Precision Placement of Herbicides for Weed Control in Seedling Alfalfa

During the planting of alfalfa (Medicago sativa L.), ethyl N,N-dipropylthiocarbamate (EPTC) was applied in subsurface bands beneath the legume seed and each of three triazine herbicides or EPTC was placed in subsurface bands between the rows. Triazines used were 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine), 2-chloro-4-ethylamino-6-isopropylamino-5-triazine (atrazine), and 2-isopropylamino-4-methoxyethylamino-6-methylmercapto-s-triazine (hereinafter referred to as G-36393). EPTC applied between and within the rows, as well as simazine between the rows and EPTC within the rows, gave superior weed control with little chronic effect on alfalfa. Alfalfa yields following both treatments were increased. Other treatments were unsatisfactory because of poor weed control or because of serious damage to alfalfa.