Control of Yellow Rocket and White Cockle in Established Alfalfa

Yellow rocket (Barbarea vulgarisR. Br.) was effectively controlled in established alfalfa (Medicago sativaL.) by September 15 applications of 2-chloro-4,6-bis(ethylamino)-s-triazine (simazine), 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine), 3-tert-butyl-5-chloro-6-methyluracil (terbacil), and 2-sec-butylamino-4-ethylamino-6-methoxy-s-triazine (hereinafter referred to as GS 14254). White cockle (Lychnis albaMill.) was more difficult to control, but simazine was the most effective herbicide. Herbicide applications in early October reduced reserve nonstructural carbohydrate accumulations in roots of yellow rocket by November 15 but not in white cockle. Alfalfa yields were not reduced by two consecutive autumn applications of the herbicides at rates that provided adequate control of yellow rocket and white cockle.