Chemical and physical removal of cotton fruit at insecticide termination to improve yields and control boll weevils

摘要

Increasing yields in cotton (Gossypium hirsutum L.) is an ongoing concern for many researchers. It has been shown that removal of upper-canopy squares at nodes above white flower five plus 350 heat units (NAWF=5+350 H.U.) may divert carbohydrates to developing bolls with a resulting yield advantage. This study evaluated different chemical and physical methods of removing late-season upper-canopy squares to potentially increase seedcotton yields and help control boll weevils (Anthonomus grandis). The research was performed in northeast and southeast Arkansas on an early-maturing Deltapine DP20B cultivar. To allow for any potential problems in the research due to weather and to provide two growth patterns, two planting dates were included in the study (early and mid May). The treatments for the 1999 season included a handsquare-removal and a mechanical topping treatment (physical removal), cyclanilide (Finish), ethephon (Prep), chlormequat (CCC), maleic hydrazide (M-H 30) (chemical removal) and a control with no fruit removal. The cotton products cyclanilide and ethephon were the most effective at removing unwanted upper-canopy fruit above NAWF=5 and helping to control boll weevils by limiting their late-season food sources. However, weight and fiber quality of first position bolls at NAWF=5 were decreased (P<=0.05) in plots treated with cyclanilide. The largest bolls were observed from the hand-square-removal and control treatments. No differences (P<=0.05) occurred with respect to increasing seedcotton yields, but the control unfortunately gave the highest numerical yields due to favorable late-season growing condition and maturation of upper bolls not removed by the control treatment.