“WHAT’S HAPPENING?”

The University of Tennessee Extension Service

Entomology & Plant Pathology - EPP #60

July 1, 2005

SOYBEAN RUST UPDATE

by Beth Long

From the USDA Soybean Rust National Map Commentary (updated: 06/30/05) located at: http://www.sbrusa.net/

Three counties have now reported soybean rust on soybeans. They are Baldwin County in Alabama, Marion County in Florida (6/29) and Seminole County in Georgia. The Alabama and Florida finds were in sentinel sites on soybean, while the Georgia find was on volunteer soybeans which have since been destroyed. Six counties in Florida have now reported soybean rust on kudzu. The latest find is in Leon County in Northern Florida.

Intensive scouting is continuing throughout eastern North America from the Gulf coast to southern Ontario wherever soybean is grown with no new finds. Although many areas in the southeast U.S. have been wet this past month, which encourages disease spread, air temperatures are now climbing to levels that are less favorable for spore production. However, if the winds and rain associated with tropical storm Arlene were involved in transporting soybean rust spores from known U.S. sources, and potentially other unknown sources in the U.S. and the Caribbean basin, new soybean rust infections could soon be observed.

To date all Tennessee sentinel plot samples and spore traps have been negative for soybean rust.

The North Carolina State University Soybean Rust forecast shows that there is a low risk for spores being blown into the Tennessee area over the next several days.

Updated information can be found at:

http://www.ces.ncsu.edu/depts/pp/soybeanrust/forecasts/s050629.php?month=06&year=05

TOBACCO INSECT REPORT

by Gene Burgess

Green County (6-22-05):

Only one flea beetle was been reported in the tobacco test plots.

Carter County (6-24-05):

A very small number of flea beetles, one to three in five plants, were reported in the Platinum, Orthene and Admire plots. No other insects, diseases or weeds were reported.

Loudon County (6-28-05)

One flea beetle was found on several plants. Black shank and sun scald was found.

Meigs County (2-27-05)

An average of one flea beetle per plant was found. A small amount of angular leaf spot was reported on most plants scouted. A few weeds were present.

Farmers need to be scouting their tobacco fields once a week for cutworms, wireworms and flea beetles. Do a random check of five consecutive plants in four to six locations in the field. Then average the results. Check in SP91, Tobacco Pest Control and see if the insects have reached economic threshold levels and what insecticide to use if necessary.

NEW INSECTICIDES AND MITICIDES FOR ORNAMENTAL CROPS

by Frank A. Hale

There are several new products available for ornamentals. Flonicamid (Aria 50 WDG) has a new mode of action that inhibits insect feeding within one hour of treatment, eliminating the pest in 3-5 days. The mode of action grouping for Aria is called the selective feeding blockers. It is labeled for control of aphids, thrips, whiteflies (suppression only of silverleaf whitefly), and mealybugs in greenhouses on ornamental crops. Another selective feeding blocker that has been around some time, is Endeavor. It was given “Reduced Risk” status by the EPA and exhibits safety to beneficial insects. Endeavor is labeled for control of aphids and whiteflies and has translaminar activity, which allows it to move from one side of the leaf (sprayed side) to the other.

Insect growth regulators (IGRs) target immature insects and mites. Some IGRs can also make the adults sterile. The chiten synthesis inhibitors prevent the formation of chiten which is needed for the formation of the insect or mite exoskeleton. When treated with this type IGR, the insect or mite dies while trying to molt to the next stage. Diflubenzuron is an older compound (Dimilin) that is still effective that is now available for greenhouse use as Adept. There are three newer IGR compounds (Talus, TetraSan and Pedestal) available for ornamental use.

Buprofezin (Talus) is labeled for control of the nymph stages of whiteflies, scales (soft, armored, margarodid [such as cottony cushion scale]), mealybugs, planthoppers, and leafhoppers. It also suppresses egg-laying and causes egg sterility in treated adult insects.

Etoxazole (TetraSan 5 WDG) is labeled for the control of spider mites in the egg or nymph stage. It can be used on ornamental plants and non-bearing fruit and nut trees indoors (greenhouse, interiorscapes and other listed sites) and outdoors. TetraSan is not intended for indoor or outdoor residential uses. It also exhibits translaminar movement within the leaves. It should not be applied to poinsettias after bract formation.

Novaluron (Pedestal) is labeled for the control of thrips, whiteflies, armyworms and suppression only of leafminers. Pedestal should not be applied on poinsettias.

One mode of action grouping, called oxidative phosphorylation uncouplers, prevent the formation of a critical energy storage molecule, adenosine tri-phosphat (ATP). Chlorfenapyr (Pylon) is the only currently labeled product in this mode of action grouping labeled for use on greenhouse ornamentals. Pylon is labeled for control of fungus gnats, foliar nematodes, caterpillars, spider mites, broad mite, rust mites and citrus rust mite. Pylon is not ovicidal but does exhibit translaminar movement in the leaf.

TOBACCO BLUE MOLD

by Darrell Hensley

Tobacco blue mold was reported and confirmed in Elizabethtown, KY on 6/29/05. Gary Palmer, Kentucky's Extension Agronomist confirmed blue mold west of Elizabethtown, KY (West-Central, KY) on Wednesday. Dr. Palmer indicated that it appeared to be in it's second cycle and was fairly extensive considering the dry weather in the area. New leasions were pinpoint spore strikes, but some new more active blue mold was present and sporulating.

Dithane DF, Acrobat MZ, Acrobat 50WP and Actigard are labeled for blue mold control. Please read the label prior to use of any products.

If blue mold is present in the field, use protectant fungicides; Dithane DF, Acrobat MZ or Dithane DF mixed with Acrobat 50WP and use a hollow cone nozzle directed over the row if one foot in height or shorter. Drop nozzles will be needed on larger plants to obtain thorough leaf coverage, again use hollow cone nozzles.

Actigard has a different mode of action than mancozeb or dimethomorph and may be applied to tobacco 18 inches in height or larger, however it must be applied five days prior to the onset of infection to achieve effective control. Actigard does have advantages, it may be applied using flat fan nozzles and coverage is not as critical as protectant type fungicides (Dithane or Acrobat).

Note: if you intend to use Acrobat 50WP, you must also use Dithane DF with the product to achieve effective control.

TOMATO SPOTTED WILT VIRUS IN TOMATO

by Steve Bost

Tomato spotted wilt virus (TSWV) has been widespread across the state this year. If a gardener calls the Extension office regarding a blight in the top of a tomato plant, it is probably TSWV. Symptoms can vary, but are most often a generalized necrosis of young leaves. Purple, bronze, or necrotic specks, spots, and rings can occur on the leaves or stems (http://eppftpserver.ag.utk.edu/profiles/disease/vegetable/TSWV.htm).

Leaf blades are pale and growth is stunted. Fruit on affected plants may have roughened skin or yellow rings.

Naturally, growers want to know what to do about such a drastic disease. Realistically, there is little that can be done to effectively stop the spread in tomatoes. Spread may stop on its own if the weather is hot and dry, because of the effect of such weather on the thrips vector. Otherwise, spread can continue on tomatoes throughout the growing season. Insecticides with thrips activity can slow the spread if applied early and often. For home gardeners, likely candidates would be pyrethroid materials such as Bug-Be-Gone and spinosads such

as Ferti-Lome’s Borer, Bagworm, Leafminer, & Tent Caterpillar Spray. Insecticides for commercial growers would be Lannate, SpinTor, and Monitor. ‘Amelia’ and ‘BHN 444' are resistant varieties.

TOMATO SPOTTED WILT VIRUS IN TOBACCO

by Steve Bost

TSWV is present in tobacco as well as tomato (see related article). Look for scattered plants with yellow leaves and necrotic lines and rings. Leaf tissue becomes necrotic, and contrasting white to gray spots are often scattered through the necrotic leaf tissue. Often, only a part of a leaf is affected. Plants are stunted. Occasionally, when the thrips vector inserts the virus in a lower leaf so that the bud is not affected, the plant develops a smooth, canary yellow leaf color lacking the necrosis. This type of infection can resemble black shank, and both types of TSWV infection cause a brown discoloration on the lower stalk reminiscent of black shank. However, TSWV-infected plants lack the wilting associated with black shank. Additionally, the brown area on stalks of TSWV-infected plants are rough, with dimples and ridges. This characteristic is extremely useful in confirming a TSWV infection.

Growers who are not accustomed to TSWV are alarmed by the appearance of the plants. However, the incidence of this disease in tobacco fields is typically low and seldom spreads much, if any, from the initial infection level. In the early years of TSWV in Tennessee (late 1980's), heavily-infected fields occasionally occurred, but I have not heard of any lately. Isolated plants lost early in the growing season cause no yield loss, since neighboring plants compensate for their loss. This is fortunate, since there is no effective control for TSWV in burley or dark tobacco.

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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