ABSTRACT

Field experiments were conducted in 2002 near Corpus Christi (Coastal Bend) and Weslaco (Rio Grande Valley), TX to evaluate the effectiveness of insecticides on the cotton aphid (Aphis gossypii Glover). Insecticides tested included flonicamid (F1785 50DF), imidacloprid (Trimax 4F), carbofuran (Furadan 4F), acetamiprid (Intruder 70 WP), thiamethoxam (Centric 40WG), dicrotophos (Bidrin 8E), and cyfluthrin + imidacloprid (Leverage 2.75 SE). Information is presented on aphid numbers, plant damage ratings, and lint yield. Damage ratings and lint yield are reported only from the Coastal Bend field study. All insecticides except Bidrin (Coastal Bend tagged leaf data) and Leverage (Rio Grande Valley) significantly reduced aphid numbers on each inspection following treatment through 8 days after treatment (DAT) in the Rio Grande Valley study and 20 DAT in the Coastal Bend study. In the Coastal Bend study, aphid counts from terminal leaf data in the Bidrin treatment were not significantly different from untreated cotton on any inspection date. Additionally, aphid counts on terminal leaves in the Trimax and Furadan cotton were not significantly different from untreated cotton on inspections 12 and 15 DAT. Intruder and Centric were the most consistent in reducing aphid numbers in both experiments. In the Coastal Bend experiment visual plant damage ratings correlated directly with aphid counts. Insecticide treated cotton (Coastal Bend) averaged 71 lb lint/acre more than untreated cotton. The Intruder and high rate of Centric treatments produced significantly greater lint yield than the untreated cotton (208 lb/acre average).