ABSTRACT White rust/white blister disease of rapeseed‐mustard caused by Albugo candida is one of the significant diseases, which adversely affect the production and productivity of the crop. For managing the disease in a very effective way, host plant resistance can be considered as the most suitable, cost effective and ecofriendly method. The host resistance may breakdown due to emergence of new pathotypes/races, therefore there is an emergent need to identify host differentials for the differentiation of A. candida isolates occurring at different geographical mustard growing region in India. Further there is also a need to identify highly virulent and highly aggressive isolates so that could be exploited during screening of resistance sources against white rust pathogen in Brassica breeding materials to get wide source of resistance. Keeping above in view the present investigation was taken, in which 44 diverse A. candida isolates belonging to 06 different Brassica spp. collected from 17 states of India were cross inoculated on 32 different Brassica genotypes/cultivars. Based on disease reactions on the host, 24 groups of differential hosts were identified and 44 A. candida isolates were also classified in 12 Groups based on the infectivity on 32 Brassica genotypes/cultivars. Further, on the basis of virulence, 44 A. candida isolates were categorised as highly virulent (09), virulent (12), moderately virulent (16) and least virulent (07) and on the basis of and aggressiveness isolates were categorised as highly aggressive (08), aggressive (06), moderately aggressive (14) and least aggressive (16). These highly virulent and highly aggressive A. candida isolates could be exploited for the screening of resistance sources against white rust disease in Brassica breeding materials.
Tewari et al. (Sun,) studied this question.