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

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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.