Dr. K. DEVAKIPODILI VENKATA LAKSHMI PRAVALIKA2024-03-272024-03-272024-03-27D6537https://krishikosh.egranth.ac.in/handle/1/5810207752The present investigations on “Studies on persistence of certain seed treatment pesticides in groundnut against sucking pests” were carried out in Department of Entomology, Pesticide Residue Laboratory, Institute of Frontier Technology (IFT), Regional Agricultural Research Station (RARS), Tirupati and College Farm, S.V. Agricultural College, Tirupati during kharif and rabi season of 2021-22. Groundnut seed was treated with three different seed treatment chemicals viz., imidacloprid 600 FS, thiamethoxam 30 FS and imidacloprid 200 SL at recommended dose and double dose and their persistence was studied. The residues of the test 3 insecticides were estimated at 0 days (treated seed) then 7, 14, 28, 35, 60 and 90 days after sowing and also in harvested pods. The initial deposit of residues in treated seed were 0.14 and 0.16 mg kg-1 incase of imidacloprid 600 FS at single and double dose, respectively and in imidacloprid 200 SL residue of 0.11 and 0.25 mg kg-1 and for thiamethoxam 30 FS residue of 0.20 and 0.35 mg kg-1 were observed. In 7days leaf samples the residue deposit of 0.06 and 0.21 mg kg-1 were observed in thiamethoxam 30 FS at single and double dose, respectively. In the leaf samples collected at 14, 28, 35, 60 and 90 DAS and also in harvested pods, no residues of insecticides were noticed. Four insecticides alone and in combination with two fungicides were applied to the groundnut seed and the subsequent effects were studied at Crop Physiology Laboratory, Tirupati. From this study, it was observed that treatments with thiamethoxam 30 FS + mancozeb 75% WP (T10), imidacloprid 200 SL + tebuconazole 2 % DS (T7), chlorpyriphos 20 EC + tebuconazole 2% DS (T8) recorded consistently effective on germination, seedling growth, seedling dry weight and seedling vigour index - I and II till 60 days. There was reduction in germination loss as well physiological quality over time. xv Field experiment was conducted to evaluate “the efficacy of seed treatment and sequential spray on sucking insect pests incidence in groundnut” at college farm, S.V. Agricultural College, Tirupati during kharif, 2021 in Randomized Block Design with 12 treatments and 3 replications. At the time sowing, groundnut seed was treated with imidacloprid 600 FS @ 2.0 mL kg-1 (+4 mL water) and thiamethoxam 30 FS @ 2.0 mL kg-1 (+4 mL water). Imidacloprid 600 FS @ 2mL kg-1 seed treatment was the most effective in controlling thrips and leaf hoppers damage by 68.5 and 48.0 per cent reduction over control upto 35 DAS. At 35 days after sowing, foliar spray were imposed to known their efficacy in groundnut against sucking pests. Among the different treatments, imidacloprid 600 FS seed treatment + imidacloprid 200 SL spray (T8) and imidacloprid 600 FS seed treatment + thiamethoxam 25 WDG spray (T6 ) spray were the effective treatments with 64.3 and 63.9 per cent reduction over control against thrips and for leaf hoppers, imidacloprid 600 FS seed treatment + thiamethoxam 25 WDG spray (T6) and imidacloprid 200 SL spray (T5) were the best treatments with 66.5 and 63.4 per cent reduction over control. The highest pod yield was obtained from plots treated with (T8) imidacloprid 600 FS seed treatment + imidacloprid 200 SL spray (26.10 q ha-1) followed by (T6) imidacloprid 600 FS seed treatment + thiamethoxam 25 WDG spray (25.26 q ha-1) and (T10) thiamethoxam 30 FS seed treatment + thiamethoxam 25 WDG spray (22.33 q ha-1) as compared to untreated control (16.93 q ha-1).EnglishThesis