Butylate and Carbofuran Interaction in Barley and Corn

Radicle length of barley ( Hordeum vulgare L. ‘Larker’) seedlings was greatly reduced by the combination of the herbicide S -ethyl diisobutylthiocarbamate (butylate) applied in combination with the insecticide 2,2-dimethyl-2,3-dihydrobenzofuranyl-7- N -methylcarbamate (carbofuran). Corn ( Zea mays L. ‘Michigan 400’) seedlings were not similarly affected. Carbofuran interacted with butylate to reduce synergistically the root and shoot growth of barley but not that of corn. The combination of these two carbamate pesticides synergistically increased respiration in barley. The basis for these interaction effects in barley appeared to be decreased metabolism of butylate and increased respiration in the presence of carbofuran. Although the same metabolism trend was apparent in tolerant corn, the butylate level was much lower since the absorption of butylate was reduced by the carbofuran seed treatment. The 14 C from 14 C-butylate preferentially accumulated in barley shoots and corn roots.