Abstract
Translocation and metabolism of a systemic fungicide procymidone [Sumilex®, N-(3, 5-dichlorophenyl)-1, 2-dimethylcyclopropane-1, 2-dicarboximide] radiolabeled at the carbonyl carbon were examined in cucumber and bean plants under laboratory conditions. The fungicide disappeared from the plants with a half-life of 20 days, after foliar application at a rate of 250μg per leaf. Procymidone was metabolized in plants via hydroxylation at the methyl group or the 4-position of phenyl group, or hydrolysis at the cyclic imide linkage. Very little of radioactivity translocated to other parts of the plants including edible portions. When the fungicide was applied to the surface of a cucumber fruit, approximately 24% of the applied radioactivity penetrated into the fruit in a day. However, there was no significant increase of radioactivity in the fruit thereafter. When bean plant seedlings were cultivated for 42 days in Kodaira light clay and Takarazuka loamy sand soils treated with 10ppm of 14C-procymidone, shoots, and pods and seeds contained 12.3-15.3ppm and 0.42-0.66ppm of 14C, respectively. Preincubation of procymidone treated soils for up to 5 months significantly lowered 14C residues taken up in plants, especially in shoots and pods and seeds.