Harvest-aid chemicals (HACS) and plant growth regulators (PGRS) are widely used by cotton producers to manage plant development, crop termination and harvest scheduling. A Beltwide survey was conducted in 1990 by state universities and the USDA under the National Agricultural Pesticide Assessment Program (NAPIAP). The assessment provided a national data based on: (1) use patterns of HACs and PGRs (rates, application timing, acreage treated); (2) non-chemical options that could be substituted for HACs and PGRS; (3) impact of cancellation of individual products on yield, secondary factors such as fiber quality and the use of alternative chemical and non-chemical options; and (4) the impact of the loss of entire chemical groups (i.e. defoliants) on yield, secondary factors and utilization of alternative practices. Extension cotton specialists in 14-states were requested to provide the above information for their respective states.

The products included in the survey were: (1) defoliants - Def/Folex, Dropp, Sodium Chlorate, Accelerate, Harvade, Bolls-Eye (sodium cacodylate) and Cotton Aide (cacodylic acid) ; (2) PGRs - Pix and Prep; and (3) desiccants - arsenic acid and paraquat. The survey indicated that approximately 84%, 74% and 7%, respectively, of the U.S. cotton acreage was treated with defoliants, PGRs and desiccants, respectively.

Non-chemical alternatives for the HACs included waiting for a frost/freeze; picking untreated cotton, nitrogen management, use of early-determinate varieties, and discontinuing cotton production. Alternatives for PGRs were: early season insect control, earlier planting and selection of faster maturing varieties.

Projected yield losses (nationwide) due to cancellation of individual chemicals with use of alternative chemical and non-chemical practices ranged from 1.7 to 1.8% for the PGRS, 0.2 to 1.7% for the desiccants and 0.02 to .73% for the defoliants. Without use of the alternatives, potential losses were 1.8 to 2.7% for the PGRS, 2.1 to 2.9 for the desiccants and 0.02 to 4.8% for the defoliants. Secondary impacts due to the loss of individual HACs and PGRS included reduced lint quality, delayed harvest, overall increase in production costs, reduced effectiveness of harvest-aid treatments, lower harvester efficiencies and less effective insect and disease control. Where chemical alternatives exist, the survey indicated other products (though less effective) would be used to replace those lost. Frost/Freeze was the dominant non-chemical alternative for a cancelled HAC.

Potential yield losses due to cancellation of product groups with use of alternative chemical and non-chemical options were 16.8% for the defoliants and paraquat, 4.9% for the PGRs and 1.3% for arsenic acid. Without use of the alternatives, potential losses increased to 6.8% for defoliants and paraquat, 6.8% for PGRs and 2.3 for arsenic acid. Secondary impacts included reduced fiber quality, delayed harvest, increased production costs, more disease and insect problems, reduced harvester efficiencies and a reduction in cotton acreage. Waiting for a frost/freeze was identified as the primary nonchemical option for loss of HAC groups.