A new, simple, inexpensive applicator may bring back the days of crop dusting instead of spraying. ARS scientists have patented an over-the-row dust applicator to deliver crop pesticides, growth promoters and regulators, fertilizers and biocontrol agents in powdered form. The apparatus is ideal for grapes and tree fruits, and is expected to be excellent for cotton. Dusting crops reduces the amount of chemicals needed, improves the coverage of plant surfaces, and reduces soil, air, and water contamination. The new applicator will allow the use of lighter equipment that reduces soil compaction, eliminating the need for water. (PATENT 5,228,621)
Appalachian Fruit Research Station, Kearneysville, WV
Charles L. Wilson/Michael E. Wisniewski, (304) 725-345

Traps nabbed 50 percent more boll weevils when natural cotton chemicals were added. ARS scientists added the chemicals, called volatiles, to pheromone-based traps in field studies. The outdoor tests were a follow-up to lab studies showing that volatiles bolster a weevil's response to the pheromone. The pheromone itself is a natural chemical that weevils release to attract mates and signal the presence of cotton plants. ARS is patenting the volatiles, which may also help control southern pine beetles, a forest pest, and beet armyworms, a crop pest. (PATENT APPLICATION 08/015,260)
Boll Weevil Research, Mississippi State, MS
Joseph C. Dickens, (601) 323-2230

A device that looks much like a hand-held garlic press could help farmers put the squeeze on elusive crop pests by revealing the efficiency of aerial pesticide spraying. Pests such as whiteflies like to hide on the bottom surface of crop leaves, where it's difficult for sprays to reach. Researchers developed the device, the dual-sided leaf washer, to quickly determine in the field whether pesticides are going where they're needed. A plant leaf is clamped between two heavy plastic discs and solvent is squirted through plastic tubes onto either side of the leaf. Plastic syringes draw off the rinsing solvent--now also containing pesticide residues washed from each leaf surface--into individual containers. The scientists can measure the amount of pesticide on each side of the leaf. Users can collect samples at a rate of one leaf per minute. The device will work on any leaf with a diameter of at least two inches, such as cotton, cantaloupe, cucumbers, corn and eggplant. (PATENT APPLICATION 08/303,808)
Aerial Application Research, College Station, TX
James B. Carlton, (409) 260-9351

Three rice fungicides can inhibit production of aflatoxin, lab tests have shown. Aflatoxins are natural toxins that can be carcinogenic to humans and animals. In corn and cottonseed, the toxins are produced mainly by the fungus Aspergillus flavus. ARS scientists grew two strains of A. flavus in cultures containing the compounds pentaclorobenzyl alcohol (PCBA), fthalide or pyroquilon. All three strongly inhibited the accumulation of all aflatoxins without affecting fungal growth. PCBA had the greatest effect. Pyroquilon and fthalide already are used to prevent rice blast disease, caused by a different fungus. Next step: determining whether the compounds work as well in crops in the field.
Cotton Pathology Research, College Station, TX

Michael H. Wheeler, (409) 260-9516

A genetic test for plant pathogens called MLOs can, in a few days, "finger" insects carrying the disease. MLOs--mycoplasmalike organisms--damage fruits, vegetables and ornamental crops. A quick sampling of insects taken from a field would give farmers an early warning so they could nip the disease before it spreads throughout a crop. ARS scientists, who developed the original MLO test, have the new version in its experimental stage. Once perfected, the test can be used by diagnostic companies and extension offices. It identifies MLO-carrying insects more quickly and reliably than standard greenhouse tests that now take a week, month or even a year. Key to the test is a gene-multiplying technique called polymerase chain reaction, or PCR. Researchers use PCR to make millions of copies of specific MLO gene fragments--if any are present in insect test samples. That generates enough MLO genetic material to make a diagnosis.
Molecular Plant Pathology Lab, Beltsville, MD
Robert E. Davis, (301) 504-5745

Using pine or Eucalyptus trees as windbreaks bordering orange and grapefruit groves can reduce citrus canker to very low levels. This results in significant savings in the cost of disease control for growers. Caused by a bacterium, citrus canker can strip citrus trees of their leaves and cause fruit blemishes, resulting in yield and quality losses. ARS scientists tested windbreaks in Argentina where citrus canker is common. They found that the tree barriers--by reducing the speed of wind-carried rain water that carries the bacterium--were more effective than bacterial sprays in reducing the disease's occurrence and spread. Bacterial sprays are costly and have been only marginally effective.
U.S. Horticultural Research Laboratory, Orlando, FL
T.R. Gottwald, (407) 897-7347

Overfertilizing poinsettia plants encourages attack by the silverleaf whitefly--formerly known as biotype B sweetpotato whitefly--one of the ornamental's worst pests. To protect poisettias, researchers also advise growers to use the calcium nitrate form of fertilizer. It apparently makes poinsettias less attractive to the pest than ammonium nitrate, the most common form of nitrogen fertilizer. Whiteflies destroy plants by feeding on their juices. ARS scientists found more pests on fertilized poinsettia plants than on unfertilized plants. Researchers found female whiteflies laid more eggs on leaves of plants fertilized with ammonium nitrate, compared with those unfertilized or fertilized with calcium nitrate. Last year, the wholesale value of U.S. poinsettias exceeded $170 million.
Florist and Nursery Crops Unit, Washington, DC
Jo Ann Bentz, (301) 504-8260

Last Updated: December 13, 1996
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