Use of harvest aids to terminate and prepare the cotton crop for machine harvest has been an accepted practice for expediting crop maturity, increasing harvest efficiency, and improving lint yield and quality. Many materials have been registered and recommended for use as harvest aids in the United States. Aim, CottonQuik, Def/folex, Dropp, Finish, Ginstar, Harvade, and Prep/ethephon are some of the most popular products currently in use. New products come onto the market continually and are tested. Some products become quite popular and others do not. Proper use of these products is important to ensure the quality of defoliation, boll opening, and regrowth control. However, variability of growing conditions during the season, different varieties, cultural systems used, and environmental factors during the harvest all combine to result in no standard method for harvest aid timing or choice of materials (Patterson and Smith, 2001). Although not exact, timing of harvest aid application is generally guided by such techniques as percent open bolls, the cut boll technique, and nodes above cracked boll (Banks, 2001). Choice of harvest aids varies with production region, type of harvest, physical and environmental factors. Nevertheless, most growers use mixtures popular in their area to accomplish some or all of the following actions: defoliation, boll opening, regrowth control, and desiccation in the case of stripper cotton. Obviously, evaluation of a harvest aid alone or in combination with others is extremely important for identifying the optimal rate for the product and/or combinations of products.

Picker cotton is usually treated with a hormonal or herbicidal defoliant to remove leaves, while stripper cotton is treated with defoliant followed by a desiccant or simply with a once-over desiccant in low yielding fields (Cothren and Witten, 2001; Keeling, 2001). Both hormonal and herbicidal defoliants injure the leaf by increasing ethylene production that causes the leaf to fall from the plant, while desiccants are harsher than defoliants, these cause injury that leads to rapid moisture loss and drying of the leaves.

As there is great variability of growing conditions during the season and many alternative cultural practices, there is also great variability in the cost of various harvest aid programs. The objective of this study is to analyze data from six years of defoliation tests to determine if generalizations can be drawn regarding a best management practice.