Movement and Metabolism of CIPC in Resistant and Susceptible Species

Abstract

Sublethal concentrations of isopropyl N-(3-chlorophenyl)- carbamate (CIPC) labeled with 14C in the ring or side chain were applied to all leaves present or to the roots of redroot pigweed (Amaranthus retroflexus L.), pale smartweed (Polygonum lapathiofolium L.), and parsnip (Pastinaca sativa L.). These species were selected because of their different susceptibilities to CIPC. The herbicide did not move out of the treated leaves in pigweed and smartweed and only slightly in parsnip in 21 days. In root treatment (3 days), the herbicide moved to all plant parts and the extent of movement was essentially the same in all species. Water soluble metabolites, which differed in Rf values were extracted from all three species. The metabolites apparently were not the result of cleavage of the CIPC molecule, but were more likely conjugates of CIPC with natural plant component(s). Very little 14CO2 was released by any of the species in 3 days. These data indicate that differences in movement and metabolism are not sufficient to account for the different susceptibilities of these three plant species.