Germination Stimulation Properties of Carbamate Herbicides

Abstract

Butylate (S-ethyl diisobutylthiocarbamate), EPTC (S-ethyl dipropylthiocarbamate), vernolate (S-propyl dipropylthiocarbamate), diallate [S-(2,3-dichloroallyl)diisopropylthiocarbamate], CDEC (2-chloroallyl diethyldithiocarbamate), and chlorpropham (isopropylm-chlorocarbanilate) at 0.1 kg/ha caused increased velvetleaf (Abutilon theophrastiMedic.) populations in field plots. Butylate caused increased populations of common lambsquarters (Chenopodium albumL.) at rates of up to 1.1 kg/ha. In the laboratory, each of the six herbicides caused increased velvetleaf seed germination, and butylate, EPTC, and CDEC caused increased common lambsquarters germination when seeds were exposed to herbicide vapors prior to germination. Germination of velvetleaf, common lambsquarters, and giant foxtail (Setaria faberiiHerrm.) was also increased by butylate solutions over a wide range of concentrations. Maximum germination stimulation generally occurred between concentrations of 10-5and 10-6M butylate. Seedling injury and death also resulted from these concentrations of butylate. Butylate stimulation of seed germination could not be correlated with light requirements of seeds, but appeared to be an additional promotive factor. Ungerminated common lambsquarters seeds after butylate treatment were viable and responded to KCN and KNO3in the same manner as control seeds which did not initially germinate in water. Butylate in combination with the antidote, R-25788 (N,N-diallyl-2,2-dichloroacetamide) stimulated germination of common lambsquarters.