Harvest-aid application decisions need to be based on crop maturity, crop condition, weather conditions, and desired harvest schedule. Once producers decide that defoliation is needed, they must determine when the chemical should be applied, what material(s) will be applied, and how much material(s) to apply.

Crop Condition

Defoliation, whether natural or chemically induced, is a physiological process that requires a certain amount of plant activity, thus crop condition is a main factor in determining the response to defoliants. Chemical induced defoliation can be best accomplished in a mature, well fruited, uniform crop which is showing signs of "cut-out". In season management have a significant inpact on defoliation success.

Weather

Weather conditions prior to and up to three or four days following defoliation application have a great affect on the plant response to defoliants. Defoliants are most active when temperature, sunlight intensity, and relative humidity are high. A nightime temperature of 60 degrees F or lower greatly reduces the activity of most defoliant products. Air temperatures will largely determine the selection of defoliation materials and rates. Still, desired defoliation materials and rates of application often change during the season with changes in crop condition and weather.

Harvest Schedule

To develope an effective harvest scheduling plan, growers should consider; The number of acres to be harvested, Cotton Picker Capacity (total acres per day harvested), The number of picking days available and Crop maturity. By taking these factors into consideration a producer can determine which fields to defoliate first and how much to defoliated depending on picker capacity. Applications should be timed so that harvesting can keep up with defoliation. In general, defoliate only as much acreage as can be harvested in about 12 days. Early defoliation of excess acreage can decrease yields, expose lint to weather more than necessary, and increase the likelihood of significant regrowth. The need for materials to aide with boll opening and/or regrowth inhibition may change during the season once harvest has begun. In the end, the two most important factors in determining when to defoliate are crop maturity and desired harvest schedule.