Fall and Spring Herbicide Treatment for Minimum-Tillage Seeding of Alfalfa (Medicago sativa)

Abstract

Experiments were conducted at three locations to evaluate the efficacy of fall and spring herbicide treatments for vegetation control and enhancement of alfalfa (Medicago sativaL.) establishment. on a sward dominated by quackgrass [Agropyron repens(L.) Beauv.], fall and spring glyphosate [N-(phosphonomethyl) glycine] treatments were equally effective in reducing competition from quackgrass and in establishing alfalfa. on a mixed grass sward, spring and fall glyphosate treatment resulted in similar alfalfa yields with early spring seeding; however, alfalfa yields were lower with delayed seeding on fall-treated plots, compared with spring treatment, because of greater weed competition. Pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl) benzamide] applied in the fall controlled perennial grasses, and when it was followed by paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) in the spring controlled broadleaf weeds as well, resulting in greater alfalfa yields compared with pronamide alone. Alfalfa established more slowly in the paraquat-treated and check plots, than in glyphosate-treated plots.