Preplant-incorporated applications of commercial formulations of EPTC (S-ethyl dipropylthiocarbamate) and butylate (S-ethyl diisobutylthiocarbamate) plus the herbicide antidote R-25788 (N,N-diallyl-2,2-dichloroacetamide) were evaluated for their interactions with preemergence applications of tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} in corn (Zea mays L., ‘Pioneer 3780’) under greenhouse conditions. The thiocarbamate herbicides plus the antidote were used at 1.1, 2.2, 3.4, and 4.5 kg/ha, and they were evaluated against 0.3, 0.6, and 1.1 kg/ha of tebuthiuron. Shoot dry weight and shoot height of corn seedlings were measured at 24 days after treatment. Growth responses of corn to combination treatments of these herbicides were significantly reduced. Statistical analysis of the data showed that tebuthiuron interacted synergistically with both EPTC and butylate in the presence of the herbicide-antidote R-25788.

A location in east Central Kansas with a history of continuous corn (Zea mays L.), EPTC (S-ethyl dipropyl carbamothioate) plus dichlormid (2,2-dichloro-N,N-di-2-propenylacetamide) plus dietholate (O,O-diethyl O-phenylphosphorothioate) application, and shattercane [Sorghum bicolor (L.) Moench. #3 SORVU] was selected for herbicide efficacy investigations. Thiocarbamate herbicides applied before planting corn failed to control shattercane in 1 of 2 years. Adding dietholate did not improve EPTC efficacy in either year. Alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide] applied preplant failed to control shattercane both years. Treatments which included applications of alachlor at 2.2 kg ai/ha 7 or 10 days after preplant herbicide applications were made provided significantly better shattercane control than did preplant treatments.