Insecticide applications on stored wheat can be reduced or eliminated by timely cooling of the grain with automated fans. Computer simulation showed unaerated grain is a prime breeding ground for rusty grain beetles, especially unaerated wheat stored in bins of 10,000 bushels or more. The computer simulation showed an automatic aeration controller could keep insect populations below economically damaging levels without insecticides, even as far south as Oklahoma. Scientists say the automated system could be set to turn on fans whenever air temperature is 18 degrees F lower than grain temperature. The automated system suppresses insects by cooling the grain as soon as possible, and saves electricity and grain weight loss by cooling only when necessary.
Biological Research, Manhattan, KS
Paul W. Flinn, (913) 776-2707, flinn@usgrmrl.ksu.edu

The herbicide chlorsulfuron kills or slows growth of the roots of tall whitetop weeds--something other available herbicides can't do, say ARS scientists. Tall whitetop, also called perennial pepperweed, is an increasing problem in western native hay meadows. The weed is among the five worst noxious weeds in Nevada. Cattle there rely on native grass hay for winter feed. But they won't eat hay dominated by this weed. Several chemicals kill its flowering stalks and leaves, but range managers don't have a tool for killing its roots or slowing their spread. In the first two years of an ARS study, chlorsulfuron controlled the roots. Another advantage: Chlorsulfuron can be applied in the fall, while other popular herbicides such as 2,4-D must be applied in the spring, posing a threat to nesting waterfowl. Scientists suspect tall whitetop is spreading rapidly across the West, though its full extent is unknown. In one part of their study, ARS scientists monitored the weed's spread in 500 acres of privately owned grassland. Once whitetop invaded, it spread from zero to 100 acres in five years.
Ecology of Temperate Desert Rangelands Unit, Reno, NV
James Young, (702) 748-6057

Like the Greek monster Medusa's snaky tresses, "hairs" on plant surfaces can prove deadly to leaf rust spores that attack wheat and rye. Scientists say rust infestation has been reduced up to 27 percent in plants with hairy leaves. When spores of the culprit fungus Puccinia recondita land on leaves, they send out root-like structures called hyphae. These structures search for stomates--openings on the plant leaf surface through which the plant takes in vital carbon dioxide--as vulnerable spots to invade the plant. But if the hyphae can't find its way through the maze of leaf hairs, the spore dies before damage is done. Plant breeders could use this information in developing new crop varieties with built-in protection against rust disease, which costs wheat and rye growers millions of dollars annually in lost yields.
Cereal Rust Laboratory, St. Paul, MN
Dave L. Long, (612) 625-1284, davidl@puccini.crl.umn.edu

A plum called Deep Purple might help almond growers who today can't produce the country's top almond variety--Nonpareil-- because of root-destroying nematodes and soggy soils. Almond trees don't root readily and are susceptible to nematodes. To bypass these problems, almond budwood typically is grafted to botanical relatives such as peach (for well-drained orchards) or plum (for sodden sites). Nonpareil can't be grafted onto certain choice plum rootstocks, but preliminary ARS tests indicate Deep Purple might fit the bill. For the experiments, ARS scientists grafted budwood of several almond relatives onto Deep Purple rootstock. The grafts remain strong four years later. Also, Deep Purple outperformed other rootstocks in tolerating bacterial canker and two kinds of nematodes. A hardy plum introduced by the University of Minnesota in 1965, Deep Purple hadn't been tried before as rootstock for almonds. This spring, several dozen cuttings of Nonpareil budwood will be grafted onto Deep Purple rootstock for test plantings in California. That state produces 99 percent of America's almond harvest, worth more than $1 billion to growers in 1996.
Horticultural Crops Research Laboratory, Fresno, CA
Craig A. Ledbetter, (209) 453-3064, jlitster@qnis.net

A new, inexpensive plastic trap could help farmers protect cotton and other crops from silverleaf whiteflies. First discovered in this country in 1986, the pests have cost U.S. agriculture more than $1 billion dollars from 1990 to today. Scientists are evaluating the new traps to determine if a specified number of captured adult whiteflies could help growers decide the need to apply insecticide or other control methods. The trap consists of a 12-ounce clear plastic cup inverted over a bright yellow base. ARS scientists who developed it have applied for patent protection. They initially tested the trap for monitoring whiteflies in western cotton fields. The scientists say the trap might also be used--along with parasitic wasps--in greenhouses to control whiteflies with little or no need for chemical insecticide. (PATENT APPLICATION 08/779,066)
Western Cotton Research Laboratory, Phoenix, AZ
Chang-Chi Chu/Thomas J. Henneberry, (602) 379-3524, thenneb@asrr.arsusda.gov

Last Updated: April 25, 1997
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