DEFOLIATION TRIAL COMMENTS                               

By: Kent Taylor 

2002 DEFOLIATION PROJECT SUMMARY (IRRIGATED COTTON)

Trials were established at 5 locations to evaluate defoliants. Locations were selected by consultants and treatments were selected by participating company representatives. Applications were made daily in a 5 day period beginning on September 30 and ending on October 4. Ratings were made at 7 and 14 days following treatment application. The tests were scheduled to have started 2 weeks earlier but inclement weather forced their postponement. Therefore, cotton at the test sites was more mature than first planned. Locations are discussed individually as follows:

BLECKLEY COUNTY (Spray Date: 9/30 - Consultant: Michael Williams) Cotton at this site was 90% - 95% open at 7 days after application and foliage was mostly mature. Defoliation ranged from 70% - 90%. No appreciable desiccation was observed but new growth had started in some treatments. At 14 days after application, new growth increased in many treatments and defoliation ratings were mostly less. Percent open bolls had increased to 95% - 100% and desiccation was no longer evident.

DOUGHERTY COUNTY (Spray Date: 10/1 – Consultant: Carl Hobbs) Treatments at this site received heavy drift from an adjacent aerial application and no meaningful ratings could be taken.

SEMINOLE COUNTY (Spray Date: 10/2 – Consultant: Wes Briggs) Cotton at this site was judged to be 80% - 95% open at 7 days after application and foliage was mostly mature. Defoliation ranged from 75% - 90%. Up to 10% desiccation was noted in some plots and some new growth had appeared in others. At 14 days following application, desiccation had pretty much vanished but new growth was highly evident in many treatments. Defoliation ratings had improved slightly in a couple of treatments but were either no better or worse in the remainder. Bolls open at 14 days ranged from a low of 85% in one treatment to a high of 100% in two others. Most were 90%-95% open.

BACON COUNTY (Spray Date: 10/3 – Consultant: John Beasley) Cotton foliage at this site was mostly mature and was about 90% open at 7 days after application. Except for a few dominant plant terminals, which may not have received a full measure of spray, defoliation was good to excellent. All treatments were exhibiting at least 85% defoliation and green leaves remaining did not exceed 10%. At 14 days following application, all desiccation had disappeared and all treatments had maintained at least 85% defoliation. Bolls open had increased to 95% - 100%.

BULLOCH COUNTY (Spray Date: 10/4 – Consultant: Mike Gomez) Cotton at this location was lush and green with plants still actively fruiting. However, boll opening at 7 days after application was about 90% in all treatments. Defoliation at 7 days was unsatisfactory with all treatments with none exceeding 65%. Also, desiccation with some treatments was up to 20%. At 14 days there was not much improvement. Desiccation ratings were down but new growth ratings were mostly up resulting in little or no improvement in % green leaves remaining. Defoliation ratings still ranged from a low of 30% to a high of 75% at this location.

NOTE: Although not statistically different, there are some major differences in performance in some trials. Over 10% green leaves remaining or over 10% desiccation remaining would be unacceptable by most standards.

Treatment  

(and Rate per Acre)