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United States Department of Agriculture - page 27 / 36





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SAMPLE PETITIONHerbicide-Tolerant Plants

application methods were devised.

In the various cotton-growing regions of the country, cotton producers manage weeds differently. The following summarizes typical practices for the mid-South region (Frans and Chandler 1989).

  • 1.

    Disk twice and broadcast and incorporate trifluralin before planting.

  • 2.

    At planting, apply fluometuron preemergence on bands.

  • 3.

    Cultivate and postdirect fluometuron plus MSMA on bands.

  • 4.

    Cultivate and postdirect prometryn plus MSMA on bands.

  • 5.

    Spot spray with fluazifop.

  • 6.

    Cultivate and postdirect cyanazine on bands.

  • 7.

    Hand hoe, cultivate, and postdirect dinoseb on bands.

Recently yields of cotton lint have declined, and continued herbicide use is strongly implicated, especially where cotton is grown continuously and the same herbicides are applied yearly (Frans and Chandler, 1989). Rogers et al. (1985, 1986) summarized results from a long- term experiment in which herbicides were applied to cotton at different levels for 6 to 7 years. No reduction in cotton yield occurred following continuous use of a minimum set of herbicide practices. When intensive practices were used (trifluralin preplant incorporated, fluometuron preemergence, two postemergence directed applications of fluometuron plus MSMA, and linuron applied at last cultivation), yields dropped on average up to 8 percent. Of the rotation crops planted on these areas, corn and sorghum suffered the least damage while soybeans and rice were severely injured.

Herbicide residues in the cotton crop have also been a concern, especially those of organic arsenicals. Both DMSA and MSMA are used postemergence for control of


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