Differential response of Indian mustard (Brassica juncea) genotypes to white rust disease-causing fungi Albugo candida over a two-year interval under controlled epiphytotic conditions

Abstract

White rust in oilseed Brassicas is caused by obligate oomycete pathogen Albugo candida and is considered an important 
disease in Indian mustard (Brassica juncea) reducing seed yield significantly. In the present study, twenty-five 
genotypes of B. juncea were screened at the cotyledonary stage against Wellington isolate of A. candida (Ac-Wltn) for 
two years (2016–18) at ICAR–Indian Agricultural Research Institute (IARI), New Delhi and one year (2021–22) at 
IARI–Regional Station, Wellington under controlled conditions. Ten genotypes (Donskaja, Heera, MSTWR-17-13, 
MSTWR-17-15, PDZ-1, PDZ-3, PDZ-4, PDZ-5, PM-24, and Pusa Karishma) of B. juncea were found highly resistant at 
ICAR–IARI, New Delhi during 2016–18. However, all the genotypes including resistant ones were found to be 
susceptible with different levels of susceptibility under controlled conditions at IARI–Regional Station, Wellington 
during 2021–22. It might be due to the prevalence of more than one isolate in the Nilgiris hills or the breakdown of 
resistance in the resistant genotypes against Ac-Wltn.