Laboratory Studies on the Behavior of the Herbicide Safener CGA-43089

CGA-43089 [α-(cyanomethoximino)-benzacetonitrile] applied as a seed treatment enables sorghum [Sorghum bicolor(L.) Moench] to tolerate metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide]. Improved tolerance of alexandergrass [Brachiaria plantaginea, (Link) A. Hitchc.]Eleusinespp., proso millet (Panicum miliaceumL.) and rice (Oryza sativaL.) to metolachlor also was demonstrated. Seven sorghum cultivars, representing widely divergent types of germplasm, responded similarly to the safening effect of CGA-43089 when the cultivars were exposed to metolachlor. Treated sorghum seed may be stored more than 1 yr without a loss of safening activity. In these growth chamber experiments, neither extremes of soil moisture nor temperature reduced the effectiveness of the safener. The predominant site of uptake of CGA-43089 is the coleoptile of sorghum seedlings.