Assessment of yield losses in Brassica juncea due to downy mildew (Hyaloperonospora brassicae)

Abstract

Susceptibility of cultivated varieties of Indian mustard (Brassica juncea L.) to downy mildew (DM),
[Hyaloperonospora brassicae (Gaum.) Gçker; formerly Peronospora parasitica] is one of the major
constraints in increasing crop productivity. This study reports the effect of DM on yield of three important
Indian mustard cultivars as affected by several yield parameters. Compared to the healthy plants,
DM-infected plants reduced yield by 42.6, 46.8 and 66.7 percent in cvs. Rohini, Varuna and NRCDR-2,
respectively. DM infection significantly reduced average plant height, 1000-seed weight and oil content of
seeds. Number of primary branches per plant however, was significantly higher in infected than in healthy
plants. Generally, the number of siliquae on main shoot, as well as, on primary branches was also significantly
lower in infected than in healthy plants. Quantification of economic impact showed that the yearly expected
loss in India due to DM was about 683.1 million Indian rupees, depending upon the disease severity.