Pest pressure is considerably greater in the Imperial and Palo Verde valleys. Pink bollworm is a significant problem in these areas, but has been mitigated somewhat by the mandatory short season that breaks the insect's reproductive cycle. Another serious cotton pest in the Imperial Valley is the sweet potato whitefly. Once established, cotton can hold its own against weeds. A program of rotation, preirrigation and timely cultivation can keep hand labor costs to a minimum.
Mechanical harvesting requires relatively weed-free fields.
The biggest question for California organic cotton producers is how to defoliate the crop prior to harvest. Under conventional production practices, this is accomplished using synthetic chemicals. While it is possible to mechanically harvest cotton without defoliation, it is more difficult than with defoliation and can reduce quality by several grades. The presence of foliage results in a higher moisture content of the harvested cotton, which in turn requires greater care and attention during the drying and ginning process. In some cases the decomposition process may produce temperatures in excess of 130 F. Additionally, San Joaquin Valley growers are required to plow down their crop residue by December 20 for pink bollworm control.