The growth of two mallow family weeds, velvetleaf and prickly sida, was inhibited 50% when seedlings were treated with less than 200 g ai/ha of thidiazuron. Spurred anoda was unaffected by treatment with up to 1120 g/ha of thidiazuron. Cotton, okra, and hibiscus, all in the mallow family, also were susceptible to thidiazuron treatment. Leaf development in 2-week-old cotton seedlings was inhibited 20% by less than 35 g/ha thidiazuron as were seedling okra and hibiscus. Plants of all these susceptible species were more resistant when grown for 2 months before treatment. Seedlings of soybean displayed localized injury after treatment, but plant height, biomass, and seed production were not significantly affected 10 weeks after treatment with up to 1120 g/ha thidiazuron. Seedlings of corn appeared unaffected by treatment with up to 1120 g/ha thidiazuron.