Effect of frequency and time intervention of insecticides on pink bollworm, Pectinophora gossypiella (Saunders) management in Bt cotton

Abstract

The study investigating the frequency and time intervention of different insecticide against pink bollworm in Bt cotton crops over two seasons during 2020-21 and 2021-22 was conducted at Entomology block, Main Agricultural Research Station, Raichur. Pooled data of both the seasons results noticed that the lowest pink bollworm larval incidence (2.00 larvae/ 10 bolls), green boll damage (11.78 %), bad opened bolls (14.10 %), locule damage (11.75 %) and highest good opened bolls (85.90 %) was documented in the treatment, T₁ with four sprays viz., profenofos 50 EC, chlorantraniliprole 18.50 SC, emamectin benzoate 5 SG and bifenthrin 10 EC at 65, 80, 95 and 110 DAS, respectively which showed on par with the treatment, T₉ with four sprays (profenofos 50 EC, chlorantraniliprole 18.50 SC, spinetoram 11.70 SC and fenpropathrin 10.00 EC at 65, 80, 95 and 110 DAS, respectively) and treatment, T₅ with ETL based spray (chlorantraniliprole 9.3+lambda-cyhalothrin 4.6 ZC) schedule. Similarly, highest cotton yield was obtained from the treatment, T₁ (17.89 q/ ha) which was on par with the treatment, T₉ (17.83 q/ ha) and T₅ (17.72 q/ ha). Whereas, the highest B: C ratio was obtained in treatment, T₁ (1.67) followed by the treatment, T₉ (1.57) and treatment, T₅ (1.54). This highlights effective strategic use of insecticides with varied mode of action, particularly, by following ETL-based sprays or administering four sprays at 15 days interval starting from 65 DAS, can efficiently control PBW infestation. This strategic method of application of insecticides at a particular frequency with time interval boosts seed cotton production by reducing pink bollworm incidence and its damage to Bt cotton with increased economic returns, emphasizing its practical viability for cotton cultivation.