English Pea (Pisum sativum) Tolerance to Paraquat and Paraquat Plus Bentazon

Abstract

Field studies were conducted between 1990 and 1992 to determine tolerance of English pea at different growth stages to bentazon (0.56 kg ai/ha) and paraquat (0.14 kg ai/ha), applied alone and in combination. Initial crop injury with paraquat and paraquat plus bentazon averaged 37 and 21%, respectively. Crop injury dissipated by 21 d after treatment. Foliar injury at the different growth stages was equivalent but yields of peas treated at the six-node stage were reduced in two of four trials. Applying paraquat plus bentazon at the earlier growth stages consistently resulted in pea yields equivalent to those of plots receiving trifluralin plus handweeding or bentazon alone. Greenhouse studies were conducted to determine the effect of paraquat plus bentazon on control of selected weeds common to pea production fields. Redroot pigweed, common purslane, and common lambsquarters mortalities were 100, 100, and 90%, respectively, with the bentazon plus paraquat combination. However, barnyardgrass and large crabgrass mortalities decreased 88 and 91%, respectively, when bentazon was added, compared to paraquat alone.