Annual surveys of pesticide applications and terminal residues on 32 to 34 Ontario farms producing flue-cured tobacco, Nicotiana tabacum L., were continued between 1980 and 1985. Applications of synthetic pyrethroids increased for cutworm control and chlorpyrifos applications decreased. Acephate was most widely used for foliar insects followed by Bacillus thuringiensis Berliner and oxydemeton-methyl. Metalaxyl was widely applied following the outbreak of blue mold (Peronospora tabacina Adam) in 1979 but became insignificant by 1983. Synthetic pyrethroid residues were absent from cured leaf where the label recommendations were followed, but residues were found where topical applications were made in mid-season. Metalaxyl and diphenamid residues appeared in cured leaf where they were used for disease and weed control, respectively. Diphenamid residues were present predominantly as the N-methyl metabolite. Minor residues of several organochlorine insecticides were found in both soil and cured leaf 5 to 15 years after their use was terminated. Organophosphorus insecticide residues were absent or at trace levels in soils and curd leaf. Acephate residues were rarely found but methamidophos residues were present. These residues were found in cured leaf at all stalk positions but mainly in sand leaves.

(Full article published with kind permission from "Tobacco International")