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Selective Biocontrol of Winter Annual Grass Weeds in Winter Wheat

P.A. Harris and P.W. Stahlman
1993 NWCSS Proceedings, Vol. 48
Abstract. Many winter annual grass weeds are difficult to control in winter wheat grown in the Central Great Plains and the western U.S. current chemical weed control methods are either prohibitively expensive or provide inadequate control. Soil bacteria shown to be inhibitory to downy brome, Japanese brome, and/or jointed goatgrass in preliminary laboratory and growth chamber bioassays were evaluated in three years of field studies. In 1990-91, ten bacterial isolates had no significant effect on downy brome under adverse environmental conditions, but a trend toward increased wheat grain yields was observed with two isolates. In a study using single-species plots, several isolates inhibited early growth of both downy and Japanese bromes, but biomass was similar at harvest. It is likely that the competitiveness of wheat, if present in the plots, would have continued to suppress weed growth. Biological weed control agents can become a viable option in integrated past management systems.