WEED CONTROL DURING CICER MILKVETCH ESTABLISHMENT AND YIELDS IN SUBSEQUENT YEARS

Abstract

Cicer milkvetch was established in 1978, 1979, and 1981 on irrigated land at the Lethbridge Research Station. Weed control treatments were applied only during the establishment year (year 1). Treatments included none (check), barley companion crop, trifluralin, EPTC, diclofop, 2,4-DB, combinations of bromoxynil with trifluralin and EPTC, and combinations of 2,4-DB with diclofop and sethoxydim. In year 1, herbicide treatments increased cicer milkvetch yields but cicer milkvetch yields remained less than 100 g m−2 even when there was a substantial reduction in total weed yield due to herbicide treatments. In year 2, cicer milkvetch yields were greater in all herbicide treatments than in the check. For experiments established in 1978 and 1981 forage yields in year 2 averaged about 50% in weed content when cicer milkvetch was established without weed control, compared with 6% when herbicides were applied. Thus, herbicide treatments were required in year 1 for the production of acceptable forage in year 2. In all experiments, by year 4 cicer milkvetch contributed more than 67% of the total yield and the remainder was mainly dandelions and perennial grasses. Weed control treatments in year 1 had little effect on cicer milkvetch, dandelion, or perennial grass yields by year 4.Key words: Astragalus cicer, trifluralin, EPTC, dandelion