EFFECT OF HERBICIDES FOR THE CONTROL OF WEEDY GRASSES ON SEED PRODUCTION OF BROMEGRASS, CRESTED WHEATGRASS AND TIMOTHY

Herbicides for the control of annual grass weeds were applied to established seed-producing stands of bromegrass (Bromus inermis Leyss.) and crested wheatgrass (Agropyron cristatum (L.) Gaertn.) in spring each year 1979 through 1981 and to timothy (Phleum pratense L.) in 1980 and 1981. Flamprop methyl reduced seed yields in 2 years in bromegrass and in 1 year in crested wheatgrass and timothy. Diclofop methyl and difenzoquat reduced timothy and bromegrass yields, but not yields of crested wheat-grass. Diclofop methyl and flamprop methyl stunted timothy, reduced the number of seed heads formed, and delayed their maturation. Propanil reduced timothy seed yield 1 year, but did not reduce bromegrass yields. Dichlobenil had no deleterious effects.Key words: Bromus inermis, Agropyron cristatum, Phleum pratense, seed production, herbicides