Antagonistic Responses with Combinations of Carbamate and Growth Regulator Herbicides

Abstract

Antagonistic responses were noted on sorghum (Sorghum vulgarepers.) and giant foxtail (Setaria faberiiHerrm.) using preemergence combinations of (2,4-dichlorophenoxy)acetic acid (2,4-D) and the carbamatesS-ethyl dipropylthiocarbamate (EPTC), isopropylm-chlorocarbanilate (chlorpropham), and 2-chloroallyl diethyldithiocarbamate (CDEC). Combinations of EPTC and (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T) or 3,6-dichloro-o-anisic acid (dicamba) gave similar results. Effects of these combinations were mainly additive on four dicotyledonous species. Combinations of 2,4-D andN-1-naphthylphthalamic acid (naptalam) also were antagonistic on sorghum and giant foxtail but were additive on the remaining species. Eight other herbicide combinations were mainly additive on all six species.