New Bioherbicide Controls Several WeedsBy
A fungal compound--normally undesirable because it can promote food
spoilage--killed jimsonweed and other pesky broadleaf weeds in lab
studies at USDA's Agricultural
Weeds in corn, soybeans and other row crops cost farmers billions of
dollars in losses and reduced crop yields. But the fungus-produced
compound, known as AAL-toxin, could reduce farmers' reliance on
synthetic weed-killing chemicals if it passes additional tests and is
developed as a commercial product.
ARS has patented AAL-toxin as a bioherbicide--a nature-based weed
killer. The agency and DuPont
Agricultural Products, Newark, Del., have a cooperative research
and development agreement to test and further develop AAL-toxin for
AAL-toxin is produced by the fungus Alternaria alternata f.
sp. lycopersici. ARS scientists found that the AAL-toxin kills a
number of weeds that are pests of row crops such as soybeans, cotton,
rice and corn. Weeds that succumbed in lab tests include duckweed (Lemna
species), jimsonweed (Datura stramonium), black nightshade (Solanum
nigrum), prickly sida (Sida spinosa), redroot pigweed (Amaranthus
retroflexus) and northern jointvetch (Aeschynomene virginica).
Some A. alternata fungi are known to promote spoilage of
fruits, vegetables and grains. But use of AAL-toxin to kill weeds
doesn't pose a hazard to the crops and should be safe for the
environment and wildlife.
AAL-toxin affects broadleaf weeds, but not grasses. It can be used
before or after weeds emerge and is effective as a spray, mixed with
water or alone, according to Hamed K. Abbas. He and colleagues
conducted lab studies at ARS'
Weed Science Research Unit in Stoneville, Miss.
Scientific contact: Hamed K. Abbas and C. Douglas Boyette,
Weed Science Research Unit, Stoneville, Miss., phone (601)
686-5313 [Abbas], (601) 686-5217 [Boyette], fax (601) 686-5422,