The objectives of this study were to evaluate the leaching of isoxaflutole and the safeners R-29148 and furilazole to test the hypothesis that safeners and isoxaflutole were moving at different rates through the soil profile. The isoxaflutole movement down soil columns was measured by evaluating the visible injury on crop and weed bioassay species seeded into columns split longitudinally. The movement of the safeners was measured by evaluating the isoxaflutole injury to the crop assay species compared to the injury observed without a safener present. The results indicated that a heavy rainfall event could move isoxaflutole through the soil profile in a pulse pattern. If the herbicide pulse moved into the rooting zone of corn, injury resulted. The herbicide safeners leached more slowly than isoxaflutole. For the safeners to be effective, their movement needed to be similar to that of isoxaflutole. Applying a polymeric carrier with the WDG formulation of isoxaflutole reduced leaching compared to two commercial isoxaflutole formulations.

Corn inbreds are often more sensitive to herbicides than hybrids. Field experiments were conducted with three corn inbreds to (1) evaluate inbred sensitivity to the acetamide herbicides acetochlor, dimethenamid, flufenacet, and metolachlor, (2) compare the effects of various crop safeners in combination with acetochlor and metolachlor, and (3) measure the effect of herbicide microencapsulation on acetochlor injury. Herbicides were applied preemergence at the registered rate and at two, three, or four times the registered rate in corn. Injury ratings, plant population, and the percentage of plants showing acetamide injury symptoms were used to measure herbicide effect. The inbreds ‘Mo17’ and ‘Great Lakes 15’ (GL15) were sensitive to acetamide injury. Reductions in plant population and increases in the injury rating and the percentage of injured plants were caused by acetochlor, dimethenamid, flufenacet, metolachlor, and flufenacet + metribuzin when applied at three times the registered rate. The inbred ‘B73’ was not injured. The safeners benoxacor and dichlormid reduced injury caused by metolachlor. The percentage of plants injured by metolachlor 15 days after treatment (DAT) was lower when benoxacor was the safener compared to dichlormid. By 28 DAT, plants treated with safeners recovered from injury, and there were no differences between the treatments. The safeners dichlormid and furilazole reduced, but did not always eliminate, injury caused by acetochlor applied at three times the registered rate. Microencapsulation of acetochlor reduced injury to GL15. When the safeners dichlormid or furilazole were included in an acetochlor formulation, microencapsulation did not further reduce corn injury.