Optimizing Insecticide Application: Evaluating Frequency and Timing for Effective Management of Pink Bollworm Infestation

Abstract

The pink bollworm (Pectinophora gossypiella), a significant pest affecting cotton crops, necessitates an optimized approach to insecticide application. This study investigates the critical factors of frequency and timing in insecticide application to enhance the efficacy of pest control measures. An experiment conducted at the Main Agricultural Research Station (MARS), University of Agricultural Sciences Raichur, focused on managing pink bollworm in Bt cotton using newer insecticides registered for cotton. Various spray frequencies and intervals were tested as part of an ETL (Economic Threshold Level) and prophylactic spray regimen. The results indicated that the treatment T1, which involved four sprays of profenofos 50 EC, chlorantraniliprole 18.50 SC, emamectin benzoate 5 SG, and bifenthrin 10 EC at 65, 80, 95, and 110 days after sowing (DAS), respectively, showed the lowest incidence of pink bollworm larvae, green boll damage, bad boll opening, locule damage, and the highest rate of good boll opening. This performance was comparable to treatment T5, which followed the same spraying schedule but with spinetoram 11.70 SC and fenpropathrin 10.00 EC instead of emamectin benzoate and bifenthrin, and treatment T9, which employed an ETL-based spray schedule using chlorantraniliprole 9.3 + lambda-cyhalothrin 4.6 ZC. Similarly, the highest yield of seed cotton was obtained from treatment T1 (18.10 q/ha), which was statistically equivalent to treatments T5 (18.12 q/ha) and T9 (18.10 q/ha). Additionally, the cost-benefit analysis revealed the highest benefit-cost ratio in treatment T1 (1.55), followed by treatments T9 (1.46) and T5 (1.44).