New Strategies on the Way to Help Combat Weeds

Farmers will have to wield a new combination of chemical and tillage weapons to win the war against weeds, now a $15 billion-per-year problem in American agriculture, Agricultural Research Service scientists report.

ARS scientists Robert Masters, Loyd Wax and Doug Buhler are developing new weapons that are lethal to weeds but friendly to the environment. Masters is a range scientist at Lincoln, Neb.; Wax is a research agronomist at Urbana, Ill.; and Buhler is a research agronomist at Ames, Iowa. Each of the scientists evaluated control strategies for common weed problems in their geographic area.

Masters combined herbicides, controlled burning and re-planting of native warm season grasses without tillage to supplant leafy spurge, a noxious weed that threatens Northern Plains grasslands. The result: a 60-percent reduction in spurge populations, a boost in warm season grasses and a more stable soil profile.

Wax showed that farmers need a combination of tillage and herbicides to thwart waterhemp, also called "pigweed" in the Midwest. Pigweed has been increasingly resistant to a group of herbicides known as ALS-inhibiting herbicides. But Wax reduced waterhemp populations when he applied non-ALS-inhibiting herbicides in combination with tillage to disturb the weed's root system.

Buhler studied changes in field cultivation techniques and concluded that some weeds such as hemp dogbane thrive in fields that get little or no cultivation. He recommends developing cultivation strategies that best control weeds by creating the environment least favored by the problem weed. For example, hemp dogbane populations remained steady over a 14-year period when the soil was tilled, but exploded when land operators switched to no-till cultivation.

A detailed story about this research is found in the April 1998 issue of Agricultural Research magazine, the monthly publication of the Agricultural Research Service. To view the current issue visit our website at:

http://www.ars.usda.gov/is/AR/archive/apr98/weed0498.htm

Scientific contacts: Robert A. Masters, Lincoln, Neb., phone (402) 472-1546; Loyd Wax, Urbana, Ill., (217) 333-9653, l-wax@uiuc.edu; Doug Buhler, Ames, Iowa, phone (515) 294-5502, buhler@nstl.gov.