PERSISTENCE OF INSECTICIDAL CHEMICALS IN SOILS TREATED WITH GRANULAR FORMULATIONS OF ALDICARB AND THEIR UPTAKE BY POTATO PLANTS

Potatoes were grown in Plainfield sand and muck treated, in furrow, wi th aldicarb (Temik 15G, 3.36 kg AI/ha). Soils were contained in 2 m(2) field plots and had not been treated previously with pesticides. Soil , seed pieces, foliage and tubers were analyzed for the insecticide an d its sulfoxide and sulfone metabolites during the 12 wk following pla nting. The disappearance of aldicarb from the soil was accompanied by partial conversion to the sulfoxide and sulfone. After increasing rapi dly during the first 2 wk, the aldicarb concentration in the seed piec e declined and a similar concentration of aldicarb sulfoxide accumulat ed which subsequently slowly disappeared. Aldicarb sulfoxide was the m ajor insecticidal material in the new foliage. High initial concentrat ions, observed at 3-4 wk, declined by about 90% after 6 wk. Aldicarb s ulfoxide residues of 2-4 ppm in the first new tubers at 6 wk declined by 90% by 12 wk. Potatoes were also grown under greenhouse conditions in Plainfield sand treated with Temik 10G at rates equivalent to 1.68, 3.36 and 6.72 kg AI/ha. Maximum aldicarb sulfoxide concentrations in soil, seed piece and foliage increased with application rate. The sulf oxide was much more persistent in the soil and foliage than in the fie ld experiment indicating the importance of environmental factors to it s behaviour in both soil and potato plants.