Studies on Stem and Root Rot [Macrophomina phaseolina (Tassi) Goid.] of Sesame (Sesamum indicum L.) and it’s Management

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Agriculture University, Jodhpur
Sesame (Sesamum indicum L.) is oldest oil seed crop and affected by several diseases, in which Mcrophomina phaseolina causes heavy yield losses during cropping season. It caused stem and root rot and affect plant parts during all stages of the crop growth. Pathogen having a wide host range, survive in soil as saprophytic and in form of sclerotia, and management is difficult in nature, therefore it is a major problem in sesame growing areas. The disease incidence was (15.18 - 32.74%) recorded during survey in major sesame growing areas of Western Rajasthan. The disease samples were brought to laboratory for further studies. Disease incidence was found maximum in Pali district (32.74%) followed by Jodhpur (28.39%), Nagaur (27.79%) and lowest incidence was observed in Barmer district (15.18%). Mean disease incidence was 26.00%. Pathogen was isolated from infected stem and root parts and purified by using hyphal tip cut method. Proved pathogenicity through Koch’s postulates by using seed cum soil inoculation techniques and 55.32% disease incidence was observed. Five isolates were achieved namely, AUMP-1, AUMP-2, AUMP-3, AUMP-4 and AUMP-5 identified. The variability among the different isolates of M. phaseolina was studied to determine the growth parameter and sclerotial formation of each isolate. AUMP-1 was most virulent isolate. M. phaseolina grew best at 30ºC temperature and observed maximum mycelial growth (90.00 mm) in the isolate AUMP-1under in vitro conditions. In the cultural and morphological studies, M. phaseolina was initially appeared as dirty white mycelium then turn to fluffy white to black with minute dark black sclerotia on PDA medium. The hyphal branch was at dense and feathery angles with constriction of hyphal branches at their point of origin with closed septum. The microsclerotia were dark black in colour and varied in size with 70.27 – 99.00 µm. The pycnidia was not observed on cultural media. From the study on effect of solid cultural media, the highest radial growth and excellent sclerotial formation was obtained on PDA (90.00 mm) and proved best followed by Richard’s Agar (83.63 mm) for growth of M. phaseolina
Bairwa Pradip Kumar 2021. Studies on Stem and Root Rot [Macrophomina phaseolina (Tassi) Goid.] of Sesame (Sesamum indicum L.) and it’s Management. M.Sc. thesis, College of Agriculture, Agriculture University, Jodhpur.