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Plant Monitoring Pays Cotton Growers Considering Plant Growth Regulator Use

The Issue

Safe and effective plant growth regulators are commonly applied to cotton during the growing season to help control excessively vigorous growth, increase yield and improve fiber quality. They have been used with success for more than 20 years in conventional Upland cotton grown in California and across the U.S. cotton belt. Pima cotton’s growth is especially vigorous and if left unchecked can result in significant loss of profit and crop quality. However, little growth-regulator research has been conducted on Pima cotton, which is prized for its long and strong fiber. Because of Pima's vigorous growth habit, long growing season and unique genetic background, growers need growth regulator guidelines designed specifically for this economically important crop.

What Has ANR Done?

UC researchers recently completed a five-year field study that identified specific plant growth conditions necessary for yield and quality enhancement by plant growth regulators, while under other conditions the same applications produced no benefit. The research confirmed the value of careful plant growth monitoring during the season. Monitoring helps the grower reduce unnecessary applications of growth regulators and also increases the likelihood of improved crop performance when the regulators are used. With proper growth regulator use, many Pima growers will choose to reduce the rate or the number of chemical defoliation treatments.

The Payoff

$50 to $100 more value per acre

When vigorously growing cotton plants were treated with two applications of a common plant growth regulator following first bloom, yield improvements ranging from 60 to 120 pounds per acre were observed. This translates into a $50 to $100 per-acre increase in crop value, with growers also reporting higher cotton quality grades and fewer problems with defoliation. When growers observed that monitoring did not favor a growth regulator application, they saved $15 to $20 per acre in application costs. Improved vigor management of Pima cotton has lead to a general reduction of chemical defoliant use.


Supporting Unit: Fresno County

Daniel Munk, UCCE Water, Soils and Cotton Farm Advisor, 1720 S. Maple Ave, Fresno, CA 93702,(559)456-7561 - dsmunk@ucdavis.edu

Robert B Hutmacher, Cotton Specialist, UC Shafter Research & Extension Center, 17053 Shafter Avenue,,Shafter CA, 93263, (661) 746-802 - rbhutmacher@ucdavis.edu