Studies on Integrated Management of Powdery Mildew of Blackgram Caused by Erysiphe polygoni DC
Loading...
Date
2013
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
UAS, Dharwad
Abstract
Powdery mildew caused by Erysiphe polygoni DC is one of the major constraints in
the production of black gram. Incidence of black gram powdery mildew was maximum in
Belgaum district (68.72%) and minimum in Gadag district (20.23%) during study period. The
rDNA-ITS sequencing of E. polygoni indicated that Dharwad isolate is having more than 90
per cent homology with reported E.polygoni isolates in NCBI genebank.
The per cent reduction of chlorophyll was more in susceptible variety than in resistant
cultivar. Higher amount of total sugar, reducing sugar and non-reducing sugar were recorded
in susceptible variety compared to resistant cultivar. Non-reducing and total sugar were
synthesized at faster rate in susceptible cultivar than in resistant cultivar. Healthy leaves of
resistant cultivar had 8.34 mg/g total phenols and it was increased to 16.78 mg/g after
infection. Accumulation of total phenols was at faster rate in resistant cultivar (101.19%)
compared to susceptible cultivar (33.85%).
LBG-17 showed resistant reaction and four genotypes had highly susceptible reaction
against powdery mildew under glasshouse condition. Among the 126 genotypes screened
under natural condition only three genotypes were resistant, 14 moderately resistant and
others had susceptible reaction.
Among various fungicides tested in vitro azoxystrobin 250% SC @ 0.1 % was most
effective in inhibiting conidial germination. Whereas, azadirachtin @ 5% and Bacillus
subtilis @ 6g/L were found most effective among botanicals and bioagents respectively. In
field evaluation azoxystrobin 250% SC @ 0.1% (916 kg/ha), azadirachtin 1500 ppm (1:10)
@ 5% (591 kg/ha) and B. subtilis @ 6g/L (590 kg/ha) were superior with least PDI and
higher seed yield.
Host range studies indicated the ability of the E. polygoni to survive on Euphorbia
geniculate (Pill pod spurge garden) and serve as collateral host.