Tolerance of Cotton (<i>Gossypium hirsutum</i>) Seedlings to Preemergence and Postemergence Herbicides with Four Modes of Action

Abstract

The current dominant weed control program in cotton relies heavily on glyphosate. Typical glyphosate-based weed control programs require repeat applications. A residual herbicide might reduce the number of herbicide applications needed, and potentially reduce costs. Residual herbicides that can be used postemergence in cotton are limited in number, and there are few studies evaluating the response of cotton to over-the-top application of herbicides. A greenhouse study evaluated response of cotton to fluometuron, propazine, metolachlor, pyrithiobac, and glyphosate. Most of these herbicides caused minimal crop injury; however, fluometuron and propazine caused significant visual injury when applied over-the-top at the cotyledon and two-leaf stages, but less injury when applied preemergence. Accepted for publication 5 July 2007. Published 8 November 2007.