
Sweeping Weeds Off the Wheat
FieldBy Kathryn Barry
Stelljes January 17, 1997A specially designed cultivator can help Pacific Northwest wheat growers
sweep away about two-thirds of their potential downy-brome
problem--up to a year before the costly weed could otherwise take over their
wheat fields. Downy brome and other bromes infest 14 million acres of western winter wheat
and cost growers $300 million a year in lost yields. The broad, flat sweep cultivator makes weed seeds germinate quickly,
scientists with USDAs
Agricultural Research Service say. Weeds
then can be killed by herbicide or cultivation in the fallow year. If growers dont act, the scientists warn, the seeds stay dormant
through winter and germinate the next fall, when wheat is again planted. On January 8, the scientists reported findings from their field tests with
the tactic at the Solutions to Environmental and Economic Problems (STEEP III) Conservation Farming Conference
in Kennewick, Wash. In the field tests, the ARS scientists measured survival of downy brome seed
using five cultivation techniques: no-till, sweep, light harrow, shallow disc
and skew-treader. In years with a dry fall, 13 percent of downy brome seeds survived with the
sweep cultivator, compared with 40 percent with no-till. In years with a wet
fall, only 3 percent of the seed survived with the sweep versus 9 percent with
no-till. Harrowing was largely ineffective. Shallow discing cut seed survival
dramatically, but buried much of the soil-protecting residue. The sweep cultivator also helps reduce soil erosion because the sweep does
not invert soil or chop straw left to shield the soil. Scientific contact: Alex Ogg, USDA-ARS Nonirrigated Agriculture Weed
Science Research Unit, Pullman, Wash., phone (509) 335-1551 U.S. Department of Agriculture | |