Interaction of Alachlor and Carbofuran

The combination of the herbicide 2-chloro-2′,6′ diethyl-N-(methoxymethyl) acetanilide (alachlor) with the insecticide 2,2-dimethyl-2,3-dihydrobenzofuranyl-7- N -methyl-carbamate (carbofuran) interacted synergistically to reduce barley [ Hordeum vulgare L. ‘Larker’] but not corn [ Zea mays L. ‘Michigan 400’] growth. Alachlor alone increased the respiration rate of barley. Accumulation of 14 C from 14 C-alachlor was greater in the plant roots than shoots. The increased accumulation of alachlor in the roots was accentuated by a reduced rate of alachlor metabolism. The basis for the observed interaction appeared to be greater alachlor uptake by barley plants grown from seed treated with carbofuran. A statistical procedure for pesticide combinations in experiments with a completely randomized design was developed for the calculation of interaction significance.