EFFECT OF CYTOCHROME P450 INHIBITORS ON ACCASE RESISTANT Phalaris minor BIOTYPES.

Phalaris minor Retz. is a major issue in wheat growing areas of Pakistan because it has evolved resistance to ACCase inhibitors herbicides like fenoxaprop due to enhanced metabolic activity to detoxify herbicides. Cytochrome P450 inhibitors such as 1- aminobenzotriazole (ABT) and malathion are expected to increase the toxicity of herbicides against ACCase resistant weeds. In this regard, a wire house experiment was carried to explore the effect of cytochrome P450 inhibitors on ACCase resistant P. minor biotypes. Seeds of nine ACCase resistant P. minor biotypes and susceptibility were sown in pots (5 seeds per pot). After seedling establishment (at 3-4 leaf stage), different doses of cytochrome P450 inhibitors (ABT at 50, 100 and 150 μM and malathion at 500, 1000 and 1500 g a.i. ha-1) were applied 30 minutes before spray of fenoxaprop at 67.5 g a.i. ha-1. Outcomes exhibited that cytochrome P450 inhibitors improved the herbicidal activity of fenoxaprop, significant decrease in fresh and dry weight of resistant biotypes were achieved. Maximum decrease in weight (fresh and dry) was noted for ABT at 50 μM, 100 μM and 150 μM+ fenoxaprop at 67.5 g a.i ha-1. Similarly, percent decrease in dry weight and mortality was also maximum when ABT at 50 μM, 100 μM and150 μM+ fenoxaprop at 67.5 g a.i ha-1 was used. Results conferred the resistance potential of P. Minor biotypes against fenoxaprop and P450inhibitors could be used to synergize the activity of fenoxaprop. [ABSTRACT FROM AUTHOR]