Agronomy Library > Annual Weeds

Crop Rotation Effects on Downy Brome in Winter Wheat
Author: R. E. Blackshaw
Date Created: February 10, 1994
Last Reviewed: January 21, 2009
Document Source: Weed Technology, Volume 8: 728-732 Summary Downy brome control in winter wheat is often inadequate. The effects of two crop rotations and three tillage intensities on downy brome populations and crop yields were determined in an experiment at Lethbridge from 1987-1993: - Downy brome densities in continuous winter wheat increased from 24 to 970 plants/m2 between 1988-1993; and were often higher with zero tillage. - Inclusion of fallow or spring canola in rotation in winter wheat suppressed downy brome densities to less than 55 and 100 plants/m2, respectively over the six years - In continuous winter wheat, yield decreased as downy brome densities increased progressively over years, indicating that monoculture winter wheat production will not be viable in regions where downy brome is prevalent unless effective herbicides are developed. In more arid areas of Canadian prairies, a winter wheat - fallow rotation may be most suitable but in higher precipitation areas, a winter wheat - canola rotation is a viable alternative. Crop rotation is a key component in an improved management system for control of downy brome.