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Subject: Plant Pathology × Author: Parvesh Kumar × End date: 2023 × Start date: 2022 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Studies on morpho-molecular characterization, epidemiology and management of Rhizoctonia solani f. sp. sasakii Exner causing banded leaf and sheath blight of maize
    (CCSHAU, Hisar, 2023-03-09) Parvesh Kumar; Mehra, Rakesh
    Banded leaf and sheath blight (BLSB) caused by Rhizoctonia solani f. sp. sasakii has emerged as an economically important disease in most of maize growing areas of India, leading to considerable qualitative and quantitative losses in maize. The present investigation on survey and surveillance of banded leaf and sheath blight, epidemiology, management and morpho-metric, pathogenic, molecular characterization were carried out with fifty one R. solani isolates collected from different geographical locations of India. Occurrence of banded leaf and sheath disease intensity ranges from 4.47-55.62 per cent in major maize growing districts of Haryana during kharif 2020 and 2021. Maximum disease severity (55.62%) was in Panchkula, followed by Karnal (41.84%), Sonipat (39.96%), Ambala (32.66%), Kurukshetra (23.20%) and Yamunanagar (21.89%). Significant variations was observed among fifty one R. solani isolates on the basis of cultural and morphological characters and hierarchical cluster analysis differentiated all R. solani isolates into five major cluster (C1- C5). Molecular analysis confirmed that all the isolates belonged to R. solani species exhibited relation with anastomosis subgroup AG1-IA belong to maize crop causing BLSB disease and also in maize cultivated lands. In the pathogenic variations, isolates RS 29 from New Delhi and RS 1 from Karnal were found highly virulent. Out of four dates of sowing of maize, the highest disease intensity, AUDPC and AIR was observed in 1st date of sowing (16 June) followed by 2nd date of sowing (30 June), 3rd date of sowing (14 July) and least in 4th date of sowing (28 July) in all the seven maize hybrids. Maximum temperature range of (31.39-33.23°C), minimum temperature (25.36-26.73°C) with morning relative humidity (93.43-96.79%) and evening relative humidity (71.17-87.37%), rainfall (1.98-10.21 mm) and sunshine (4.90-7.47 h/day) were most congenial for disease development. Temporal progression was maximum in 34th to 35th and 37th to 38th meteorological weeks in seven maize hybrids. Temperature and relative humidity are the major components responsible for disease development and progression. Regression equation on relationship between disease development and weather parameters have been developed for seven maize hybrids. R2 value of regression equation in relation to weather parameters could comprise of disease level up to 96 to 98 per cent. Among seven maize hybrids, maximum AUDPC was recorded in QPM 9 and minimum in HQPM 4 in all the four dates of sowing. However, mean AUDPC of four dates of sowing were more in kharif 2021 as compare to kharif 2020 in maize hybrids QPM9, HQPM 4, HQPM 1 and HSC I. Mean AIR of four dates of sowing was highest in QPM 9 and minimum in HQPM 4 during both the years. Out of five hundred and seventy two maize genotypes (hybrids/inbred) screened against BLSB under artificial inoculated conditions, sixteen maize genotypes were resistant. Among sixteen plant extracts garlic, eucalyptus and pudina were most effective at 20 % concentration both in vitro and in vivo conditions. Under in vitro conditions bio agent Trichoderma sp. 1 was highly effective with 73.06 per cent mycelium growth inhibition followed by Trichoderma sp. 2 (59.72%) while, in vivo conditions T. viride was most effective and gave 33.32 per cent disease control followed by T. harzianum (27.86%). The fungicides fluxapyroxad 167 g/L + epoxiconazole 333 g/L SC, pyraclostrobin 13.3% + epoxiconazole 5% SE and propiconazole 25% EC were most effective both in vitro and in vivo conditions. In integrated management, out of eleven treatments, application of soil amendment of Trichoderma formulation @ 6T/acre FYM+ seed priming with salicylic acid @100 μg ml-1 + foliar sprays of azoxystrobin 2%+ difenoconazole 11.4% @ 0.1% and neem extract @1% was most effective against BLSB of maize.