Weed Control Systems for No-Till Cotton

R.M. Hayes, P.E. Hoskinson, and D.D. Tyler


 
ABSTRACT

Weed control systems for no-tillage cotton, Gossypium hirautum L., were evaluated in 1985 through 1987. Glyphosate, glufosinate, or sulfosate were more efficacious on horseweed, Conyza canadensis L., than paraquat; however, paraquat may provide acceptable preplant weed control in the absence of horseweed. When applied as preemergence tank mixtures with metolachlor plus fluometuron, glufosinate was more effective than either glyphosate or sulfosate. Early preplant applications of glufosinate or glyphosate followed by normal preemergence residual herbicides at planting were more effective than tank mixtures. Combining glufosinate (1.1 kg/ha) with metolachlor plus fluometuron (1.7 + 1.7 kg/ha) did not adversely affect the efficacy of glufosinate on horseweed, but residual herbicide activity, as determined by control of Palmer amaranth, Amaranthus Palmeri S. Wats., was reduced. Glufosinate rate could be reduced from 1.1 to 0.8 kg/ha by applying alone 14 days before planting without appreciable loss in activity. Combinations of glyphosate (1.1 kg/ha) with metolachlor plus fluometuron (1.7 +1.7 kg/ha) reduced the efficacy of both glyphosate and the residual herbicides. This antagonism was overcome by applying glyphosate 14 days before planting followed by residual herbicides at planting. Metolachlor and pendimethalin combinations performed similarly except on yellow nutsedge, Cyperus esculentus L., and spotted spurge, Euptorbia maculata L., where metolachlor combinations were more effective. The broadest spectrum residual activity was obtained where norflurazon (1.1 kg/ha) was included with metolachlor plus fluometuron or pendimethalin plus fluometuron combinations. Cultivation is usually not practical in no-till cotton; therefore, postemergence over-the-top or postdirected herbicides are often necessary to complete the weed control program for no-till cotton. There are numerous cost-effective herbicides available for postdirecting. Although initial herbicide costs are higher for no-till cotton, they are usually offset by lower labor, tillage, and cultivation costs,



Reprinted from 1988 Proceedings: Beltwide Cotton Production Research Conferences pg. 383
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998