Published online by Cambridge University Press: 12 June 2017
Weed control with thiameturon applied postemergence at 8 to 32 g ai/ha varied with species, growth stage, addition of surfactant, and environmental conditions. Pennsylvania smartweed control was excellent, velvetleaf control ranged from poor to excellent, and common lambsquarters control was poor with thiameturon applied without surfactant. When surfactant was added to the thiameturon spray mixture, velvetleaf and common lambsquarters control was >85% at 8 g/ha when weeds were growing actively and at 16 g/ha when weeds were under moisture stress. However, in weed-free studies, corn yields were reduced by 35 kg/ha for each 1 g/ha thiameturon applied in 1986 and by 10 kg/ha for each 1 g/ha thiameturon applied in 1987 when surfactant was added to the spray mixture. When no surfactant was added, yields were reduced 12 kg/ha for each 1 g/ha thiameturon applied in 1986 but were not reduced in 1987.