Evaluation of Insecticide Seed Treatments to Protect Rice (Oryza sativa) Against Various Herbicides

The increase in herbicide-resistant weeds in Arkansas crop fields has led to the need for new herbicide modes of action for use in all crops. This need has led to the introduction of technologies that can be devastating to conventional rice crops. Field observation, noted that insecticide seed treatments used in rice could potentially reduce the effects of off-target movement of herbicides onto rice crops and possibly reduce the negative effects of some herbicides applied directly to rice. Research was conducted to determine if insecticide seed treatments could reduce the harmful effects of drift from imazethapyr and glyphosate onto conventional rice, and if so, which insecticide seed treatments provided adequate protection. In addition, research was conducted to determine if thiamethoxam, a popular insecticide seed treatment, could reduce the negative effects of some acetolactate synthase (ALS)-inhibiting, preemergence and postemergence herbicides for better or future use in rice. The use of insecticide seed treatments containing thiamethoxam and clothianidin resulted in less rice injury, more groundcover, and increased grain yields following simulated herbicide drift events compared to a fungicide-only seed treatment. Thiamethoxam seed treatment also reduced the amount of injury caused by ALS-inhibiting herbicides applied to imidazolinone-resistant varieties of rice. In addition, thiamethoxam reduced injury from the preemergence and postemergence herbicides; however, individual interactions were observed in terms of yield for the herbicides. Overall, this research confirms the hypothesis that insecticide seed treatments can provide some safening from low rates of harmful herbicides and reduce some of the negative effects of injurious herbicides commonly used in rice production