Biological activity of pyribenzoxim in winter wheat and associated weeds

Pot and field tests were conducted to evaluate the efficacy of pyribenzoxim for winter weeds in wheat. In the pot tests, pyribenzoxim, at 50 g ha −1 , controlled certain biotypes of blackgrass, including a fenoxaprop‐P‐ethyl‐resistant biotype (the “Notts” biotype). A chlorotoluron‐resistant blackgrass (the “Peldon” biotype) was not controlled. Cleaver, at the three‐to‐four‐leaf stage, was completely controlled by pyribenzoxim at 30 g ha −1 . In the field, the application in December gave good control of common chickweed, but did not control other weeds. No damage to wheat was observed with this rate of pyribenzoxim in December. The application in March gave complete control of blackgrass , hairy chess, and soft brome at 70 g ha −1 , and cleaver at 140 g ha −1 . The partial control of corn poppy and field violet was achieved. The March application scorched the wheat at 50–70 g ha −1 , with prolonged stunting at 100–140 g ha −1 . In conclusion, it was shown that pyribenzoxim had potential as a wheat herbicide, but needed further fine‐tuning to find an optimum dosage.