P. S., SandhuYash Pal2017-06-202017-06-202011http://krishikosh.egranth.ac.in/handle/1/5810022039ABSTRACT White rust caused by Albugo candida (Pers.) Kuntze is a serious threat to the production of oilseed Brassica crops in India and around the world. Variation occurs w.r.t. infection of the pathogen on different species of oilseed Brassicas which encouraged us to carry out the studies on “Variability in A. candida (Pers.) Kuntze causing white rust of rapeseed-mustard”. Survey was conducted in different locations (Bathinda, Mansa, Barnala, Faridkot, Muktsar, Sangrur, Ferozepur, and Ludhiana) of Punjab to estimate disease incidence and severity of the disease. The disease incidence and severity of white rust ranged from 44.39-59.36 and 21.92-27.83 per cent, respectively, in different locations of Punjab. A total of 52 isolates were collected from different locations and varieties. These isolates were classified into three groups (AC-I, AC-II and AC-III) on the basis of pustule size, pustule shape and germination of sporangia. Three representative isolates of each group were tested on twelve differential host cultivars (B. juncea, B. nigra, B. napus, B. carinata, B. oleracea, B. tournifortii, B. rapa var. Toria, B. rapa (Brown sarson), B. rapa (Yellow sarson), Raphanus sativus, Sinapis alba and Eruca sativa) of rapeseed and mustard. AC-III group has most virulent and AC-II group showed least virulence based on disease reaction, incubation period, latent period, pustule size, shape, number of pustules per leaf and number of sporangia per pustule. Further, within AC-III group, Ac6 isolate was observed as more virulent than other isolates of same group. Hence, it is concluded that morphological and pathological variation exists in A. candida population from Punjab.ennullThesis