Good weed control is important in cotton production.
Weed management systems should prevent weed interference, be economical and sustainable, reduce weed seed bank in soil, prevent weed resistance and neither injure cotton, reduce quality, or lint yield. Weeds compete with cotton for moisture, nutrients, and sunlight. Weeds can reduce lint quality due to additional trash and staining of fibers leading to low grades and discounted prices. To be successful, weed management systems require advance planning and timely execution. Any delay in an application may mean reduced control, higher herbicide use rates, and greater herbicide costs.
A successful weed management plan will use multiple methods to keep weed populations low. Tillage and seedbed preparation should eliminate all emerged weeds prior to planting. Components of a weed management can include many of the following: 1) Early preplant burn-down which may contain a herbicide with residual activity; 2) Burn-down application at planting which may include a residual herbicide; 3) Post-emergence applications with or without a residual herbicide; 4) Post directed herbicides which may include a residual herbicide; 5) Lay-by herbicides; 6) Pre-harvest applications or defoliant and desiccant applications. The use of mechanical cultivation with rotary hoes, rolling cultivators, or sweeps may reduce the need for a herbicide application early in the growing season. Use of specific herbicides depends on the weed spectrum of your field, economic considerations and application system. Consider your situation and tailor a weed control program to your needs.
Weed Management Systems
Resources for Weed Management
Herbicide Resistance Management
Herbicide Mode of Action and Injury Symptoms - Univ. of Minnesota Extension
Cotton Herbicide Injury - Iowa State University
Cotton Pesticide Application
NCC Weed Resistance Learning Module
NCC 2007 Weed Resistance Bulletin
