Mishra, RanimaGogoi, Kulumanali2023-11-222023-11-222021https://krishikosh.egranth.ac.in/handle/1/5810201718The present investigation was conducted for identification, characterization and management of pumpkin mosaic disease in Assam. A roving survey was conducted during 2019-2021 in Jorhat, Golaghat, Karbi Anglong, Biswanath Chariali and Charaideo to determine the disease incidence through symptomatology, vector population count and detection of the viruses associated with mosaic disease of pumpkin through serodiagnostic (DAS-ELISA) and molecular assay (PCR and RT-PCR). Symptomatology revealed various degrees of mosaic, mottling, vein clearing, vein banding, chlorosis, leaf distortion, small, crinkled, deformed leaves and malformed fruits with mosaic and chlorotic spots resulting in reduced yield and production. Serological detection through DAS-ELISA confirmed the association of Cucumber mosaic virus (CMV) in CMV suspected pumpkin samples. The DAS-ELISA assay revealed disease incidence of 52.38 per cent in Golaghat district and 35.71 per cent in Jorhat district. Two different types of aphid vectors viz., Aphis gossypii and Myzus persicae were observed in all the surveyed locations. Total genomic RNA extracted from symptomatic and asymptomatic pumpkin plants were subjected to RT-PCR assays using CMV, zucchini yellow mosaic virus (ZYMV) and watermelon mosaic virus (WMV) specific primers and Deng universal primer for detection of begomovirus viz., pumpkin yellow vein mosaic virus (PYVMV). RT-PCR assay revealed the presence of CMV in the samples which yielded the desired amplicon size of 593 bp. No amplification was obtained from the samples for ZYMV and WMV. PCR product of CMV infected sample from Jorhat district viz., CMV-CP Jorhat isolate was sequenced and compared with the known CMV isolates worldwide using nucleotide BLAST programme at National Centre for Bio Informatics (NCBI) and Mega X software. The sequence similarity of CMV-CP Jorhat isolate ranged from 93.11 per cent to 99.16 per cent with worldwide CMV isolates. A field experiment was conducted for management of pumpkin mosaic disease through integrated approach. It was evident from the field experiment that there was low disease incidence with low vector population as well as high yield in the treatments of hot water seed treatment at 50⁰C for 10 minutes and spraying of neem formulation @3ml/lit at 15, 30, 45 and 60 days after transplanting (T1) followed by hot water seed treatment at 50⁰C for 10 minutes and spraying of Imidacloprid @2ml/lit at 15, 30, 45 and 60 days after transplanting (T6) than the other treatments with the highest yield (80.00 q/ha) recorded for the treatment T1 with highest per cent reduction of disease over control (53.22 per cent).EnglishThesis