CROPPING SYSTEMS CONTROL WINTER ANNUAL GRASS WEEDS IN WINTER-WHEAT

Downy brome (Bromus tectorum L.), Jointed goatgrass (Aegilops cylindri ca Host), and volunteer cereal rye (Secale cereale L.) are winter annu al grass weeds that are increasingly troublesome in the winter wheat ( Triticum aestivum L. emend. Thell.)-fallow rotation areas of the weste rn USA. Six dryland cropping systems-continuous no-till winter wheat, winter wheat-fallow with fall tillage, winter wheat-fallow with fail a pplied herbicide, winter wheat-fallow-fallow, winter wheat-sunflower-f allow, and winter wheat-prose millet-fallow-were compared for their ef fect on winter annual grass densities in winter wheat. Winter annual g rass densities averaged 145, 4.4, and 0.4 plants/sq yard for the 1-, 2 -, and 3-yr systems, respectively. Eradication of the winter annual gr asses was not achieved with any of the systems. Dockage and foreign ma terial levels in wheat grain were lower in 3-yr than in 2-yr cropping systems. Jointed goatgrass was the most persistent annual grass invest igated.