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A Summary Of Reduced-Rate Herbicide Research Underway At CALS

Jerry Doll, extension weed scientist, is comparing reduced herbicide rates with full rates over five years at Lancaster Agricultural Research Station. The research integrates mechanical control and measures yield and the weed seed bank. Mechanical-only weeding systems are included in the trials to compare their effectiveness to the use of herbicides. A primary focus of the research is to analyze what happens to the seed bank in the full range of weed control strategies. Weeds being studied include lambsquarters, pigweed, velvetleaf and foxtails. This is the final year of the study.

David Stoltenberg, weed research scientist, completed a four-year study at Arlington Agricultural Research Station to determine the influence of full-rate pre-emergence broadcast herbicide, half-rate pre-emergence broadcast herbicide plus cultivation and full-rate band herbicide plus cultivation treatments on weed population and seedbank changes in no-tillage, chisel plow, and moldboard plow systems. Results showed that standard and reduced herbicide treatments had similar efficacy over time in each tillage system, and that the weed seedbank decreased up to 50 percent for lambsquarters, 95 percent for giant foxtail, and 92 percent for pigweed by the end of the four years. Stoltenberg and Chris Boerboom, extension weed scientist, intend to conduct on-farm trials in central and southern Wisconsin in 1998.

The UW Nutrient and Pest Management Program has conducted 35 on-farm demonstrations on reduced herbicide rates. Results showed that reduced rates saved Wisconsin farmers an average of $8 an acre compared with labeled rates. Richard Proost, southeast NPM regional agronomist, is currently coordinating an on-farm demonstration in Ozaukee county, and Paul Kivlin, northwest NPM regional agronomist, is currently coordinating an on-farm demonstration in Trempealeau county. This is the second year of reduced rates in the same field in Ozaukee County, and the seventh year of reduced rates in the same field in Trempealeau County. Farmers interested in participating in reduced-rate herbicide demonstrations can contact Proost at (608) 262-7845 or Kivlin at (715) 425-3112.