Extract Curtails Snails
A natural ingredient in the oil of a variant of the weed known as mugwort
could lessen the woes of U.S. catfish farmers and Asian rice growers.
Vulgarone B has proved just as effectiveand faster actingthan
the current treatment against golden apple snails. These hungry pests
make quick work of rice fields, feeding on the base of paddy seedlings
and on plant stems and leaves. They have caused great losses to rice
farmers in Southeast Asia in the past two decades.
Vulgarone B has also controlled ram's horn snails. They serve as intermediate
hosts for a parasitic flatworm, Bolbophorus confusus, that has
plagued U.S. catfish farmers, killing smaller fish and stunting those
that survive. Vulgarone B can be sprayed, placed in attractant traps,
or applied directly to pond or paddy water. The compound has also shown
activity against fungi that cause anthracnose disease in strawberries.
Testing on mammals has yet to be done.
Kumudini M. Meepagala,
Products Utilization Research Laboratory, Oxford, Mississippi; phone
Tractors and No-Till
Soil compaction is not a good thing. It can interfere with roots' normal
growth, restrict infiltration of water, and increase runoff and soil
erosion. Driving heavy machinery through conventional-till and no-till
fields causes soil compaction under the tires. To see whether there's
a difference between soil compaction on tilled and no-till soils, researchers
attached sensors to tractor tire tread and compared the effects of tire
pressure (that is, the pressure or force exerted on the field by the
tire) on both types of fields. They found tire pressure to be more uniform
on tilled soils than on untilled clay soils. As for tractive efficiency
(the measure of efficiency with which a tire converts power applied
to the wheel to actual work done) it proved to be the same on tilled
and no-till soils. Since a tractor's fuel efficiency increases with
its tractive efficiency, fuel consumption for a particular use of a
tractor on tilled and no-till soils would be about the same.
Thomas R. Way, USDA-ARS
National Soil Dynamics
Laboratory, Auburn, Alabama; phone (334) 844-4753.
Water Turkeys Foiled by Twine
Researchers have tested a low-tech solution to the problem of poaching
by double-crested cormorants, often called water turkeys. These migratory
diving birds winter in the Delta region, where they voraciously feed
on channel catfish fingerlings and any other fish they can swallow.
Each one eats up to a pound and a half a day.
Seeking an inexpensive, easily set up, environmentally benign way to
discourage this predation, researchers installed twine barriers across
test ponds. It took about 3 hours for a three-person team to string
a 15-acre pond, placing posts at 100-foot intervals, stretching the
twine across the width of the pond, and maintaining the string 3 feet
above the water in the middle of it.
Using four ponds at each of six privately owned catfish farms, only
2.3 cormorants per hour, on average, landed on ponds where the twine
was used, compared to 10.6 birds on unstrung ponds. Seeing fewer birds
on twined ponds apparently discouraged others from attempting to land.
Andrew A. Radomski,
USDA-ARS Harry K. Dupree Stuttgart
National Aquaculture Research Center, Stuttgart, Arkansas; phone
"Science Update" was published in the January
2004 issue of Agricultural Research magazine.