kentucky pest news april 12, 2011

8/7/2019 Kentucky Pest News April 12, 2011

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Online at:www.uky.edu/KPN

Number 1263 April 12, 2011

ALFALFA

-Sclerotinia Crown and Stem Rot of Alfalfa

TOBACCO-Disease Update for the Week of April 11

VEGETABLES

-EPA Approves the Use of Mancozeb on

Peppers and other Maneb-Only Vegetables-Recognizing Late Blight on Tomato Seedlings

WHEAT-2011 Wheat Fungicide Efficacy

FRUIT CROPS

-Fruit Disease Forecasting Using Kentucky

Mesonet Weather Data

ALFALFA

Sclerotinia Crown Rot and Stem Rot of

Alfalfa

By Paul Vincelli

Sclerotinia crown and stem rot (SCSR) was

diagnosed last week in western Kentucky,

causing substantial damage to a fall seeding of

alfalfa. This disease attacks fall-seeded stands

because the fungus produces spores in the

autumn, mostly from mid-October through

November. Spring-seeded stands usually have

adequate resistance to infection by the time

spores are produced. However, fall-seeded

stands are still vulnerable to infection, and so

they may suffer stand loss. The stand lossescaused by SCSR vary from minor to very severe

(Figure 1).

SHADE TREES & ORNAMENTALS

-Managing Flowering Crabapple Fire Blight

FOREST

-Periodical Cicada Emergence in West Kentucky

LIVESTOCK

-Time to Assess Eastern Tent Caterpillar (ETC)

Populations on Horse Farms

HOUSEHOLD

-Carpenter Bees

DIAGNOSTIC LAB HIGHLIGHTS

INSECT TRAP COUNTS

Symptoms and SignsSymptoms likely to be seen at this time of year

are as follows:

Yellowing, wilting, and browning ofrandomly scattered plants throughout

the planting. During humid conditions,

infected plants may exhibit white fungal

mycelium (Figure 2). These symptoms

are typical of ongoing infections, so

these fields will probably continue to

Lexington, KY 40546

Figure 1. Complete stand loss from a severe

outbreak of Sclerotinia crown and stem rot of

alfalfa.
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experience disease development for

several more weeks. If weather remains

generally cool and wet, disease

development could continue for as long

as 4-6 weeks. Sustained periods ofwarm, dry weather will arrest the

disease. Disease does sometimes cause complete

or nearly complete death of plants. In

other words, alfalfa seeded last fall may

simply fail to green up (as in Figure 1).For stands that were lush and vigorous

going into winter and then died during

winter, Sclerotinia crown and stem rot is

the most likely culprit (although not the

only culprit).

Look for fungal survival bodies called

"sclerotia" to diagnose this disease. The sclerotia

look like tiny black pebbles about 1/16 to 1/8

inch in size, with a white or gray center (Figure

3). They can be found attached to dead plants. If

plants have been rotted away, the sclerotia will

be scattered about on the soil surface where

plants once were present.

ManagementThere are a few alfalfa varieties that show partial

resistance to this disease. Complete resistance is

not available in commercial varieties, but partial

resistance can reduce stand loss caused by thisdisease. If considering a late-summer seeding, it

is important to use a variety that has been shownto exhibit partial resistance under field

conditions in Kentucky. This is important

because some of the worst disease pressure from

Sclerotinia crown and stem rot in the nation is inKentucky. Variety evaluations conducted in

other states are useful, but if a variety hasnt

been tested for resistance under Kentucky

conditions, it hasnt been adequately tested foruse in Kentucky.

The variety Phoenix has been shown to have a

significant level of Sclerotinia resistance underKentucky conditions, so that is certainly one to

consider for late-summer plantings. Be aware

that these varieties can still suffer stand loss

from the disease, but they will suffer

considerably less stand loss than the many

susceptible varieties on the market. Cimarron

SR is also a good choice from the standpoint of

Sclerotinia. Beyond these, I am unaware of

other varieties that have held up against the

severe disease pressure we sometimes get in

Kentucky.

Growers with crops sustaining outbreaks of this

disease should take this opportunity to determine

which fields are showing the problem. This will

help them identify fields in which to avoid fall

seeding in the future. The Extension publication

Risk Factors for Sclerotinia Crown and Stem

Rot in Fall-seeded Alfalfa

(http://www.ca.uky.edu/agcollege/plantpatholog

y/ext_files/PPFShtml/PPFS-AG-F-2.pdf) has

more information on the disease.

Figure 2. White fungal growth on rotting

alfalfa crown, indicating an active infection

of SCSR.

Figure 3. Black, hardened survival bodies of the

SCSR fungus (at arrow).
http://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdfhttp://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdfhttp://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdfhttp://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdfhttp://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdfhttp://www.ca.uky.edu/agcollege/plantpathology/ext_files/PPFShtml/PPFS-AG-F-2.pdf


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TOBACCO

Disease Update for the Week of April 11By Kenny Seebold

Current Problems

In last weeks issue of Kentucky Pest News (No.1262), we took a look at two common, early-

season diseases of tobacco seedlings

Rhizoctonia damping-off and target spot. A few

cases of each have been reported over the pastweek (Figures 4 and 5), and I would expect

more to come given the recent warm-up and

subsequent spate of overcast, rainy weather.

From a management perspective, growersshould be focusing on providing good

ventilation for their plants (as much as is

practical given the weather), maintaining proper

fertility (~ 100 ppm N), and applying fungicideson regular schedule. The choice of fungicide touse depends on the age of seedlings in the float

bed. Plants that are dime-sized up to those ready

to clip should be treated on a 5-7 day schedule

with a mancozeb fungicide such as Dithane DF,

Manzate Pro-Stick, or Penncozeb 75DF at a rate

of 0.5 lb/100 gal of spray mixture (1 tsp / gal).

After the first or second clipping, the best option

would be Quadris applied at a rate of 4 cc per 5

gal of spray solution. The solution should be

sprayed onto 1000 sq. ft. of float bead (roughly

400 trays) so as to achieve good leaf coverageand stem rundown. Quadris can be used only

once on seedlings in the float system, so growers

must switch back to a mancozeb fungicide if

additional treatments are required. Refer to

Kentucky Pest News No. 1262 (April 5, 2011)

for more information, or consult the 2011-2012

Kentucky-Tennessee Tobacco Production Guide

(University of Kentucky Publication No. ID-

160).

Tobacco Fungicide News

A rumor has been floating around about the useof Dithane DF (and other mancozeb fungicides)

on tobacco seedlings, specifically that Altria

(PM USA) has prohibited the use of these

products in the float system. I have spoken with

an Altria representative regarding this, and have

been informed that the company has not banned

mancozeb on tobacco either on seedlings or in

the field. Growers should not be concerned

about applying mancozeb on tobacco at this time

and should consider its regular use in the float

system to manage diseases like Rhizoctonia

damping-off and target spot.

Some growers have also asked if Ridomil Gold

SL is now legal to use in the float bed to managePythium root rot. This probably stems from

language in the 24(c) label that was recently

approved that allows the use of this fungicide in

transplant water at setting time (Kentucky PestNews No. 1261, March 29 2011). Ridomil Gold

can only be used in the field, and cannot be

applied to float water; Terramaster EC is the

only product labeled for control of Pythium root

rot in float systems.

Figure 4. Damping-off caused by Rhizoctonia solani on

young tobacco seedlings (Photo: Jay Hettmansperger).

Figure 5. Early-stage target spot on tobacco

seedlings (Photo: Jay hettmansperger).
http://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/KPN%20Site%20Files/kpn_11/pn_110329.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.htmlhttp://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.html


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VEGETABLES

EPA Approves the Use of Mancozeb on

Peppers and Other Maneb-Only VegetablesBy Kenny Seebold

In late 2008, all registrations for manebfungicides in the U.S. were cancelled by their

manufacturers. Maneb products are important

protectant fungicides used by many vegetableproducers in Kentucky and include Maneb 75DF

and Manex. There are also a number of maneb-

based home garden materials offered by

companies such as Hi-Yield and Bonide. The

main reason for the voluntary cancellation was

based on the high cost of maintaining the

Federal registration compared to the amounts

sold each year. Maneb was produced through

the end of 2008, and could be sold legallythrough the end of 2009.

The loss of maneb on certain crops took away an

important protectant fungicide and a valuable

tank-mix partner for fungicides that are prone to

the development of resistance. Whats more,

Kentuckys pepper growers have been advised

for years to mix copper fungicides with maneb

or the related fungicide mancozeb to help

improve control of bacterial leaf spot. It turns

out that these fungicides help make the copper

more effective against the bacterial pathogensthat cause this disease. Losing maneb has

therefore left us with a less-than-optimalchemical solution for pepper bacterial spot.

For some vegetable producers, the loss of maneb

has had very little impact. Growers who

produce sweet corn, cucurbits (except pumpkinsand winter squash), onions, potatoes, and

tomatoes can simply replace maneb with the

fungicide mancozeb, sold as Dithane,

Penncozeb, and Manzate. On the down side,

those who grow broccoli, cabbage, lettuce,peppers, pumpkins, and winter squash could not,

until recently, use mancozeb legally because of

label restrictions, even though maneb and

mancozeb are practically identical chemicals.

In early April, the EPA approved mancozeb for

use on several crops that had been previously

only on the maneb label broccoli, cabbage,

lettuce, and pepper. So far, only Manzate Pro-

Stick has this supplemental labeling, but other

mancozeb products (Dithane, Penncozeb) could

follow shortly. Late last year, approval was also

given to use mancozeb on pumpkins and wintersquash. The products that have the pumpkin /

winter squash labeling are Manzate Pro-Stickand Dithane DF. This is a great development for

pepper growers in particular, who now have a

replacement for maneb in the form of Manzate

Pro-Stick to use in tank-mixes with copper

fungicides to help suppress bacterial leaf spot.

As mentioned earlier, only Manzate can be used

on peppers, cabbage, broccoli, and lettuce fornow. For those growing pumpkins and winter

squash, either Manzate or Dithane can be used

as a direct substitute for maneb (Maneb and

Manex). Supplemental labels for either Manzate

or Dithane must be in the possession of thegrower when these products are used.

Recognizing Late Blight on Tomato SeedlingsBy Kenny Seebold

The vegetable growing season is upon us, and

garden centers are beginning to sell transplants

for homeowners. Commercial nurseries and

growers are also gearing up for transplanting.Tomatoes have always been a popular vegetable

crop for both home gardeners and commercialgrowers in Kentucky, and transplant-borne

diseases such as bacterial spot, bacterial canker,

and recently late blight, have caused serious

losses in some years.

ImportanceLate blight is an extremely important and

damaging disease of tomatoes and potatoes, and

occurs wherever these crops are grown. Until

recently, late blight was considered a minorproblem in Kentucky; however, a severe

outbreak in July, 2009 caused heavy losses to

home gardeners and commercial producers.

Although the source of this outbreak was neverdetermined, introduction on infected transplants

was suspected. In May, 2010, late blight was

confirmed on tomato transplants being sold by a

number of retail garden centers in central and


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northern Kentucky. No serious outbreaks

occurred that year because of the hot and dry

weather that prevailed, but losses would have

been high in a cooler, wetter summer due to the

sheer number of infected transplants that weresold to unsuspecting gardeners. Introduction of

this disease on transplants may or may not takeplace every year, but represents a threat to

tomato (and potato) producers in Kentucky.

Tomato seedlings that have late blight whentransplanted can serve as sources of inoculum

(spores) that can spread to nearby gardens and

commercial plantings, so every measure should

be taken to prevent these plants from making it

to the field. The added threat is that sources of

disease are introduced early in the tomato

production season, magnifying the potential for

heavy losses in seasons that favor late blight.

Learning to identify late blight on tomatoseedlings is extremely important for home

gardeners and commercial producers. This

knowledge will help prevent the unintentional

introduction of a devastating disease AND allow

other tomato and potato growers to be alerted to

a potential threat.

Symptoms and SignsOn seedlings, late blight first appears as circular-

to-irregularly shaped, water-soaked blotches on

leaves, petioles, and stems that expand rapidly

under favorable conditions (Figures 6 and 7). Inhumid environments, white and fuzzy fungal

growth may be present and indicates that spores

are being produced and released into the area.

Extensive blighting of foliage follows; death of

seedlings is common where stem infections

occur. If conditions become unfavorable for

disease after the appearance of symptoms,lesions can dry out, leaving brown-to-black

necrotic areas on foliage and stems.

Cause and Disease Development

Late blight is caused by Phytophthora infestans,a fungus-like organism belonging to a group of

microorganisms called oomycetes or water

molds. The late blight pathogen needs living

tissue to survive and does not generally

overwinter in Kentucky, as susceptible hosts are

killed during the cold winter months. The

pathogen does not survive on seeds, even if the

disease was present on the crop before seed were

extracted. Potential sources of inoculum(spores) that can affect tomato seedlings for

personal use or sale in Kentucky include:

volunteer potatoes; infected tomatoes in

greenhouses or other protected environment;

imported, diseased, planting material; and spores

blown in from areas where late blight is active.Tomato plugs or seedlings produced out of state

are thought to become exposed to the late blight

pathogen from infected volunteer tomatoes andpotatoes, susceptible weed hosts, or susceptible

plants such as tomatoes, eggplants, and petunias

(related to tomatoes) grown in greenhouses.

Late blight is most aggressive during periods ofcool and wet weather. The ideal climate for

infection and development is characterized by

cool nights (50-59o F) and warm days (70-79o F)

along with frequent periods of rain, fog, orheavy dew. Disease development is slowed or

stopped at temperatures above 86o

F, although

the pathogen can remain dormant in infected

tissue and re-emerge if temperatures fall back to

the disease-favorable range. During favorable

conditions, symptoms will appear around 5 days

after infection occurs, and spore production will

begin on infected tissue 1-2 days later. Large

numbers of spores are produced, and are then

spread by wind, water splash, or mechanical

contact. Thus, the disease can spread rapidly in

transplant production facilities and retail outlets.And once infected tomatoes make it into gardens

and commercial fields, a large-scale epidemic is

likely if weather is cool and rainy for extended

periods of time.

Tips for Buying Healthy Tomato Seedlings1. If possible purchase plants grown

locally from seed and not plugs brought

in from out-of-state. The risk from lateblight is generally lower on these types

of plants than on imported, finished

plants or locally-grown plants producedfrom imported plugs.

2. Look carefully at all plants on displayfor the characteristic symptoms and

signs of late blight (refer to figures).

The disease may be evident on just a

few plants in a garden center at first, andsymptoms will be mild. The disease

often develops earliest in shaded areas


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of the retail bench, particularly beneath

overhanging racks. Left unmanaged, the

disease can affect large numbers of

seedlings in a short time frame.

3. If you suspect that plants are infected bylate blight, alert your local Cooperative

Extension representative as quickly aspossible. Suspect plants need to be

tested quickly to confirm the presence of

late blight. This is important becausecertain diseases or environmental

problems can mimic late blight, and

laboratory tests are needed to provide a

positive identification. Do not buy

plants from retail outlets where late

blight is suspected until testing is

complete. It may seem reasonable to

just buy the healthy-looking plants

around those that appear to be diseased,but there is still risk if late blight is

active in the retail center. It takes

several days from the time a plant is

infected by the late blight pathogen to

the appearance of symptoms. Plants that

seem healthy could actually have the

disease and would certainly show

symptoms once brought home and

planted. If tests come back negative, it

should be safe to plant seedlings

purchased from that particular retail

outlet.4. Do not purchase tomato seedlings from

a retail center where late blight has beenconfirmed until all plants have been

destroyed and new, healthy stock

brought in. In cases where late blight is

confirmed in retail outlets, Cooperative

Extension will work with storemanagement to help bring the problem

under control.

5. As an added measure of safety, considerholding purchased plants in an isolated

area for a week before transplantingthem in the garden or field. Water the

plants as needed and watch for the

appearance of symptoms of late blight

(or other diseases and even insects).Plants that appear healthy after this

period will likely be safe to plant. If late

blight (or another problem) is suspected,

contact a representative of the

Cooperative Extension Service for

assistance in identifying the problem

before moving these seedlings outside.

WHEAT

2011 Wheat Fungicide EfficacyBy Don Hershman

Each year, the North Central Regional

Committee on Management of Small Grain

Diseases (NCERA-184) revises anddisseminates a fungicide efficacy table. Efficacy

ratings for each fungicide listed in the following

table were determined by field testing fungicides

over several years and locations by the members

of the committee. Efficacy is based on proper

application timing to achieve optimum

effectiveness of the fungicide as determined by

labeled instructions and overall level of disease

Figure 6. Darkened, irregular, and water-soaked

lesions on leaves or stems are typically seen on

seedlings affected by late blight.

Figure 7. Stem lesions typical of late blight on

tomato seedlings. These lesions may girdle the

stem and kill growth above that point.


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Propiconazole11.7%Azoxystrobin 7.0%

Quilt 200 SC14.0

VG VG VG VG E E VG NL Feekes 10.5

Propiconazole11.7%Azoxystrobin13.5%

Quilt Xcel 2.2SE

5

14.0--

3VG --

3--

3--

3VG --

3NL Feekes 10.5

Propiconazole

11.4%

Trifloxystrobin11.4%

Stratego 250 EC10.0

G VG VG VG VG VG VG NL 35 days

Tebuconazole22.6%

Trifloxystrobin22.6%

Absolute 500SC

5.0G --

3--

3--

3--

3E --

3NL 35 days

1Efficacy categories: NL=Not Labeled and Not Recommended; P=Poor; F=Fair; G=Good; VG=Very Good; E=Excellent. Efficacy

designation with a second rating in parenthesis indicates greater efficacy at higher application rates.

2Efficacy may be significantly reduced if solo strobilurin products are applied after stripe rust infection has occurred

3Insufficient data to make statement about efficacy of this product

4Multiple generic products containing the active ingredients propiconazole and tebuconazole may also be labeled in some states.

Products including tebuconazole include: Embrace, Monsoon, Muscle 3.6 F, Onset, Orius 3.6 F, Tebucon 3.6 F, Tebustar 3.6 F,

Tebuzol 3.6 F, Tegrol , and Toledo. Products containing propiconazole include: Bumper 41.8 EC, Fitness, Propiconazole E-AG, and

PropiMax 3.6 EC.

This information is provided only as a guide. By law, it is the responsibility of the pesticide applicator to read and follow all current

label directions. No endorsement is intended for products listed, nor is criticism meant for products not listed. Members or

participants in the NCERA-184 committee assume no liability resulting from the use of these products.

FRUIT CROPS

Fruit Disease Forecasting Using KentuckyMesonet Weather DataBy Paul Vincelli, Extension Plant Pathologist

John Hartman, Extension Plant Pathologist

Tom Priddy, Extension Agricultural

Meteorologist

John Strang, Extension Horticulturalist

For a number of years, the University of

Kentuckys Agricultural Weather Center has

offered weather-based disease prediction models

for the benefit of apple and grape producers in

making disease management decisions. Untilthis year, predictions of disease models for fruit

crops have been based on weather data available

from fifteen National Weather Service (NWS)

stations located throughout Kentucky. However,

disease predictions that have a greater

geographic reach throughout the

commonwealth are now possible. This is

because of the growth in recent years ofKentuckys Mesonet Weather System.

The Kentucky mesonet is a research grade

network of automated weather and climate

monitoring stations being developed by the

Kentucky Climate Center at Western Kentucky

University (http://www.kymesonet.org/). The

Kentucky mesonet currently includes 56 weather

stations, with more expected as funding permits.

If we base fruit disease predictions on mesonet-based data instead of NWS data, we can use all

56 mesonet weather stations to feed into themodels. Using the data in all these mesonet

stations should result in improved diseaseprediction for fruit producers, since there are

more likely to be nearby weather stations in the

mesonet network than the NWS network.

However, before switching our diseasepredictions to mesonet-based data, we wanted
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some assurance that the weather data feeding

into the models would be similar between the

two systems. We conducted a series of analyses,

but well only present two here for the sake of

brevity. In both cases, we focused our analyseson estimating the duration of leaf wetness

periods, for the following reasons:1. Wetness of surfaces of leaves, flowers,

and fruit is essential for infection by

many plant pathogenic fungi andbacteria. Many, many disease models

for crops all over the world are based in

some way on estimating leaf wetness

duration, including the models we make

available to apple and grape growers

through the UK Cooperative Extension

Service.

2. Estimating leaf wetness duration is

notoriously difficult and imprecise,much more difficult than measuring air

temperature or rainfall.

For our analysis, we gathered weather data for

the period 8 Apr to 2 Oct 2010 at UKs Research

and Extension Center at Princeton. We used

data collected by three weather stations at the

same site: the NWS station, the mesonet station,

and a Spectrum Technologies WatchDog

weather station. (Periodically, during the past

dozen years, three WatchDog units--located in

Quicksand, Lexington, and Princeton--haveprovided weather data used to generate fruit

disease forecasts issued by Dr. Hartman.)Results of the two analyses selected for

inclusion in this article are shown in Figures 8-9.

In Figure 1, it is clear that estimates of leaf

wetness using Mesonet data correlate to thoseobtained using the NWS station. Variance is

clearly present in those estimations, and in some

instances the difference in estimated duration of

leaf wetness is substantial. However, there is no

evidence of a significant systematic bias in theestimation of leaf wetness between those data

sources.

Figure 8. Comparison of estimates of leaf wetness

duration obtained using data from two nearby weather

stations. These estimates were calculated based on an

algorithm employed by the UK Ag Weather Center.

In Figure 2, one can see that leaf wetness

estimates correlated well between the two data

sources used in this analysis. The mesonet data

showed a slight tendency to underestimate

periods of leaf wetness at values, especially

below 5 hr of leaf wetness, but this difference

was not large and probably wouldnt be

epidemiologically significant for most disease

outbreaks.

Figure 9. Comparison of estimates of leaf wetness

duration obtained using Mesonet data and a Spectrum

WatchDog unit. These were calculated using similar

algorithms (although the algorithm used on mesonet

data included wind speed, data which were not available

in the WatchDog unit).


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ConclusionThe growth of the Kentucky mesonet network

provides a more comprehensive weather

network for prediction of crop diseases than has

been previously available. Our analyses suggest

that disease forecasts based on these data should

be useful to fruit producers. Given theincreasing coverage of the mesonet network

(with currently 56 stations statewide), we expect

that the mesonet system will provide more local,fine-scale resolution than can be obtained with

either Spectrum WatchDog units located on UK

research stations or NWS weather stations

(which currently number 15 statewide). Disease

models incorporating mesonet data are available

http://wwwagwx.ca.uky.edu/kymesonet2.html.

SHADE TREES & ORNAMENTALS

Managing Flowering Crabapple Fire BlightBy John Hartman

Kentucky flowering crabapples, flowering now,

are enjoyed for their profuse flowers and for

their attractive foliage and fruit. Experienced

growers and homeowners are well aware that

springtime is also the time of year that many of

the important diseases of flowering crabappleare most active.

Many flowering crabapples are made unsightly

or are severely injured by one or more of fivecommon diseasesapple scab (discussed in

Kentucky Pest News two weeks ago), fire blight,

cedar-apple rust, cedar-quince rust, and powdery

mildew. Injury due to fire blight infection is

often obvious in the tree because in spring andearly summer, twigs and small branches are

dead and blackened.

Managing fire blight (Figures 10 & 11) causedby the bacterium Erwinia amylovora:

While trees are dormant, prune outshoots killed by fire blight the previous

year.

Remove water sprouts and root suckerswhen they are small.

Remove nearby neglected pear andapple trees from the nursery or

landscape because these trees can be a

source of overwintering fire blightbacteria.

Plant fire blight-resistant crabapples in

new plantings. Ratings vary from onepart of the country to the other,

however, the following cultivars are

thought to be more tolerant of fireblight: Adams, Adams Dwarf,

Callaway, Candied Apple,

Christmas Holly, David, Dolgo,

Harvest Gold, Indian Summer,

Jewelberry, Liset, Malus sargentii,

M. yunnanensis var. veichii, M. zumi

Calocarpa, Pink Princess, Pink

Spires, Prairiefire, Profusion,

Radiant, Red Baron, RobinsonDwarf, Royalty, Selkirk, Sentinel,

Spring Snow Dwarf, and Velvet

Pillar.

Antibiotic sprays such as streptomycincan be used to protect open flowers from

infection. Antibiotic sprays are bestused in the nursery, and not in the

landscape. Use of a computer model

such as Maryblyt or Cougarblight for

timing of fire blight sprays is most

useful.

Nursery growers may consider using thefire blight predictive system available toapple growers on the U.K. Ag Weather

Center site

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

2.html). The predictive system worksbecause the weather and fire blight risk

parameters are the same for apple and

crabapple. These predictive systems

have already indicated that flowering

crabapples with open flowers were athigh or extreme risk for fire blight

earlier this week on both Saturday andMonday. After flower petals fall in the

coming days, the risk of primary fire

blight infections drops to low levels.

However, from primary infections that

already occurred, secondary shoot

infection symptoms will continue to

appear for the next several weeks.
http://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.htmlhttp://wwwagwx.ca.uky.edu/kymesonet2.html


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For all but the most susceptible trees,infections are normally halted by thetree before the bacteria actually kill the

tree. Thus, infected branches are best

removed in winter.

Avoid promoting succulent growth that

favors fire blight.

FOREST

Periodical Cicada Emergence in WestKentuckyBy Lee Townsend

Periodicalcicadas

that make

up Brood

XIX soon

will beleaving the

quiet life

they have

been

leadingundergro

und as sap feeders on tree roots. After for 13years in the dark, nymphs will crawl up vertical

surfaces and molt to loud (males), active adults(both sexes) that will buzz around clumsily for

about 6 weeks.

These insects differ from the dog day cicadas

that we see near the end of every summer. Theyare smaller and have red eyes and red-orange

wing veins; these structures on the larger dog

day cicadas are green. Erratic fliers, cicadas

often stay in the upper canopy of trees where

they are active from late April through June.Encounters with periodical cicadas can be

unnerving but these insects cannot sting and do

not harm humans, livestock, or pets. Except for

the occasional dog or cat that will suffer an upset

stomach from eating too many.

The estimated time table for Brood XIX:

Emergence begins late April or early May

Most out by late May. Males begin to call

females for mating

Egg laying will begin in mid-May

Last adults will disappear around mid-June

Brood

XIX

will be

active in

westernKentuck

y and

Figure 10. Fire blight, shown here on a flowering

pear flower cluster, similarly attacks flowering

crabapple flowers before spreading to the

nearby branches.

Figure 11. Fire blight branch infection

showing typical shepherds crook symptom.

Figure 12. Periodical cicada molting to an

adult.

Figure 13. Counties where periodical cicadas

were active in 1998.


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parts of Alabama, Arkansas, Georgia, Indiana,Illinois, Louisiana, Maryland, Missouri,

Mississippi, North Carolina, Oklahoma, South

Carolina, and Tennessee.

Please send observations and pictures of the

brood [email protected]. Examples ofuseful information include your location, date

you first noted emergence, estimated abundance

(light moderate heavy), date males started

singing, egg-laying beginning, or other thingsyou find interesting. This information will be

posted at

http://pest.ca.uky.edu/EXT/Cicada/kycic2011.ht

ml

LIVESTOCK

Time to Assess Eastern Tent Caterpillar

(ETC) Populations on Horse FarmsBy Lee Townsend

Over the

past 3 years

ETC

populationshave been

increasing

gradually

but there

arerelatively

wide

differences

in numbers from one area to another. This is

normal for the dynamics of the insect.

ETC larvae should be mostly in the 0.5 to 0.75inch range in central Kentucky. The caterpillars

are beginning to move from 2- to 3-inch long

tents near their egg mass to larger masses at

major branch forks. Most tents should be in the

baseball to softball size, making them easy to

see in trees on a sunny day. Consequently, now

is the time to check for tents along pasture and

paddock tree lines that contain wild cherry, if

pregnant mares are present. Any management of

the caterpillars should be done while they are

together in tents. If is essentially impossible to

provide effective control once they have

dispersed from host trees.

One option is to move pregnant mares awayfrom identifiable concentrations of ETC. If this

is not practical, then physical removal of tents,

or spot treatment with insecticides is an

alternative approach.

ETC was identified at the cause of foal loss

during the Mare Reproductive Loss Syndrome

outbreak that occurred during 1999-2001.

HOUSEHOLD

Carpenter BeesBy Lee Townsend and Mike Potter

Carpenter

bees

(picture)

closely

resemble

bumble bees

but havebare, shiny

black

abdomens.

Bumble beeshave hairy

abdomens

with at least some yellow markings. Bumble

bees nest in the ground, while true to their name,

carpenter bees chew tunnels into wood toconstruct nesting sites.

Carpenter bees spend the winter in their galleriesand begin to feed on nectar and pollen aroundearly April. Females may begin a new nest or

use the existing one. The entryway is a round 0.5

inch diameter hole in the underside of a soft

wood board. The gallery soon turns 90 degrees

and follows the wood grain. Sawdustaccumulates beneath the tunnel opening as the

female extends it. The bees prefer bare or

Figure 14. ETC tent with massed

caterpillars.

Figure 15. Carpenter bee gathering

nectar and pollen.
mailto:[email protected]:[email protected]:[email protected]://pest.ca.uky.edu/EXT/Cicada/kycic2011.htmlhttp://pest.ca.uky.edu/EXT/Cicada/kycic2011.htmlhttp://pest.ca.uky.edu/EXT/Cicada/kycic2011.htmlhttp://pest.ca.uky.edu/EXT/Cicada/kycic2011.htmlhttp://pest.ca.uky.edu/EXT/Cicada/kycic2011.htmlmailto:[email protected]


13/13

weathered wood but a coating of paint or stain

will not guarantee the wood wont be used.

Liquid sprays of carbaryl (Sevin) or a pyrethroid

(e.g., permethrin or cyfluthrin) can be applied as

a preventive to wood surfaces which areattracting bees. Residual effectiveness of these

insecticides is often only 1-2 weeks, however,and the treatment may need to be repeated.

Tunnels which have already been excavated are

best treated by puffing an insecticidal dust (e.g.,5 percent carbaryl) into the nest opening.

Aerosol sprays labeled for wasp or bee control

also are effective. Leave the hole open for a few

days after treatment to allow the bees to contact

and distribute the insecticide throughout the nest

galleries. Then, plug the entrance hole with a

piece of wooden dowel coated with carpenter's

glue, or wood putty. This will protect againstfuture utilization of the old nesting tunnels and

reduce the chances of wood decay.

Although carpenter bees are less aggressive than

wasps, female bees provisioning their nests will

sting. Treatment is best performed at night when

the bees are less active, or while wearing

protective clothing.

Females begin to provision the gallery with

pollen and deposit eggs during May. Bee

development takes 40 to 50 days and 8 to 9 beesare produced in an average gallery. Emerging

bees are not very active, they remain in thetunnel for most of the summer and fall and take

up the bee life in the spring. Some females

live for two years.

DIAGNOSTIC LAB HIGHLIGHTSBy Julie Beale and Paul Bachi

Recent samples in the PDDL have included

Sclerotinia crown/stem rot and Pythium root rot

on alfalfa; white rot (Sclerotium cepivorum) on

garlic; and black root rot and Pythium root roton greenhouse petunia plugs.

On landscape ornamentals, we have seen black

root rot on holly; stippling from previous spider

mite infestation on holly and taxus; Stigmina

needle blight on spruce; and stress symptoms on

white pine.

INSECT TRAP COUNTSApril 1 - 8

Graphs of insect trap counts for the 2011 season areavailable on 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 8 0

Armyworm 194 452

Corn earworm 1 0

European corn

borer

0 0

Southwesterncorn borer

0 0

Fall armyworm 0 0

kentucky pest news april 12, 2011

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