible, sample frommargins of affected area (sick grass, not

dead grass)

If no damage is visible, sample in anarbitrary zig-zag.

Leave the turfgrass plug in place. Thatallows the nematologist to check forendoparasites.

Combine cores into plastic bag (onesample per green) and seal. If using aziplock bag, tape it shut so it doesnt

break open in shipment.

Label bags with permanent marker. The sample must be protected from heat,

direct sunlight, and drying.

Figure 17. Galls on turfgrass roots caused by theroot knot nematode (Alan Windham, Univ.

Tennessee photo).

Figure 18. Severe

damage from the sting

nematode on a golf

green (Alan Windham

Univ. Tennessee photo

Figure 19. Circular

patches of yellowing

creeping bentgrass

caused by the root kn

nematode (Billy CrowUniv. Florida photo).


12/13

Samples can be submitted to severallaboratories, including the following:

1. University of Florida Nematode AssayLaboratory

(http://edis.ifas.ufl.edu/sr011). The UF

lab is collaborating with us to survey

nematodes in golf greens this year, sowe encourage submission of samples to

this lab in 2010, in order to have as

representative a database as possible.2. Purdue University Nematology

Laboratory

(http://extension.entm.purdue.edu/nemat

ology/index.html)

3. Mississippi State University(http://msucares.com/pubs/misc/m1230.

pdf)

Management of nematodesNematode control isnt as simple nowadays as it

was in years past. Many nematicides have been

removed from the market, because of risks to the

environment or human health. There are

alternative nematode control products on the

market, but golf course superintendents shouldexercise healthy skepticism about their efficacy.

Almost all of these products havent been

independently tested or, if they have, they have

performed poorly.

Keep in mind the following agronomicconsiderations regarding nematodes:

If you find nematodes on a problemgreen, they may not be the primary

stress.

Nematode activity on roots becomesmore damaging to the grass with lowermowing heights.

If nematodes produce shallow roots onthe grass, manage fertility and irrigation

accordingly.

PESTS OF HUMANS & ANIMALS

Black Flies Attack People and LivestockBy Lee Townsend

Black flies or buffalo gnats belong to a family of

small biting flies that develop in riffles or

flowing water of river and streams. Black flies

have been a chronic problem along the

Tradewater River in Webster County over the

past few years and an unusual nuisance in areas

of Adair, Logan, and Warren counties this

spring.

Black flies

spend the

winter as larvae

attached to

submerged

rocks and

snags. There is

a synchronized

emergence of

adults as the

water

temperaturerises in the

spring. This can result in a large emergence of

hungry adults that will fly off in search of a

blood meal.

These small humpbacked flies have blade-like

mouthparts similar to a horse fly. They slice the

skin and feed on blood that pools up at the

wound. Clouds of these flies can attack horses

and cattle near flowing water. The intense

feeding period lasts about 3 weeks before the

flies disappear.

Fly wipes or sprays for horses and cattle can

provide some relief. A thick coating of

petroleum jelly can deter feeding in horses earsbut must be re-applied every few days. An open

barn or shed provides a hiding place from these

day-feeding flies. The nuisance species in

Kentucky will swarm around the faces of people

but apparently do not bite. Repellents may give

some relief but there are no good control

measures for the adults.

In the late 1800s and early 1900s the southernbuffalo gnat was a serious pest of livestock

along some western Kentucky waterways.

Smoke from smudge fires was one of the few

ways to provide some relief for horses, mules,

and cattle that were tormented by these day-flying blood feeders. Animals could at least

stand in the smoke to escape bites. They still are

Figure 20. Black fly - about 1/16

inch long with humpbacked body

and banded legs.
http://edis.ifas.ufl.edu/sr011http://edis.ifas.ufl.edu/sr011http://edis.ifas.ufl.edu/sr011http://extension.entm.purdue.edu/nematology/index.htmlhttp://extension.entm.purdue.edu/nematology/index.htmlhttp://extension.entm.purdue.edu/nematology/index.htmlhttp://extension.entm.purdue.edu/nematology/index.htmlhttp://msucares.com/pubs/misc/m1230.pdfhttp://msucares.com/pubs/misc/m1230.pdfhttp://msucares.com/pubs/misc/m1230.pdfhttp://msucares.com/pubs/misc/m1230.pdfhttp://msucares.com/pubs/misc/m1230.pdfhttp://msucares.com/pubs/misc/m1230.pdfhttp://extension.entm.purdue.edu/nematology/index.htmlhttp://extension.entm.purdue.edu/nematology/index.htmlhttp://edis.ifas.ufl.edu/sr011


13/13

quite a nuisance. The nuisance and annoyance

occurs early in the year and then diminishes.

PESTICIDE NEWS & VIEWS

Belay 2.13 SC Receives Expanded Use Label

for Fruits and VegetablesBy Ric Bessin

Valent just announced that the EPA has

approved an expanded label for its insecticide

Belay 2.13 SC to include additional uses on

fruits and vegetables. Belay is a general-use,

neonicotinoid insecticide with the active

ingredient clothianadin and has a Caution

signal word and a 12 hour reentry interval (REI).

It is now labeled for soil andfoliar applicationson brassica leafy vegetables (21 day PHI -

cabbage, broccoli, cauliflower, collard greens,

mustard greens, turnip greens), cucurbit

vegetables (21 day PHI - melons, squash

pumpkins), fruiting vegetables (21 day PHI -

tomato, pepper, eggplant), leafy vegetables (21

day PHI - lettuce, spinach, Swiss chard, parsley),

tuberous and corm vegetables (14 day PHI -

potato, sweet potato), and grape (0/30 day PHI).

It is label for foliar applications on peach (21

day PHI), pome fruit (7 day PHI - apple, pear),

and tree nuts (21 day PHI). Soil applications arerestricted to at planting for many of these crops.

It target control of sucking insects (includingaphids, leafhoppers, mealybugs, stink bugs,

thrips, scale) and some chewing insects

(including Colorado potato beetle, flea beetles,

Japanese beetle, grape berry moth, plum

curculio, Oriental fruit moth).

Tourismo Labeled for Some Fruit CropsBy Ric Bessin

Ninchino American has labeled the insecticide

Tourismo for several fruit crops that are grown

in Kentucky. Tourismo is a general-use, premix

insecticide that contains the active ingredientsflubeniamide and buprofezin and bears the

signal word Caution with a 12 hour reentry

interval. Tourismo does require a 15-foot buffer

strip or permanent vegetation between the

treated area and down gradient aquatic habitat.

It is labeled for grapes (7 day PHI), pome fruit

(14 day PHI apple, pear), and stone fruit (14

day PHI peach, plum, cherry). This premix

controls Lepidopteran and Homopteran pests.

DIAGNOSTIC LAB HIGHLIGHTSBy Julie Beale and Paul Bachi

Recent samples in the PDDL have included

nitrogen deficiency on wheat; Sclerotinia collar

rot, target spot, cold injury and nitrogen

deficiency on tobacco transplants; leaf curl on

peach; black knot on cherry; growth regulator

injury, cold injury and sunscald on tomato

transplants.

On ornamentals we have seen rust on hollyhock;

Phytophthora root rot on arborvitae; Phomopsis

gall on forsythia; and winter injury on holly,

magnolia and juniper.

kentucky pest news april 27, 2010

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