Published online by Cambridge University Press: 12 June 2017
Weed control and corn vigor were evaluated to determine the effects of application rate, timing, and other POST herbicides on primisulfuron activity. Corn injury caused by primisulfuron was very low. Weed control varied with species and stage of growth. Primisulfuron showed high activity on emerged johnsongrass, particularly with early postemergence (EP) and mid postemergence (MP) applications. However, these treatments did not provide full season control of this species due to regrowth from rhizomes and continuous germination of new seeds. Primisulfuron controlled giant foxtail with the EP timing (< 5 cm weed height), but not with MP and late postemergence (LP) applications. Common lambsquarters and redroot pigweed control was most effective with EP applications. Primisulfuron in combination with cyanazine, atrazine, cyanazine plus tridiphane, atrazine plus tridiphane, bentazon, 2,4-D, dicamba, or paraquat controlled common lambsquarters and redroot pigweed better than primisulfuron applied alone. Johnsongrass control decreased when primisulfuron was combined with paraquat or 2,4-D and giant foxtail control decreased when primisulfuron was combined with 2,4-D or dicamba.