EPIDEMIOLOGY AND MANAGEMENT OFANGULAR LEAF SPOT OF FRENCH BEAN CAUSED BY Phaeoisariopsis griseola (Sacc.) FERRARIS
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Date
2012
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Abstract
Abstract
Angular leaf spot caused by Phaeoisariopsis griseola (Sacc.) Ferraris is one of the most
important foliar disease of French bean in mid hills of Himachal Pradesh. Survey and surveillance
studies conducted in the present investigation revealed that the disease occurred in moderate to serve
form in different French bean growing localities of Solan, Shimla and Sirmour districts of Himachal
Pradesh. Temperature of 25°C was found optimum for conidial germination and the relative
humidity 95 percent with 24 h of leaf wetness period favoured the disease development under
controlled conditions. The epidemiological studies conducted under field conditions revealed that
moderate temperature (23 ± 2°C) and high humidity (>90%) prevailing during the rainy season found
to be congenial for the rapid disease progression. The in vitro evaluation of fungicides indicated
Sectin (fenamidone 10% + mancozeb 50% WG) and Index (mycobutanil 10% WP) as potent growth
inhibitor of P. griseola while amongst the botanicals, garlic and neem extracts were most promising.
Amongst the different fungal antagonist evaluated in in vitro studies Trichoderma harzianum proved
most inhibitory to P. griseola while testing their antagonistic efficacy through dual culture or through
its toxic substances. The integrated management studies conducted under field conditions revealed
that treatment consisting of seed treatment with Trichoderma harzianum @ 0.5% and Sectin @ 0.3%
followed by pre-sowing soil application of T. harzianum @ 2.5 kg/50 kg FYM/ ha and four periodic
sprays of Sectin @ 0.2% at 15 days interval started with the appearance of disease proved most
efficacious in limiting the angular leaf spot disease and enhancing the green pod yield.