Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 4, 1999
Publication Date: N/A
Interpretive Summary: Producers are concerned that the cost of using Roundup-resistant cotton may not be worth the extra expense of seed plus a $9/acre technology fee. This study compared six herbicide treatments over a three-year period. The first two treatments were conventional moldboard tillage and mechanical cultivation, a preemergence herbicide with and without postemergence herbicides. The next two treatments were no-tillage using postemergence herbicides with and without a preemergence herbicide combined with in-season, between-row mechanical cultivation. The next two treatments included Roundup applied at the four-leaf stage of cotton and again in a hooded sprayer later in the season with and without a preemergence herbicide. Yields were not statistically different over the three-year period but the lowest production costs and greatest net returns were with treatments which included Roundup applied to the four-leaf stage of cotton and again later in a hooded sprayer. Under heavy weed pressure the Roundup-resistant cotton weed management system, when used in combination with no-tillage, had the fewest trips over the field, lowest input costs and greatest net returns which more than offset costs associated with the seed and technology fees for Roundup-resistant cotton.
Technical Abstract: The release of Roundup-resistant cotton has opened new options for producers to manage postemergence weed problems. Producers are concerned with the high costs of the new technology and whether or not the economic returns are worth the risk of adopting the new technology of using Roundup- resistant cotton. Objectives of the study were to compare six weed management treatments over a three-year period for effects on cotton lint yields and production economics. The same seed (Variety Paymaster 1220 RR) was used for all treatments, but the additional seed costs and technology fee were charged only to the treatments which included postemergence Roundup in the weed management program. Two of the treatments included conventional tillage, preemergence herbicides, with and without postemergence herbicides, and mechanical cultivation during the growing season. Two treatments were no-tillage, with and without preemergence treatments. Two treatments were no-tillage and included postemergence Roundup with and without a preemergence herbicide. Average lint yields ranged from 471 lbs/acre to 581 lbs/acre, but were not statistically different among treatments. The greatest net returns of $200/acre were with no-tillage using preemergence application of Prowl, Roundup postemergence broadcast at the four-leaf stage of cotton and later in the season applied with a hooded sprayer. Net returns using this no-tillage technology system were $87/acre greater than the conventional tillage treatment of moldboard tillage using a preemergence application of pendimethalin, postemergence application of fluazifop plus mechanical cultivation twice during the growing season.