Performance of Six Substituted Dinitrobenzamine Herbicides Applied at Layby of Cotton (Gossypium hirsutum)

Abstract

Six substituted dinitrobenzamine herbicides, including butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine], dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], and trifluralin (α,α,α,-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), were evaluated as directed broadcast sprays applied and soil incorporated at time of last cultivation (layby) of cotton (Gossypium hirsutumL. ‘Acala SJ-2’). At the rates used, all herbicides provided more than 90% control of annual grasses. During 1976 and 1977, control of redroot pigweed (Amaranthus retroflexusL.) and smooth pigweed (Amaranthus hybridusL.) ranged from 90 to 100% and none of the herbicides differed significantly in their effect. However in 1975, butralin at 1.1 kg/ha did not improve pigweed control when compared to the untreated control. None of the herbicides consistently controlled black nightshade (Solanum nigrumL.) and except pendimethalin, none caused detectable cotton injury. In 2 of 3 yr, pendimethalin caused enlarged growth of the cotton stem in the cotyledonary node area contacted by the herbicide spray. Stem breakage following wind occurred in about 5% of the cotton plants; however, the injury was not manifested by reduced yield. None of the herbicides influenced cotton yield. Residues from soil samples collected 4 months after herbicide application reduced growth of Japanese millet [Echinochloa crus-galli(L.) Beauv. var.frumentacea(Link) Wright]3and grain sorghum [Sorghum bicolor(L.) Moench] 24 to 49%.