Farmers had initiated indiscriminate use of insecticides against pink bollworm and incurred high cost of managing. Unless extension initiatives to create awareness to manage pink bollworm, the situation may further lead to yield losses, distress of cotton farmers and threat to sustainability that in turn will have a cascading effect on textile industries and economy. Keeping in view, pink bollworm management strategies comprising of timely sowing, use of refuge, recommended nutrition, monitoring through pheromone traps, release of bio-control agent, recommended insecticide sprays at ETL, field sanitation and timely termination of the crop formulated by ICAR-CICR, Nagpur were disseminated and demonstrated to 50 beneficiary farmers in irrigated tract of Valia taluka of Bharuch district. Amongst sucking pests population, aphid, thrips and leafhopper had crossed ETL once and whitefly and mealybug remained below ETL during the season in IRM-FLD plots whereas aphid, thrips and leafhopper crossed ETL 4, 1 and 5 times, respectively whereas whitefly and mealybug remain below ETL during the season in non-IRM plots. Sucking pests required average 2.90 sprays in IRM-FLDs plots whereas slightly higher 3.00 in non IRM plot. For pink bollworm management, 2.20 and 2.70 sprays were targeted by farmers under IRM and non-IRM plots condition, respectively. Seed cottonyield varied from 830 to 979 kg/acre and from 810 to 968 kg/acre under IRM and non IRM condition, respectively. The net return was found higher in IRM plots (Rs. 21,500 to 27,875/acre) than the non IRM (Rs. 18,740 to 25,663/acre). The FLDs and outreach extension activities aided in educating and percolating technology to adjacent periphery of the region.
Investigations on the population dynamics of aphid Aphis gossypii Glover on Bt (G.Cot.Hy.8 BG II) and non-Bt (G.Cot.Hy.8) were carried out at Main Cotton Research Station, Navsari Agricultural University, Surat, Gujarat during the Kharif, 2020-21. The incidence of aphids initiated in the first week of July (27th SW) in Bt cotton hybrid and in the second week of July (28th SW) in non-Bt cotton hybrid and continued till the crop harvest in the second week of January (2nd SW) in both the hybrids. The peak activity of aphids was recorded during the third week of December (51st SW) in Bt as well as non-Bt cotton hybrid. In both Bt and non-Bt cotton, the aphid population had a significant negative correlation with morning relative humidity. There was a highly significant negative correlation with minimum temperature, evening relative humidity, rainfall, rainy days, and a positive correlation with sunshine hours.
Investigations on toxicity of insecticides against cotton thrips (Thrips tabaci Lindeman) was carried out at laboratory of Main Cotton Research Station, Navsari Agricultural University, Surat during August to October 2020 through the IRAC leaf dip bio-assay technique. Thrips population from the farmer’s field of Bharuch district were collected and reared at Main Cotton Research Station, NAU, Surat under field cage cover. Leaf dip bio-assays were carried out for the five insecticides viz., fipronil 5 SC, buprofezin 25 SC, diafenthiuron 50 WP, profenophos 50 EC and imidacloprid 17.8 SL with eight concentrations. At recommended rate, diafenthiuron 50 WP at 0.06% and profenophos 50 EC at 0.1% recorded 90.36 and 83.29% mortality of thrips at 72 hours after exposure. Buprofezin 25 SC at 0.05%, imidacloprid 17.8 SL at 0.00445% and imidacloprid 17.8 SL at 0.00445% recorded 79.81, 63.54 and 57.06% mortality of thrips under laboratory bioassay at 72 hours after exposure. The recommended rate of the test insecticides except fipronil 5 SC and imidacloprid 17.8 SL did not show much variation in susceptibility at 72 hours after exposure.
Investigations on susceptibility of insecticides in cotton mealybug (Phenacoccus solenopsis Tinsley) was carried out at Main Cotton Research Station, Navsari Agricultural University, Surat during October 2020 to January 2021 through the IRAC leaf dip bio-assay technique. Mealybug population from the farmer’s field of Bharuch district were collected and reared at Main Cotton Research Station, NAU, Surat under field cage cover. Leaf dip bio-assays were carried out for the seven insecticides viz., imidacloprid 70 WG, acetamiprid 20 SP, thiamethoxam 25 WG, buprofezin 25 SC, lamda cyhalothrin 5 EC, spinosad 45 SC and profenophos 50 EC with eight concentrations including control with three repetitions. At recommended rate, profenophos 50 EC at 0.1% and acetamiprid 20 SP at 0.004% recorded 83.50 and 80.77% mortality of mealybug after 72 hours of exposure. Buprofezin 25 SC at 0.05% recorded 78.89 while imidacloprid 17.8 SL at 0.00445% exhibited 67.70 and thiamethoxam 25 WG at 0.01% found to show 65.91% mortality of mealybug under laboratory bioassay after 72 hours of exposure.
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