Influence of Available Soil Water Content, Temperature, and CGA-154281 on Metolachlor Injury to Corn

Abstract

The effects of the antidote CGA-154281, available soil water (ASW), and soil temperature on corn injury from preemergence applications of metolachlor were evaluated in field and growth chamber studies. In field studies, metolachlor at rates of 5.6, 8.4, and 11.2 kg ha–1caused corn injury when there was sufficient ASW before corn emergence to activate the herbicide. Injury was prevented when CGA-154281 was applied with metolachlor (30:1, metolachlor:CGA-154281 by wt). The effects of surface-soil ASW, soil temperature, and CGA-154281 on corn tolerance to metolachlor were further evaluated in growth chamber studies. Corn injury from metolachlor was more severe when the surface soil was wet for 5 days immediately after herbicide treatment than when the surface-soil was dry. Corn injury from metolachlor also was greater when corn was grown under cool temperatures (21/13 C, day/night) than when grown under warm temperatures (30/21 C, day/night). CGA-154281 conferred protection against metolachlor injury regardless of surface soil ASW or growth temperature.