Patil, M SDevaraju2019-08-222019-08-222000No. of references 147http://krishikosh.egranth.ac.in/handle/1/5810123065"Potato is one of the most important commecial vegitable crops cultivated in Kamataka Among the viral diseases mosaics and leaf roll are most common. The survey was conducted during kharif 1999 and summer 2000, the incidence of viral diseases was ranged from 4.20 to 66.75 per cent. Incidence of severe mosaic ranged from trace to 36.00 per cent and leaf roll incidence ranged from 4.20 to 40.75 per cent in both Hassan and Kolar districts, whereas mild mosaic incidence was not noticed in both the districts The. mild mosaic virus (PVX) was sap transmissible to different indicator plants and produced systemic symptoms on tobacco, Micotiana glutinosa, tomato and Capsicum annuum and local lesions on cowpea, beans, Gomphrena glohosa and Chenopodtum amaranticolor. Severe mosaic virus (PVY) produced systemic symptoms on tobacco, Nicotiana tabacum var. white burley and samsun, Nicotiana glutinosa, Datura metel, Nicandra physaloids. Petunia hyhrida and Capsicum annuum and local lesions on Chenopodium amaranticolor. The mild mosaic, severe mosaic and leaf roll viruses were transmitted through seed tubers. Aphids {Myzus persicae) transmitted severe mosaic and leaf roll viruses in a non-persistent and persistent manner, respectively. The mosaics had slight effect on yield and yield parameters, whereas the leaf roll infection at early stages resulted in greater yield loss than later stages infection. The lower disease incidence and the higher tuber yield was obtained in early planted crop (June 1st to June 21st) than late planted crop, therefore the spread of diseases could be minimised by adopting early planting Mulching with polyethylene sheet and aluminium foil immediately after emergence resulted in reduction of severe mosaic and leaf roll diseases incidence. In tissue culture studies, maximum number of PVY free potato plantlets were obtained by meristem-tips obtained from seedlings of true potato seeds (94.44) than that of severe mosaic (PVY) infected plants (69.44%)."ennullThesis