Studies on White Rust Disease of Indian Mustard caused by Albugo candida Kuntze
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Date
2022
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Publisher
DRPCAU, PUSA
Abstract
Oilseed brassica, often known as rapeseed mustard, is the second-most
significant oilseed crop in the world after soyabean. With a productivity of 1187
kg/ha, Bihar produces 0.10 mt from an area of 0.08 mha. Because of its crucial human
nutrition, an essential component for animal feed, and high yield efficiency, mustard
is commonly referred to as the "queen of oilseeds." White rust is one of the most
damaging disease, and it severely hinders the production of oilseed Brassicas. The
fungus not only lowers production by causing crop foliar damage, but it also
drastically reduces both seed (siliqua) as well as oil yield by harming siliqua during
the pod-formation stage. Depending on the severity of both foliar and staghead phase
of the disease, the per cent yield losses ranging from 23.0-89.8% in Indian mustard
(B. juncea L.) in India (Lakra and Saharan, 1989).
White pustules, or sori, appear in a range of sizes and shapes on leaves, stems,
inflorescences, and pods. Sori start out as distinct regions but eventually blend to
cover whole plant organs. The affected host tissue frequently swells and distorts
forming staghead with downy mildew disease.
Survey was conducted during Rabi 2021-22 in the adjacent districts of Pusa,
they are Samastipur, Muzaffarpur, Vaishali and Darbhanga. During survey it was
found that infection prevailed in all the areas surveyed and incidence of the disease
ranged in between 15.50- 20.34 per cent in which the highest incidence (20.34%) was
recorded from Muzaffarpur district and lowest incidence (15.50%) was recorded from
the Vaishali district.
In the current study, 52 Brassica genotypes/entries were evaluated to find out
the resistance reaction against the white rust disease. According to the disease severity
scale (0-9), 24 entries was found to be immune to disease, followed by 7 as highly
resistant, 3 resistant and 16 as moderately resistant and 2 entries were found to be
susceptible.
It was found that the typical white rust pustules appeared late on the mustard
leaves of early sown crop while the disease appeared early on late sown crop. With
the postponement in sowing, white rust incidence and severity increased. Weather
factors like rainfall, temperature, and atmospheric humidity had a big impact on how
the mustard develop white rust disease. Maximum temperature and relative
humidity were found to be negatively correlated with the per cent disease severity.
While positive correlations were reported between Minimum temperature and per
cent disease severity. Light rainfall increases the disease while heavy rainfall causes
reduction in the disease.
Foliar spray of fungicides were found to be very effective against white rust
disease. Among different fungicides, Metalaxyl 4% + Mancozeb 64%WP @ 0.25 was
found to be most effective for reducing the disease with minimum per cent disease
severity of 18.86% and causes 36.10% increase in yield. While Mancozeb 75WP @
0.25% was found to be least effective for reducing the white rust disease. The highest
incremental cost benefit ratio (1:7.46) was reported in treatment with single spray of
Propiconazole 25 EC @ 0.1%.