Pretilachlor and bensulfuron methyl interactions in paddy weed control

The efficacy of pretilachlor from chloroacetamide herbicides inhibiting lipid synthesis and bensulfuron from sulfonylureas urea inhibiting the synthesis of enzyme acetolactate synthase in the control of barnyardgrass and bulrush were investigated in sole and mixed applications at 0, 25, 50, 75, 100 and 125% of the recommended doses. The results showed that weed control in response to different doses of two herbicides could be expressed by logistic dose-response model (R2≥95%). The required dose for 50% reduction of barnyard grass biomass (ED50) in the treatment with pretilachlor and bensulfuron was 17.1% and 24.7% of the recommended dose, respectively, and 32.3% and 26.4% of the recommended dose for bulrush respectively, indicating higher efficiency of pretilachlor in barnyardgrass and bensulfuron in bulrush controls. While pretilachler provided complete control of barnyardgrass, none of the herbicides were able to completely control bulrush up to 125% of the recommended dose. According to the fitted dose response logistic model (R2≥95%), mixing the recommended doses of bensulfuron with 75% of recommended dose of pretilachlor or the recommended dose of pretilachlor with 25% of recommended dose of bensulfuron resulted in 100% control of bulrush. Today, sedges are the most abundant and diverse weeds in rice fields, and according to the results of this study, to control the most prevalent weed of this group, bulrush, mixing of herbicides is necessary. By mixing the pretilachlor and bensulfuron herbicides, it is possible to control bulrush and barnyardgrass, the two key weeds of paddy, with lower doses of these herbicides, which require further studies in field conditions to determine the appropriate dose.