ABSTRACT

Mirid bugs are prominant pests of cotton presently. The substantial symptoms and damage inflicted by mirid bugs lead to significant economic losses to the cotton crop. Higher infestation of mirid bugs with 5.10 bugs/5 squares and square shedding (1.90 squares/plant), boll shedding (1.54 bolls /plant), parrot beaked boll (3.14 bolls/plant) and boll with scar (4.37 bolls /plant) were observed in fields at Haveri district during a survey conducted in 2023. In Dharwad district the incidence of mirid bugs was 3.88 bugs/5 squares with (1.02) shedding of squares. Ten different Bt and non Bt cotton cultivars were studied for infestation pattern and damage by mirid bugs through a field study at MARS, Dharwad during 2023. The incidence of mirid bug was noticed from September II FN and gradually increased in October and peak incidence was noticed in the II FN of November in all genotypes except DDhC-11 and DLSa – 17 N Bt. The highest infestation was observed in November II in DHH-11 non Bt (14.21 bugs/10 squares) leading to 19.68 per cent square shedding. Suvin non-Bt had lowest (6.00 bugs/10 squares) incidence 9.04 per cent square shedding. NBC -3 Bt had higher yields (19.21 q/ha) in unprotected condition. Among eleven different insecticides tested in field bio-efficacy against mirid bugs at MARS Dharwad (2023) Acephate 50 + Bifenthrin 10 WDG @ 1.0 g/l found to be highly effective with only 2.56 bugs/10 squares of mirids and least shedding (2.42%) of squares and (5.59%) boll damage. The seed cotton yield in this treatment was 2.91 q/ha with 2.91 B:C ratio. Other insecticides with good bio-effecicay were Fipronil 5 SC, Fipronil 4 + Acetamiprid 4 SC, Acephate 75 SP, Profenophos 50 EC and Profenophos 40 + Fenpyroximate 2.5 SC in the order with B:C ratio of 2.87, 2.83, 2.72, 2.69 and 2.63, respectively.