Surjeet SinghMan Mohan2016-11-252016-11-252016http://krishikosh.egranth.ac.in/handle/1/87471Wet bubble disease caused by Mycogone perniciosa is one of the most devastating fungal disease and causes considerable yield loses in Agaricus bisporus. The present investigation on symptomatology, morphology, physiology, chemosensitivity and genetic variability was carried out under in vitro with fifteen isolates of M. perniciosa collected from major mushroom growing areas. The symptoms induced by different isolates of M. perniciosa varied from thick stipe to sclerodermoid having brown amber coloured droplets to internal browning. These were categorized on the basis of brown amber colour droplets, gills infection and foul smell occurrence. Isolates viz., LDP, RSN and BSN1 showed the symptoms on pileus like dark brown to light brown colour, while some isolates exhibited the brown amber droplets. A wide variation in symptoms was also detected when isolates were compared with isolates from widely reported origin of geographical regions in Haryana, Punjab and Himachal Pradesh. Isolate TPN showed thick stipe, slow mycelial growth with slightly feathery, dense mycelium and lemon colony colour. While symptoms variation observed among the isolates of M. perniciosa were compared with morphological, physiological and genetic variability, it was observed that the isolates, KSN and BSN2 produced fluffy, even, very feathery and brown in colony colour was recorded fastest growing. In results 25oC was found most suitable temperature for mycelial growth of Mycogone perniciosa. While, the pH level 7.0 was found optimum for mycelial growth of the isolates studied. These two isolates viz., KSN and BSN2 were highly diversed from rest of isolates of the M. perniciosa showing wide genetic distance. On the bsasis of chemosensitivity to metalaxyl MZ among these fifteen isolates, eleven isolates of pathogen were highely sensitive but none of isolate were under less sensitive group to Mycogone perniciosa isolates. Interaction studies between Mycogone perniciosa isolates and Agaricus bisporus strains showed mycelial inhibition. The highest pair wise genetic similarity i.e., 92.0 per cent was observed between sub cluster isolates RSN and BSN1 followed by 85.0 per cent genetic similarity between isolates KSN and BSN2 of major cluster B. In future it is likely these two isolates of Mycogone perniciosa can be used in the screening programme of strains of Agaricus bisporus.enThesis