Variability, epidemiology and management of Tilletia indica Mitra, the incitant of Karnal bunt of wheat
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Date
2019-11
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Publisher
CCSHAU, Hisar
Abstract
Karnal bunt disease of wheat continues to be a potential threat to production and trade
of wheat. The present study was planned to study cultural, morphological, molecular and
pathogenic variability in Tilletia indica, epidemiology and management of this disease. On
the basis of cultural and morphological characteristic, the largest teliospore size was observed
in Bhiwani isolate, whereas Kapurthala isolate was having the smallest size. Different Karnal
bunt isolates colony colour were white, yellowish white, creamy, creamish yellow and
creamish white whereas, culture colony growth pattern of isolates were erect, compact,
clustering, crustose, appressed, spreading and leathery. Maximum teliospore germination,
primary sporidia formation and secondary sporidia production was recorded at 18°C in
Pantnagar isolate. Best teliospore germination occurred at pH 6.0 followed by pH 5.0
Maximum coefficient of infection was expressed in HD2967 followed by DPW 621-50.
Pantnagar isolate exhibited maximum mean coefficient of infection followed by Bhatinda and
the least was observed in Mahendergarh isolate. Pantnagar isolate was most virulent as well
as had maximum sporulation. Karnal bunt resistant reaction in three differentials namely HD
29, HD 30 and Aldan were noted. In molecular variability twelve molecular markers were
tested against 10 Karnal bunt isolates and characterized into 3 major groups. Karnal bunt
incidence had significant correlation with maximum temperature, rainy day and total rainfall
during earhead emerging stage Two hundred seventy nine genotypes showed less than 5
coefficient of infection against Karnal bunt thereby expressing resistant reaction and 221
genotypes were susceptible having more than 5 per cent coefficient of infection under
artificial inoculation condition. Maximum disease control was obtained by propiconazole
25% EC (0.1%) application, followed by combination of propiconazole 25% EC (0.05%),
neem seed kernel and Trichoderma harzianum.