Waterhemp Control in Transgenic and Conventional Corn Varieties
2004
Sellers, Brent A. | Cordes, Joseph C. | Smeda, Reid J. | Johnson, William G.
Common waterhemp has become a major problem in the western corn belt. Recent surveys in Missouri indicate that waterhemp is the number one problem weed in corn production. To determine the most effective herbicide combinations and application timings in transgenic and conventional corn varieties for waterhemp control, experiments were conducted at three locations over two years. In general, all herbicide strategies provided excellent waterhemp control within five weeks after the last herbicide application. In Roundup Ready, Liberty Link, and Clearfield herbicide programs, waterhemp density in the middle of August was at least 1.8-fold lower using a preemergence application of atrazine plus acetochlor followed by the appropriate postemergence herbicide strategy for each program in all site-years, except in one instance. With conventional corn varieties, waterhemp densities were similar among herbicide programs. In only one site-year, corn yields in the late-postemergence herbicide strategy were at least 10% lower than the other three herbicide strategies in transgenic corn. In conventional corn, the 1-X preemergence followed by mid-postemergence applications of herbicides resulted in 14% greater grain yields, but only under irrigated environments. These data suggest that waterhemp can be controlled using various approaches in both transgenic and conventional corn varieties.
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