“WHAT’S HAPPENING?”

The University of Tennessee/Agricultural Extension Service

Entomology & Plant Pathology - EPP #60

June 10, 2005

TIMBER ROT IN TOMATOES

by Steve Bost

Timber rot is caused by Sclerotinia sclerotiorum, and is sometimes called Sclerotinia blight or white mold. It is characterized by a tan to light gray stem rot that may occur at the soil line or some distance above it, especially in leaf axils. A white, cottony mycelium may be present in moist conditions. Inside infected stems, mycelium and black, elongate sclerotia resembling mouse droppings are usually found.

Timber rot is an early summer disease, easily discouraged by high temperatures and dry weather. Ascospores become depleted quickly. Fungicide sprays may be applied to protect against ascosporic infections, but will not help against mycelial infections at the soil line. Endura (boscalid) is the most effective tomato fungicide against Sclerotinia. Managing crop growth so that dense canopies are avoided results in microenvironments less favorable for timber rot. A crop rotation away from lettuce, beans, cabbage, and tomatoes is helpful. A biological control called Contans, a preplant granular material, will help reduce the Sclerotinia population.

TOMATO LATE BLIGHT FOUND IN SOUTH CAROLINA

by Steve Bost

Late blight was found in Beaufort County, near the South Carolina coast on Sunday, May 29. With the current increase in shower activity, we may experience some periods of extended cloud cover, which is required for late blight to proliferate.

Growers should keep a general protective fungicide cover on their tomato plants, preferably chlorothalonil. The second choice would be Cabrio, mancozeb or maneb. Chlorothalonil provides excellent protection against late blight and has broad spectrum activity. Where bacterial spot or speck is a concern, mancozeb or maneb may be preferable because of their synergistic activity with copper. There are a number of fungicides rated highly for late blight control, but are more expensive and have severe label limitations in the frequency of use. They should be reserved for higher-risk situations ( late blight present in the field or in the vicinity).

CHOLINESTERASE TESTING REACTION

by Gene Burgess

The Washington State Department of Labor and Industries tested the blood of 580 farm workers who regularly work around pesticides know as organophosphates or carbamates, chiefly used in fruit orchards but also on other crops. The study found 21 percent of them with significant decreases in the enzyme cholinesterase. Nearly 17 percent of the farm workers had a drop greater than 20 percent in enzyme levels after working around the chemicals for more than 50 hours during a 30-day period. Another 4 percent of workers showed a 30 percent drop or greater, triggering their immediate removal from the work site.

A representative for growers and pesticide applicators, was cited as saying that while the study found lower enzyme levels, only one of the workers reported symptoms that could be traced to the pesticides.

SELECTING A PESTICIDE RESPIRATOR

by Gene Burgess

Since April of 1994, pesticide container labels specify the type of respirator required for mixing, handling or application of that particular pesticide. The label contains a NIOSH?MSHA “TC” approved number.

You’ll want to focus on the prefix of this approval number for it indicates the minimum level of respiratory protection that can be used. Under WPS, certain low toxicity pesticides will allow a TC-21C type dust/mist respirator. Certain high toxicity pesticides applied may require a gas mask (TC-14G) or Self-Contained Breathing Apparatus – SCBA (TC-13F). However, most pesticides require a TC-23C type respirator with pesticide (organic vapor) cartridges. Read the pesticide label carefully. If combining pesticides, follow the requirements of the mor toxic label.

PESTICIDE SAFETY EDUCATION PROGRAM (PSEP)

by Gene Burgess

Pesticides are one of the many tools used to manage pests like insects, weeds and diseases. Today there is greater awareness of how important it is to maintain and protect food and other farm products as well as our homes and landscapes. The situation is even more complex due to the growing problem with exotic and invasive species and the threat they pose to our quality of life. Pesticides help us to protect our quality of life such as control of disease-carrying mosquitoes. While pesticides prevent or reduce the damage from pests, there is also potential risk to humans, non-target organisms or the environment if they are used improperly.

The Tennessee Department of Agriculture certifies those who meet the training requirements. Certified applicators are responsible for recertification, every three years in Tennessee. The purpose of recertification is to encourage certified applicators to keep up-to-date on the latest method of pest control, protecting themselves, others and the environment.

Homeowners do not need to be certified to apply general-use pesticides purchased at garden centers, hardware stores or grocery stores. However, these products can also be harmful if used improperly. The PSEP also provides educational sessions for non-certified applicators, such as homeowners. PSEP training sessions also address Integrated Pest Management (IPM) strategies, encouraging the use of alternatives to pesticides when appropriate.

A lot of good training materials are available from PSEP. These manuals should be studied before taking the certification and licensing exams. Check them out at the PSEP website, http://eppserver.ag.utk.edu/psep/psep.htm The Department of Entomology and Plant Pathology offers certification training in CORE, Category 3 and Category 7 on the first Wednesday of each month. We also offer licensing training in HLT, PHMC, GRC and WDO each quarter, before the respective licensing exams are given in Nashville.

Also, one may order study manuals for the pesticide certification and licensing categories and register for certification and licensing seminars at the AgStore, http://ecommerce.cas.utk.edu/agstore

Take advantage of these opportunities.

THRIPS CAUSING AN ITCH

by Karen M. Vail

The Insect: Thrips have been the cause of several cases of itches in the past week or so. Thrips can barely be seen with the naked eye. They are about 1/32 to 3/16 of an inch long and are very slender. On the human body, they may look like a small, moving splinter of wood. Feather-like wings fringed with long hairs are the characteristic that distinguishes this insect from others. Wings are laid back over the body while at rest. The head has compound eyes and less noticeable, simple eyes. In addition, the mouthparts are cone-shaped and are made for rasping and sucking.

The Problem: Most thrips feed on plants which may include landscape plants and grasses found next to homes. Occasionally, these thrips make their way into a home and may bite people causing their skin to itch and a rash to occur, typically, without swelling. Because of their small size, they can often crawl through window screens. They can be brought into homes on cut flowers, other plant material, or clothing or blankets that have been hung outdoors or laid in the grass.

The Solution: Most people that call complaining of itching assume it was caused by no-see-ums. We suggested that they lay flat glue boards around the areas where they were experiencing the itch. Using a dissecting microscope to inspect the glue boards, we identified these fringe-winged insects caught on these boards as thrips.

The interior of the home and the landscape surrounding the home should be inspected to determine the thrips’ host plant. Thrips are serious pests on vegetables (especially onions) and flowers (chrysanthemum, gladiolus, iris). Plant injury caused by thrips rasping the bud, flower and leaf tissues of the host plants, and then sucking the exuding sap, causes distorted and discolored flowers or buds and gray or silvery, speckled areas on the leaves. Interiorscapes, greenhouses and grassy areas, may produce the habitat and food sources for a thrips population. Check for host plants such as potted plants, vegetables, flowers, fruit trees, etc. Thrips may feed between the leaves well down toward the plant base where it is difficult to see. Collect specimens in vials of rubbing alcohol for accurate species identification.

To reduce and eliminate a thrips infestation, vacuum the thrips found indoors. You may want to discard infested indoor plants. Search for infested plants outdoors and treat with insecticides labeled for the host plant. Once the host is located, check the EPP 2005 Insect and Plant Disease Manual or Redbook (http://eppserver/redbook/redbook.htm) for insecticides suggested for thrips control. Active ingredients such as spinosad, azadirachtin and others can be effective against thrips on greenhouse-grown flowers. Outdoors, spinosad (available to the general public as Ferti-lome Borer, Bagworm, Leafminer & Tent Caterpillar Spray), cyfluthrin (Bayer Advanced products) or bifenthrin (Talstar products) may provide some relief, but it is difficult to control thrips in the outdoor landscape when there are so many potential host plants. Remember to always check the label to ensure the plant or site to be treated is listed.

Modified from: Grass Thrips. HYG-2156-94 by William F. Lyon. Ohio State Cooperative Extension service.

Occasional invaders by Paul Bello. 1997. Handbook of Pest Control. Eighth edition. Mallis Handbook and Technical Training Company.

Drawing, courtesy: North Carolina Cooperative Extension Service. Insect and Related Pests of
Vegetables.

ORNAMENTAL PEST UPDATE

by Frank A. Hale

Japanese beetle adults have emerged and are aggregating on the foliage of trees to mate. Many people in areas of Middle and probably West Tennessee were caught by surprise last year by the large amount of defoliation (skeletonized leaves) that occurred in the landscape. Protective sprays of carbaryl (Sevin) and pyrethroids such as permethrin, cyfluthrin, lambda-cyhalothrin, deltamethrin, and bifenthrin can also be used starting now to prevent this damage. Imidacloprid insecticide products work best when applied as a soil drench (Merit 75 WP, Merit 2F, Marathon 60 WP, Marathon II, Discus [imidacloprid plus cyfluthrin], Bayer Advanced Garden Tree & Shrub Insect Control) well before the beetles emerge from the ground and start feeding. Tree injection products with imidacloprid as the active ingredient could be used now but will take time to get up into larger trees.

Bagworms should have all emerged so now is the time to control them. They only have one generation per year and they are easier to control when they are small. Bacillus thuringiensis (Bt.) products can be used to control newly hatched bagworms (when the cone-shaped bags are only 1/8 inch long) while providing safety to the beneficial arthropods in the landscape. Spinosad (Conserve SC, ferti-lome Borer, Bagworm, Leafminer & Tent Caterpillar Spray) are good choices because these insecticides are also easy on the beneficials. Acephate (Orthene), carbaryl, trichlorfon (Dylox) and the many pyrethroids labeled for use on ornamentals can also be used to control bagworms. Control them now and prevent the feeding damage that can be severe in July and August.

FIELD CROP UPDATE

by Russ Patrick

Wheat:

Storing wheat is a tedious venture because it is impossible to control all the insects in the bin. One of the first things to remember is to clean out the bin before you add new grain. Otherwise you will start with an infestation. To control previous infestation, in a 5,000 bushel bin, I would use at least a 5 gallon mixture of Tempo and water. Spray down the walls, sides, around the outside perimeter of the bin as well.

By using one of the "on grain" insecticides you may delay possible invasion of stored grain insects. Last year people had success with a product called Storcide. I understand now that Storcide 2 will be available, hopefully it will work even better.

Keeping the bins cooled down is essential to reducing insect problems. Aeration is another one of the most important things you can do to reduce damage from insects. On cooler days during the summer put the air to it. You will also prevent and potential mold problems from corn with a high percent of moisture.

Disclaimer Statement

Pesticides recommended in this publication were registered for the prescribed uses when printed. Pesticide regulations

are continuously reviewed. Should registration or a recommended pesticide be canceled, it would

no longer be recommended by the University of Tennessee.

Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the

product to the exclusion of others that may be of similar, suitable composition, nor does it guarantee or

warrant the standard of the product.

Precautionary Statement

To protect people and the environment, pesticides should be used safely. This is everyone’s responsibility,

especially the user. Read and follow label directions carefully before you mix, apply store or dispose of a pesticide. According to laws regulating pesticides, they must be used only as directed by the label.

Persons who do not obey the law will be subject to penalties.

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