Response of Fenoxaprop and Other Herbicides on Isoproturon Resistant and Susceptible Biotypes of Little Seed Canary Grass and Other Weeds in Wheat

Efficacy of fenoxaprop applied alone and tank mix with isoproturon and metsulfuron was tested against isoproturon resistant and susceptible Phalaris minor and other weeds in wheat during winter seasons of 1995–96 and 1996–97. Fenoxaprop alone at 100 and 120 g ha⁻¹ provided excellent control of isoproturon susceptible little seed canary grass and wild oat. Metsulfuron at 4 g ha⁻¹ was highly effective against most of the broadleaf weeds. However, tank mixture of isoproturon and fenoxaprop (10: 1) at 1.0 and 1.25 kg ha⁻¹ and isoproturon alone at 1.0 and 1.25 kg ha⁻¹ proved very effective against mixed weed flora and provided grain yield of wheat statistically similar to weed free yield. Combination of fenoxaprop and metsulfuron at 80+2 g ha⁻¹ proved next best in minimising complex weed flora and giving satisfactory wheat yield. Fenoxaprop alone was found highly effective against isoproturon resistant and susceptible biotypes of little seed canary grass. The GR 50 value of fenoxaprop ranged from 20 to 23 g ha⁻¹. It was found that isoproturon resistant biotypes required 8 to 11 times more isoproturon as compared to susceptible biotypes of little seed canary grass to bring desired control.