A preliminary field study was conducted in 1985 with five growth regulators on cotton. The study was initiated at the Tennessee Valley Substation, Belle Mina, Alabama on a Decatur silt loam containing 1.5% organic matter. A randomized complete block design with 4 replications was utilized for this study. Rix, BC-2142, BC-2142-20, Burst, and Classic were applied at the pinhead square, early bloom, first bloom, and full bloom stages of cotton growth. Growth and yield evaluations were made using height measurements, node counts, boll counts, and yield information.

Cotton height was reduced 20% by Classic applied at the pinhead square stage of cotton growth. Other treatments were not found to be significantly different from the untreated check. All treatments averaged 4 to 5 nodes in the 9-15 inch range except for Classic applied at the pinhead square stage which increased the number of nodes in this range to 7. The average per cent of open bolls was 80% for most of the treatments. Classic applied at the pinhead square stage delayed boll opening 45% with an average of 35% open bolls. No significant differences were found for the first harvest yields. Pix and Burst averaged the highest first harvest yields with 2700 and 2600 lb/Ac seed cotton, respectively. Classic applied at the pinhead square stage provided the highest second harvest yield with 500 lb/Ac seed cotton. No significant differences were found for total cotton yield although a single application of Pix applied at the pinhead square stage provided the highest yield with 3400 lb/Ac seed cotton. Cotton was severely injured by Classic applications but recovered well after 2 to 3 weeks.