Boll Maturation and Defoliation. The synthetic growth regulators and defoliants used for conventionally grown cotton are not approved for use in organic cotton production. Growers instead rely on nutrient and water management to assist in boll maturation, opening and plant defoliation. For example, growers supply only enough nitrogen to insure fruit set and boll development on a yearly basis. Overfertilization or excessive soil nitrogen promotes vegetative growth and discourages boll maturation.
Zinc sulfate is foliar-applied to assist in boll maturation and opening.
A soil or plant deficiency in either zinc or sulfur must be demonstrated before this material can be applied. Also, water is cut off early in the season in an attempt to stress plants and aid in defoliation. While helpful, these techniques do not always achieve the same results as the synthetically formulated materials. In cases where a low level of defoliation is attained, harvest may be slowed and cotton grades reduced, with trash levels and ginning costs increased. Harvest and Ginning.