Optimizing Herbicide Activity for Weed Control in No-Tillage Cotton

Gregory A. Mitchell and Robert M. Hayes


 
ABSTRACT

Weed control in no-tillage cotton (Gossypium hirsutum L.) relies on herbicides. Studies were conducted in 1987 and 1988 to optimize the efficiency of herbicides in no-tillage cotton. These included 'burndown' herbicides, soil-applied residual herbicides, postdirected herbicides, and postemergence over-top applications of DPX-T9595. Glyphosate (0.8 kg/ha), glufosinate (0.8 kg/ha), sulfosate (1.1 kg/ha), paraquat-diuron (0.8 kg/ha), and glyphosate + 2,4-D (0.6 + 0.6 kg/ha) provided better control of horseweed [Conyza canadensis (L.) Cronq.] than paraquat (0.4 or 0.6 kg/ha) alone. Glufosinate provided excellent control of crimson clover (Trifolium incarnatum L.), hairy vetch (Vicia villosa (L.) Roth) and wheat (Triticum aestivum L.) while only wheat was controlled with paraquat, glyphosate, sulfosate, and glyphosate + 2,4-D. Sequential applications of early preplant herbicides followed by preemergence residual herbicides were more effective than applications as tank-mixtures. Metolachlor or pendimethalin in combination with fluometuron or fluometuron plus norflurazon provided acceptable early season weed control, but a postemergence herbicide was normally required to control escaped weeds. Post-directed methazole, (0.8 kg/ha and 1.0 kg/ha) prometryn, (0.6 kg/ha) or cyanazine (0.8 kg/ha) in combination with MSMA (2.2 kg/ha) afforded excellent season-long control of morningglory (Ipomoea spp.) while oxyfluorfen, (0.6 kg/ha) plus MSMA (2.2 kg/ha), lactofen (0.2 kg/ha) plus MSMA (2.2 kg/ha) or lactofen (0.2 kg/ha) provided initial control, but reinfestation soon occurred. Methazole plus MSMA (1.1 kg/ha + 2.2 kg/ha) controlled prickly side (Sida spinosa L.) while other postdirected treatments did not Drovide adequate control. Methazole (2.1 kg/ha), oxyfluorfen (0.6 kg/ha), lactofen, (0.2 kg/ha) prometryn (0.6 kg/ha) or cyanazine (0.8 kg/ha) in combination with MSMA (2.2 kg/ha) gave good to excellent control of smooth pigweed, (Amaranthus hybridus L.) and palmer amaranth (amaranthus palmeri L.) while methazole plus MSMA (0.8 kg/ha + 2.2 kg/ha) and lactofen (0.2 kg/ha) did not control these species. DPX-T9595 controlled common cocklebur, (Xanthium strumarium L.) and morningglory, but did not control pigweed, lambsquarter, (Chenipodium album L.), prickly side and sicklepod (Cassia obtusifolia L. ) , but when used in conjunction with preemergence and post-directed herbicides satisfactory control of these weeds was achieved.



Reprinted from Proceedings: 1989 Beltwide Cotton Research Conferences pg. 388
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998