Chemical control options for the dicamba resistant biotype of fathen (<i>Chenopodium album</i>)

Abstract

Three field trials were conducted over two growing seasons to evaluate the efficacy of potential selective postemergence herbicides against dicamba resistant fathen (Chenopodium album) Results confirmed the presence of the biotype which tolerated dicamba up to 2400 g/ha eight times the recommended field rate Postemergence applications of bromoxynil pyridate nicosulfuron and mesotrione all showed equally good efficacy on both susceptible and resistant biotypes Flumetsulam provided good control in one of the three trials Nicosulfuron and mesotrione provided long term residual control in all trials with nicosulfuron also being more effective on grass weeds The 2400 g/ha rate of dicamba severely damaged the maize crop resulting in increased weed cover and reduced grain yield Numbers of viable fathen seeds in the soil at the end of the growing season remained similar to those recorded before planting except in plots that provided good control of fathen where numbers had dropped considerably