Acetanilide-Antidote Combinations for Weed Control in Corn (Zea mays) and Sorghum (Sorghum bicolor)

Abstract

R-25788 (N,N-diallyl-2,2-dichloroacetamide) and H-31866 [N-allyl-N-(3,3-dichloroallyl)dichloroacetamide] were more effective than CDAA (N,N-diallyl-2-chloroacetamide) in preventing yield reductions to corn (Zea maysL. ‘NB-611’) from alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] or metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] in the greenhouse. A CGA-43089 [α-(cyanomethoximino)-benzacetonitrile] seed treatment (1.25 g/kg) was more effective than a R-25788 tank mix in preventing yield reductions to grain sorghum [Sorghum bicolor(L.) Moench ‘G-623 GBR’] from alachlor or metolachlor in the greenhouse. Absorption of14C-alachlor by sorghum seedlings grown in petri dishes, and absorption, translocation, and metabolism of14C-metolachlor by sorghum seedlings grown in soil, were not affected by CGA-43089 seed treatment. Forage sorghum [Sorghum bicolor(L.) Moench ‘Rox Orange’] was used to simulate shatter cane [Sorghum bicolor(L.) Moench] in field plots. In the absence of Rox Orange, alachlor and metolachlor reduced sorghum grain yields. This yield reduction was prevented by a CGA-43089 seed treatment, but not by a R-25788 tank mix with herbicides. In plots seeded with 10,000 Rox Orange seed/57 m2, grain yields of sorghum increased as alachlor or metolachlor plus CGA-43089 rates increased. There was no grain yield response to any herbicide treatment in plots seeded with 50,000 Rox Orange seed/57 m2.