Synergistic effect and field efficacy of penoxsulam mixed with diflufenican against weeds in transplanted rice

Diflufenican is a carotenoid biosynthesis inhibiting herbicide, the synergistic effect, and field efficacy of diflufenican mixed with acetolactate synthase inhibiting herbicide penoxsulam against weeds in rice were evaluated in greenhouse and field. The results showed that penoxsulam combined with diflufenican exhibited an additive effect for the control of Echinochloa crusgalli, Digitaria sanguinalis, Cyperus difformis and Eclipta prostrata. When the dose ratio of penoxsulam and diflufenican was (1-2)﹕(5-10), the weed control efficacy was higher than penoxsulam or diflufenican applied alone. The results of field experiments showed that the penoxsulam + diflufenican 300 g/L SC was safe for transplanted rice, and had good efficacy against E. crusgalli, C. difformis, Ammannia arenarid, and Ludwigia prostrata by spraying treatment on stem and leaf of rice 8 days after transplanting, especially to the notorious weeds such as A. arenarid and L. prostrata. The ratios of weed density and the fresh weight reduction were 93.8%-95.8% and 94.1%-96.1% 35 days after treatment with the doses of the active ingredients as 112.5-135.0 g/hm². The mixtures had significantly higher control efficacy than the conventional herbicides bensulfuron methyl + acetochlor 22% WP and penoxsulam or diflufenican alone. The combination of penoxsulam and diflufenican was safe for rice and could expand the weed control spectrum with high efficacy, which could be used in transplanted rice fields for annual weed control.