Comparisons of HOE-39866, SC-0224, Paraquat, and Glyphosate in No-Till Corn (Zea mays)

Abstract

Field studies were conducted for 4 yr with HOE-39866 [ammonium-(3-amino-3-carboxypropyl)-methylphosphinate] and for 2 yr with SC-0224 (trimethylsulfonium carboxymethylaminomethylphosphonate) to compare foliar activities with those of paraquat (1,1’-dimethyl-4,4’-bipyridinium ion) and glyphosate [N-(phosphonomethyl)glycine] in no-till corn (Zea maysL. ‘Pioneer 3320’ in 1981 and ‘Pioneer 3184’ in 1982 and 1983). Rates evaluated were 0.6 to 1.7 kg ai/ha for all herbicides except paraquat which was included at 0.3 and 0.6 kg ai/ha. Control of rye (Secale cerealeL.) was excellent at all rates with SC-0224, paraquat, and glyphosate, but HOE-39866 was effective only when combined with residual herbicides. All four herbicides provided good initial control of horseweed [Conyza canadensis(L.) Cronq., ♯ ERICA], but recovery following paraquat application was extensive. Combinations of HOE-39866, SC-0224, and glyphosate at 0.6 kg/ha with atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 1.1 to 1.7 kg ai/ha + metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] at 1.7 kg ai/ha produced antagonistic responses against rye and sometimes horseweed. In 1983, the combination of SC-0224 + residual herbicides provided significantly better control of rye and horseweed 8 days after treatment than the combination of glyphosate + residual herbicides.