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Science Update
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| Pest's Peptides Could Cramp Its
Style
Peptides, compounds that may play important roles in controlling feeding and
reproduction, have been detected in extracts from an important soybean pest.
Soybean growers currently use resistant varieties and crop rotation to battle
their greatest foe, the soybean cyst nematode. This microscopic, wormlike
parasite costs growers about $1.5 billion annually. But resistant varieties are
not effective against all races of the nematode and usually yield less than
susceptible varieties do when nematodes are absent.
The discovery of these peptides in parasite extracts opens a new path for
scientists who are investigating naturally based controls for soybean cyst
nematodes. The key may be the peptides' potential involvement in regulating
nerve transmission and muscle activity in these pests, as well as their feeding
and movement. At least three different peptides have been observed in the
nematodes grown on soybean plants. The peptides in soybean cyst nematodes
differ from those in nonparasitic species, and their levels vary during the
worms' development. Researchers are focusing on those which would be most
active in female nematodes, since they will lay the eggs that yield new
generations of hungry, root-eating offspring.
Edward P. Masler, USDA-ARS
Nematology
Laboratory, Beltsville, Maryland; (301) 504-8732. |
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Vetch-a-Matic Beetle Control
A recent study showed that an organic mulch made from a cover crop of hairy
vetch can reduce Colorado potato beetle damage. This notorious pest ravages
potato, eggplant, and tomato crops, causing annual crop losses and
insecticide-related expenses. Many growers are using imadacloprid, a new
systemic insecticide that provides excellent control. But the pest also has a
proclivity for developing resistance to insecticides, so there is concern that
appropriate measures be taken to prevent that. A nonchemical control such as
hairy vetch mulch could be a useful part of a sustainable integrated pest
management strategy for Colorado potato beetles.
In the study, hairy vetch was planted in the fall; then the vetch was mowed and
killed in the spring before tomatoes were transplanted into it. The vetch
impeded the beetles' movement and, since it is a legume, added nitrogen to the
soil. Fewer beetles infested tomatoes transplanted into the mulch, compared to
tomatoes transplanted into black plastic mulch. And yields of staked,
fresh-market tomatoes grown in the mulch were comparable to yields from
insecticide-treated fields.
Kevin Thorpe, USDA-ARS
Insect Biocontrol
Laboratory, Beltsville, Maryland; phone (301) 504-5139. |
| For Better Surface Water Quality,
Dig Ditches
Drainage ditches are a common feature in the agricultural landscape. They carry
runoff water from fields after heavy rains. Now a first-of-its-kind study that
looked at the transport and fate of two pesticides in vegetated agricultural
drainage ditches suggests they're valuable tools for reducing the amount of
chemicals that enter bodies of water. Researchers simulated storm runoff events
in order to evaluate the role of edge-of-field best management practices in
preventing potential contaminants from leaving agricultural lands.
The researchers attempted to pinpoint the test ditch's efficacy in keeping
irrigation water and pesticides from getting into water bodies. They found that
it trapped 60 to 90 percent of the herbicide atrazine and a commonly used
insecticide Karate carried in runoff water. Its vegetation enabled it to work
like wetlands to sequester storm runoff materials. Thus, ditches appear to be a
simple, low-tech, inexpensive way to improve surface water quality. Farmers and
conservationists who want to reduce the chemicals, nutrients, and sediment
leaving their fields may find maintaining ditches a practical and effective
alternative management practice.
Matt Moore, USDA-ARS
National
Sedimentation Laboratory, Oxford, Mississippi; phone (601) 232-2955.
Better Retting for a Fledgling Flax Industry
A new retting process could revolutionize linen fabric production in the United
States. Enzymatic retting uses a chemical to break down calcium bonds in the
flax plant, allowing easier loosening of flax fiber so it can be extracted from
the plant and processed into linen. Researchers have an agreement with the
Center for American Flax Fiber to evaluate the process. They will also
establish standards for fiber strength, length, fineness, nonfiber content, and
color.
North America is the largest producer of flaxseed and related products that
yield millions of tons of fiber. But only a fraction of it is used for
industrial purposes. The nation now imports about $150 million of flax fiber,
flax fabric, and flax-containing yarn annually—which are converted into
about $500 million in finished products. Scientists hope enzymatic retting will
help establish a domestic flax fiber industry.
Danny E. Akin, USDA-ARS
Richard
B. Russell Research Center, Athens, Georgia; phone (706) 546-3482.
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"Science Update" was published in the
September
2000 issue of Agricultural Research magazine.
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