Kentucky Pest News Newsletter

HIGHLIGHTS IN THIS ISSUE

Number 1035__________Aug 30, 2004

TOBACCO
SORGHUM
SOYBEAN
WHEAT
SHADE TREES AND ORNAMENTALS
HOUSEHOLD
DIAGNOSTIC LAB HIGHLIGHTS
IPM TRAP COUNTS


Ky Blue Mold

TOBACCO



ELIMINATING BUMBLE BEES IN BARNS
By Lee Townsend

Bumblebee Barns provide great nesting sites for bumble bees. These fuzzy yellow and black bees nest in abandoned rodent burrows or most any dark cavity that contains fibrous material. This late in the year the colony may be home for 50-400 bees. Typically, some stay around the entry way as guards and will angrily attack intruders. Bumble bee stingers are smooth so a single bee can sting many times. While best left alone, sometimes it becomes necessary to eliminate nests before housing tobacco or storing other crops or equipment.

First, find nest entrances by watching the bees come and go. This is where the control application should be made. Treat the opening at night using low background light. Dust formulations tend to be the most effective means of delivering the insecticide. A duster, such as an old squeeze catsup or mustard container, can be use to puff the insecticide into the entry way. Dust the entry area and tunnel liberally so that the bees will pick up the dust as they enter and leave the nest. Wearing a bee veil or some other type of face protection is highly recommended. Also, an aerosol container of wasp and hornet spray should be handy to subdue any bees that may be stirred up by the activity. Be patient, it probably will take several days to see a reduction in activity.

It may be tempting to pour diesel fuel into the hole. This may kill a few unlucky bees that are covered directly but most of the liquid will be absorbed into the ground with no residual effect. Use of gasoline can convert the barn into a carburetor chamber with disastrous results.

For the latest blue mold status and other tobacco disease information, check the KY Blue Mold Warning System online.
Blue Moldhttp://www.uky.edu/Agriculture/kpn/kyblue/kyblue.htm

For more information about tobacco pests, visit "Insect Management Recommendations".



Soybeans

SOYBEAN



SOYBEAN APHIDS STILL ACTIVE
By Doug Johnson

SB aphid It is getting toward the end of the season and early beans are turning yellow and defoliating. However, one does not have to drive far to see some very young beans.

Whether it is late planting, replanting or "setting and waiting" during our July "drought" makes no difference. If you have beans that have not yet bloomed or are in bloom you need to check them for soybean aphids.

The aphid is common but not abundant in most areas.

They are not so common as to be striking to the casual observer, but if the plants are green, it doesn't take too long to find a few of them. These are small insects that are easily overlooked, until massive populations are present. By then the damage may be done.

Most plantings are far beyond the stage that is most susceptible to soybean aphid damage. However, very late beans are still at risk. I think that it is unlikely that there will be a widespread problem, but if you have late beans then a trip to the field to check on them is certainly a good idea.

Current data suggest that soybeans are most susceptible to yield loss during the R1 to R4 stages. If you have plants that are just beginning to bloom, in full bloom or early pod fill they are still at risk from this pest. At this plant stage an aphid population of 250 aphids per plant will warrant a control.

For an overview of this insect in Kentucky take a look at The IPM Web page at: http://www.uky.edu/Agriculture/IPM/ipm.htm then "click" on the soybean aphid near the bottom of the page.

For more information about soybean pests, visit "Insect Management Recommendations".


Wheat

WHEAT


 


PRE-SEASON CONSIDERATIONS FOR INSECT CONTROL IN WHEAT
By Doug Johnson

Wheat
It is time again to begin thinking about insect control in our wheat crop. In many cases you have probably already given consideration to such items as variety selection, seeding rates and tillage. Certainly pest control should also have your attention as decisions made before planting will have an effect on insect populations for the entire wheat growing season.

Without doubt, one of the most important decisions you will make is planting date. This choice will shape all of the pest decisions you will have to make in the fall and may even impact your spring season. Do not treat it lightly. Planting date will directly affect all three of Kentucky's possible fall pests.

Another pre-season decision will be whether or not to use an insecticide seed treatment. This technique, when used in Kentucky wheat culture, is aimed primarily at controlling the aphids that spread the Barley yellow dwarf virus. At present, these treatments must be applied by commercial seed treaters and the time needed to get this done requires booking seed well in advance of planting.

Fall Armyworm - an unusual, but certainly possible, fall foliage feeder on small grains. Fall armyworm (FAW) is already in the area having lived on corn, sorghum and wild grass hosts since about July. Early planting and a late mild fall will favor this pest. FAW could survive until heavy frost. In general, FAW will eat off the above ground portions of the plant and do little lasting damage. There are no thresholds for control of this pest in small grains. Control should not be difficult, but the decision as to whether or not to make a spray is not at all clear. One thing is for sure, most plants will come back even if all the above ground parts are eaten, so producers are advised not to replant without considerable evidence that the original stand is damaged. Replanting usually results in a "double stand", which in turn, results in severe lodging and other problems.

Hessian Fly - has not traditionally been considered a major pest of Kentucky's small grains. Unfortunately, that may be because we have never looked very hard. To get a better idea of how this insect affects Kentucky's crops see Entfact-101. However, from an immediate practical standpoint, there are only a few things you can do to manage for this insect. Again, the most important is planting date. This is the insect for which the term "Fly Free Date" was coined. In general, crops planted after this date will not be infested with Hessian fly. In Kentucky, the date varies from about Oct 10 in the northern wheat growing counties to Oct 15 in the southern tier of counties (See Entfact-101, ENT-56). In addition, it is important to pay strict attention to all agronomic practices and variety selection that will produce strong, vigorous plants that stand well. Though resistant varieties will help, (and should be used if other plant characteristics are appropriate for your management plan) the populations of this pest found in Kentucky are able to break all the deployed resistance.

Aphid Complex and Barley Yellow Dwarf - This is, without doubt, the most contentious problem we have to face. Though it is important to remember that the insect feeding itself is unimportant, the transfer of Barley Yellow Dwarf Virus (BYDV) is extremely important. Once again, you have a very good management tool for avoiding the problem -- planting date. Though it is not absolute, as one plants later, the chances of a problem with transmittal of BYDV decrease. Though there is no definable calendar date for avoiding BYDV, the "Hessian Fly Free" makes a good compromise.

Beyond planting date, the fall weather will be the next most important factor in decisions concerning aphids and BYDV. Certainly, we would like to see the fall cool down to reduce the survival of incoming aphids and to slow the movement of aphids in the field. Producers/consultants should be on the lookout for aphids, especially in the first 30 days after planting. The earlier aphids appear the more problem one would expect from BYDV. So, if you need control, how do you obtain it? Some producers are using the seed treatment technology to get a jump on the aphids. This has both advantages and disadvantages.

Disadvantages:

Advantages:

If you choose the wait and see position of using a foliar applied rescue application, you are likely to hear the continuing discussion about how many aphids should be present before there is a need to spray. In the past, scientific literature has suggested about 10 aphids per row foot. Many consultants think that 5 aphids per row foot is more appropriate. Additionally, there is some new research from Georgia that suggest (at least in the deep south, in the first 30 days post plant) that three aphids per row foot is the appropriate number. At present we recommend a threshold of: 3 aphids per row foot for the first thirty days post emergence; 6 aphids per row foot for the 2nd thirty days post emergence; then 10 aphids per row foot until temperatures are generally below 48 F.

Variation from poor sampling, or too little sampling, will completely wipe out any precision gained by having a more refined threshold, - AND - this will still not address whether or not the aphids are carrying the virus!

Fall control of aphids designed for control of BYDV will remain a difficult decision for a while yet. However, I think the following factors still deserve your consideration.

Factors to consider when deciding on foliar insecticide intervention.

1. Factors that do not favor attempting insecticidal control of aphids.

2. Factors that favor attempting insecticidal control of aphids.

Likely Outcomes -

1. In epidemic years, sprays may pay for themselves, but will not likely protect the maximum yield potential.

2. In years of slight BYD, sprays will cost the producer.

3. In intermediate years, sprays will pay for themselves and a larger percentage of the potential yield will be protected.

4. Planting after the Hessian Fly free date is worth one spray, possibly two.

5. There are some years where the effect of spring infection/movement is economically important. However, fall infection appears to be far more important. With both the seed treatment and fall foliar application, it is possible that a late winter early spring application will be needed. This is likely to depend upon how "late" warm fall weather extends and the "mildness" of the winter.

6. In the long term, obtaining the ability to predict or at least estimate disease severity, will be the most important management tool for producers.

You might want to review a previous article (listed below) that illustrates the difference between incidence of symptoms and yield protection and the cost / benefit of yield protection. Johnson, D. and L. Townsend. Can Aphid Control Reduce Barley Yellow Dwarf Incidence In Wheat? A case study (Caldwell Co., KY 1998-99) Kentucky Pest News No. 862, 13 Sept. 1999. http://www.uky.edu/Agriculture/kpn/kpn_99/pi990913.htm

REFERENCES:

Insecticide Recommendations for Small Grains. ENT-47. http://www.uky.edu/Agriculture/PAT/recs/rechome.htm

Hessian Fly in Kentucky. Entfact-101. http://www.uky.edu/Agriculture/Entomology/entfacts/pdfs/entfa101.pdf

Aphids and Barley Yellow Dwarf (BYD) in Kentucky Grown Wheat. Entfact-121. http://www.uky.edu/Agriculture/Entomology/entfacts/pdfs/entfa121.pdf

IPM- 4 Kentucky Integrated Crop Management Manual for Field Crops - Small Grains http://www.uky.edu/Agriculture/IPM/manuals.htm


Grain Sorghum

SORGHUM



GRAIN SORGHUM INSECTS IN SEPTEMBER?
By Doug Johnson

Grain sorghum is beginning to find a larger place in our grain production system. One reason is the lack of insect pests when the crop is grown during its optimum planting time. However, like any of our other grain crops, when grain sorghum is planted out of its optimum time period it is subject to insect infestation. Grain sorghum can be planted too early and too late. Obviously, at this time of year we are interested in the too late part.

If your grain sorghum crop is already in the hard dough stage you are probably by most of the problems. However, if your crop is still the milk to soft dough stages, you need to watch out for the "head worm" complex. This is a group of caterpillars that will feed in the heads as long as the grain is soft enough for them to eat.

The likely first "head worm" will be the corn earworm, aka soybean pod worm. As corn and soybean fields begin to mature, the adult moths begin Young (typically double crop timed) grain sorghum can be just the right food source.

The corn earworm larvae vary in color from light green to black, with lighter stripes running the length of the body. When larval development is complete earworms may reach 1 " in length. Larvae have three pair of true legs near the head, four pair of fleshy legs near the center of the body and one pair of fleshy legs near the rear end. These larvae may be confused with fall armyworm; however, earworms do not have an inverted "Y" on their heads. (Corn earworms and fall armyworms may be found in mixed populations. If both species are feeding on the heads, it makes little difference which species they are.) Both species are "naked" worms in that they have no, or few, obvious hairs.

The later arriving pest and the most typical one for September is the sorghum webworm. In addition to feeding on the grain, this pest makes a mess of the head. They spin a small web which tends to hold moisture and to collect their feces, so the whole area is contaminated. Sorghum webworm is smaller than the corn earworm (or fall armyworm), reaching " in length when mature. Webworms are green and "bristly".

Neither of these pests (and they may occur together) is hard to find or count on heads. To scout, examine twenty heads in each location for the presence of the worms. If you find an average of two worms or more per head of either or both species then you need to consider an insecticidal control.

If insecticidal control is warranted you may check in ENT- 24, Insecticide Recommendations for Grain Sorghum (Milo), to find products and use suggestions. This publication may be found on the web at: http://www.uky.edu/Agriculture/PAT/recs/rechome. htm or in print from your County Extension office.

You can obtain a grain sorghum scouting manual by going to the IPM Web page at: http://www.uky.edu/Agriculture/IPM/ipm.htm then "click" on "Manuals & FactSheets".


Maple

SHADE TREES AND ORNAMENTALS



DODDER, A PARASITIC PLANT, INVADES FLOWER BEDS
By John Hartman

Dodder, a parasitic plant, has been the subject of recent calls and observations of infested flower beds in Kentucky. The most common query is: "What is that yellow-orange, spaghetti-like vine doing in my petunias?" To those familiar with this noxious parasite, dodder is easily recognized by the thin strands of yellow-orange leafless vines that become entangled and entwined with garden plants. The dodder plant is also called love-vine, gold-thread, strangle-weed, hair-weed, witches' shoelaces, devil's-guts, devil's-ringlet, devil's-hair, and hell-bine. Common dodder seen in the garden is a species of Cuscuta, a member of the morning glory family. Dodder often thrives in wet, marshy areas and has been favored in Kentucky gardens by the wet growing seasons of the past two years.

Dodder's damage.
Dodder, with only strand-like pale yellow stems and no leaves of its own, lacks sufficient chlorophyll to survive and must obtain its nutrition from other plants. This parasitic habit reduces the growth and vigor of the plants being parasitized, though rarely killing them. In addition, a thick growth of dodder may form a mat over the garden plants, blocking sunlight to them, further reducing their well-being.

Dodder's life.
Dodder seeds typically germinate in garden soil in the presence of a suitable host. In the absence of a host plant, the seeds may remain dormant for five years. Dodder seedlings must attach to the host plant within a few days of germinating; if not the seedlings do not survive. The yellow vine-like seedling is sensitive to touch and the growing, groping stem hooks onto the nearest plant and the dodder quickly coils in a counter-clockwise direction about the host leaf or stem. If the host is suitable, the dodder produces root-like branches (haustoria) which penetrate the host plant. Dodder obtains carbohydrates, water, and mineral elements from its host and when the original seedling root system vanishes the parasite loses its connection with the soil and becomes almost totally dependent on its host. Dodder grows aerially from plant to plant in the bed, and can be a parasite of multiple hosts simultaneously. When attached to more than one host plant in the landscape bed, dodder is capable of transmitting certain virus and phytoplasma diseases from one plant to another.

Dodder produces numerous tiny bell-shaped, white or yellowish flowers which bloom from June to October. Dodder fruits are small (about 1/8 inch wide) with papery walls and contain one to four seeds. The fruits break easily, spilling the seeds where they can grow the next year. The seeds have a hard seed coat which allows them to survive for many years. Dodder seeds can be spread by irrigation water, movement of soil, and by contaminated seeds of crop plants. Dodder is killed by freezing temperatures and it survives as an annual plant which grows each year from seeds dropped from last year's plants. Sometimes, if the host plant and the dodder survive winter, dodder haustoria can stay alive inside the host and can emerge again in spring already attached to its host.

Dodder's hosts.
Most dodder species grow on several different types of plants, however some species of dodder are host-specific. In flower gardens, dodder may be found on chrysanthemum, dahlia, English ivy, geranium, goldenrod, helenium, petunia, snapdragon, and trumpet-vine. In cropping fields, dodder attacks alfalfa, clover, flax, lespedeza, potatoes, tobacco, tomatoes, and small fruits such as blackberry and blueberry. Other hosts include lizard's tail, spotted jewelweed, Virginia creeper and wild onion, especially along roadsides and in fields and thickets. The different species of dodder are difficult to distinguish from one another and they may have different host ranges.

Dodder management.
Once established, dodder is almost impossible to eradicate.


House

HOUSEHOLD



DANGER ZONE - ELIMINATING WASP AND HORNET NESTS
By Mike Potter

Wasp stings are a serious health threat to humans and animals. Many people in the United States die each year from allergic reactions to the venom of these insects. Paper wasps, hornets and yellowjackets are more dangerous and unpredictable than honeybees. Workers foraging away from the nest are seldom aggressive, but nests should be eliminated with great care and in a specific manner. "Folk" remedies such as dousing nests with gasoline or a garden hose seldom work and can result in multiple stings.

Paper Wasps
Paper wasp Paper wasps (as well as hornets and yellowjackets) construct nests of a paper-like material containing finely chewed wood fragments and salivary secretions. Paper wasps typically build their umbrella- shaped nests in protected locations, such as under eaves and ledges or in attics and outbuildings. Nests also may be located behind shutters, or inside exterior light fixtures, gas grills and mailboxes. Most paper wasps are brownish or rust-colored, although one variety, the European paper wasp, has yellow and black markings much like a yellowjacket. Paper wasps have a "waist" that is very thin, however, which distinguishes them from hornets and yellowjackets.

Paper wasps are not very aggressive, but stings can occur when householders inadvertently disturb nests that are hidden. If the nest is accessible, it can be eliminated rather easily with a wasp and hornet spray sold at most retail stores. One advantage of these formulations is that they can be sprayed as far as 20 feet. Although it's best to treat all wasp nests at night, paper wasps can be eliminated during the daytime provided you do not stand directly below the nest during treatment. Most wasp aerosol sprays cause insects to drop instantly. Standing directly under a nest increases the risk of being stung. After treatment, wait a day to ensure that the colony is destroyed; then scrape or knock down the nest.

Hornets
Hornet nest Hornets are far more difficult and dangerous to control than paper wasps. The nests resemble a large, gray, bloated football, which typically is attached to a tree, bush or side of a building. Oftentimes the nest is concealed among branches, especially in densely canopied trees such as Bradford pear. Hornet nests may contain thousands of wasps that are extremely aggressive when disturbed. The nests often are located out of reach and elimination is best accomplished by a professional pest control firm.

Treat hornet nests at night when most insects are within the nest and less active (follow night treatment precautions discussed below for yellowjackets). A full wasp suit, sealed at the wrists, ankles and collar, is recommended. Apply an aerosol-type wasp and hornet spray or dust formulation (e.g., Sevin, Drione, DeltaDust) directly into the nest opening. Hornet nests generally have a single opening, usually toward the bottom, where the wasps enter and exit. It is crucial that the paper envelope of the nest not be broken during treatment or the irritated wasps will scatter in all directions, causing even greater problems. Following treatment, wait at least 2- 3 days before removing the nest to ensure that all of the wasps are killed. If hornets continue to be seen, the application may need to be repeated.

If the nest is located away from frequently used areas, another option is to wait and do nothing. In Kentucky, wasp, hornet, yellowjacket, and bumblebee colonies die off naturally after the weather turns cold, and the paper carton disintegrates over the winter months.

Yellowjackets
Yellow jacket Yellowjackets are probably the most dangerous stinging insects in the United States. They tend to be unpredictable and usually sting if the nest is disturbed. Yellowjacket nests are often located underground in old animal burrows (e.g., chipmunks), or beneath rocks or landscape timbers. They also build nests in walls, attics, crawlspaces, and behind exterior siding of buildings.

If the nest can be located, it often can be eliminated by applying an aerosol-type wasp and hornet spray into the opening. Insecticide dust formulations containing Sevin (sold in lawn and garden shops), DeltaDust, or Drione, are especially effective but require a hand duster to dispense several puffs of the dust into the nest opening. In lieu of a commercial duster, a workable alternative is to use a dry, empty liquid detergent bottle filled with an inch or so of dust. A few pebbles or marbles added to the bottom prevents the dust from caking, and the bottle should be shaken before dispensing. (Remember to dispose of the bottle after use, or store it away from children and pets). Dusts tend to be more effective than aerosols when the nest itself is located some distance from the entrance hole - as often occurs when yellowjackets construct nests behind exterior siding or deep within abandoned animal burrows. Insecticide dust blown into the opening penetrates farther than sprays, and the workers transport it throughout the nest.

Ideally, treatment should be performed at night, when most of the yellowjackets are in the nest and less active. Pinpoint the nest opening during the daytime, so you will remember where to direct your treatment after dark. Approach the nest slowly and do not shine the beam of your flashlight directly into the nest entrance as this may startle the wasps and cause them to fly toward the light. Instead, cast the beam to the side to illuminate the nest indirectly. If possible, place the light on the ground rather than in your hand.

When contemplating extermination of a yellowjacket or hornet nest, clients should be informed that they are entering a DANGER ZONE - there is no pest control scenario more frightening than a 'blown' wasp or hornet treatment. It is often prudent to refer homeowners to a professional, especially when access to the nest requires a ladder or is difficult.

Wasp, hornet and yellowjacket stings can be life threatening to persons who are allergic to the venom. People who develop hives, dizziness, breathing or swallowing difficulty, wheezing, or similar symptoms of allergic reaction should seek medical attention immediately. Itching, pain, and localized swelling can be reduced with antihistamines and an ice pack.


Microscope

DIAGNOSTIC LAB HIGHLIGHTS


DIAGNOSTIC LAB - HIGHLIGHTS
By Julie Beale and Paul Bachi

Over the past two weeks we have received diagnostic samples of Diplodia ear rot on field corn; sudden death syndrome, charcoal rot, soybean cyst nematode, downy mildew, frogeye leaf spot, Cercospora leaf blight, brown spot (Septoria), Phytophthora wilt, and potassium deficiency on soybean; black shank, blue mold, frogeye leaf spot, target spot, angular leaf spot, brown spot (Alternaria), Fusarium stem canker, potato virus Y, and manganese toxicity on tobacco.

On fruits and vegetables, we have diagnosed double blossom on blackberry; cedar-apple rust and scab on apple; thread blight on pear; anthracnose on bean; virus complex on squash; angular leaf spot and downy mildew on pumpkin; Septoria leaf spot, bacterial canker and early blight on tomato; and gummy stem blight on watermelon.

On ornamentals and turf, we have seen Pythium and Rhizoctonia root rots on vinca; powdery mildew on lilac; black root rot on holly; Verticillium wilt on magnolia; bacterial scorch on oak, maple and sweetgum; Actinopelte and Elsinoe leaf spots and iron deficiency on oak; Cercospora leaf spot on willow; Phomopsis canker on kerria; summer patch on bluegrass, and anthracnose basal rot on bentgrass.


Scout Cat

IPM TRAP COUNTS:


By Patty Lucas, University of Kentucky Research Center

UKREC-Princeton, KY, August 13 - 20, 2004
Black Cutworm 1
True Armyworm 4
Corn Earworm 15
European Corn Borer 2
Southwestern Corn Borer 14
Fall Armyworm 42

UKREC-Princeton, KY, August 20 - 27, 2004
Black Cutworm 1
True Armyworm 6
Corn Earworm 32
European Corn Borer 0
Southwestern Corn Borer 16
Fall Armyworm 4

To view previous trap counts for Fulton County, Kentucky go to - http://ces.ca.uky.edu/fulton/anr/ and click on "Insect Trap Counts".

For information on trap counts in southern Illinois visit the Hines Report at - http://www.ipm.uiuc.edu/pubs/hines_report/index.html. The Hines Report is posted weekly by Ron Hines, Senior Research Specialist, at the University of Illinois Dixon Springs Agricultural Center


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.


Lee Townsend
Extension Entomologist

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