Weed Management Systems for Georgia Cotton

John W. Wilcut


 
ABSTRACT

Research was initiated in 1990 at Tifton to evaluate weed control, crop tolerance, and yields from the various components of weed management systems in Georgia cotton. In Experiment I, different combinations of preplant incorporated (PPI), preemergence (PRE), and post-directed (PDS) herbicides were evaluated. In Experiment II, different combinations of PPI and PRE herbicides were evaluated with 0, 1, or 2 cultivations or with a common PDS application. In Experiment I, treatments consisted of various combinations of PPI applications: pendimethalin at 0.75 lb ai/ac, pendimethalin plus norflurazon at 0.75 lb/ac; PRE applications of: fluometuron at 1.5 lb/ac, fluometuron+ fomesafen at 0.375 lb/ac, fluometuron+fomesafen+norflurazon at 0.75 lb/ac, or no PRE; and PDS applications of: nothing, fluoineturon at 1.5 lb/ac + MSMA at 2.0 lb/ac, methazole at 0.75 lb/ac + MSMA, or MSMA alone. In Experiment II, soil treatment options included pendimethalin PPI followed by a PRE application of fluometuron, fluometuron + fomesafen, or no PRE application; pendimethalin + norflurazon PPI followed by fluometuron PRE or norflurazon+fluometuron PRE. The aforementioned five soil treatment options were in a factorial arrangement with 0, 1, or 2 cultivations or a PDS application of fluometuron + MSMA. Deltapine 90 was used in both experiments. Data collected included visual estimates of weed control and herbicide injury, and seed cotton yield.

In Experiment I, all systems gave better than 90% morningglory (Ipomoea sp) species control except pendimethalin PPI (0%), pendimethalin PPI and Fluometuron + Fluometuron PRE (85%). Yellow nutsedge (Cyperus esculentur) control was at least 93% for allfomesafen containing systems. Equivalent control was provided by pendimethalin PPI and MSMA PDS and by pendimethalin + norflurazon PPI and fluometuron + MSMA PDS. Sicklepod (Cassia obtusifolia) control was greater than 91% for all norflurazon PPI containing systems, and fomesafen PRE containing systems. Only norflurazon PPI fomesafen PRE containing systems. Only norflurazon PPI systems provided excellent sicklepod control without a PDS applications. Systems providing highest yields without a PDS application included all fomesafen PRE systems.

In Experiment II, sicklepod control was increased with cultivation and with fluometuron + MSMA PDS. Soil applied treatments that gave excellent sicklepod control included pindimethalin + norflurazon PPI followed by fluometuron PRE or fluometuron + nor flurazon PPI followed by fluometruon PRE containing systems gave consistent excellent morningglory species control. Fomesafen PRE systems provided complete nutsedge control. Seed cotton yields were highest for cultivated or PDS systems.



Reprinted from 1991 Proceedings Beltwide Cotton Conferences pg. 962
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998