Standardization of technique for evaluation of wheat (Triticum aestivum) genotypes against spot blotch caused by Cochliobolus sativus under field epiphytotics in eastern India

A study was conducted during 2001-2002 to 2003-2004 crop seasons to. develop an open field technique for the evaluation of wheat (Triticum aestivum L. emend. Fiori & Paol.) genotypes for resistance against spot blotch caused by Cochliobolus salivus (Ito & Kurib) Drechs. ex Dastur under artificial epiphytotics in the hot spot area of eastern India. Consecutive inoculations of susceptible wheat variety 'HP 1633' using aqueous spore suspension of Faizabad strain of the pathogen containing 8-10 conidiao/microsciopic field under 10 X in the open field with one light irrigation 3 days prior to and post-inoculation, at crop growth stages 47 and 57 resulted in severe epiphytoyic (score 89). This technique on 3 years testing gave reproducible results comparable with those obtained under controlled polyhouse technique. Three hundred ninety-four genotypes evaluated using this technique yielded two, namely 'IBWSN 8 V and 'SAWSN 12' resistant and 103 moderately resistant genotypes.