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Variability of Colletotrichum truncatum through morphological & molecular approaches and management of pod blight complex of soybean in India

Shamarao Jahagirdar: University of Agricultural Sciences,Dharwad

<div>The association of <em>Colletotrichum truncatum, Alternaria alternata, Macrophomina phaseolina</em> have been observed in causing anthracnose/pod blight of soybean in northern Karnataka. However, <em>Colletotrichum truncatum</em> has been found predominantly associated in causing anthracnose disease. Variability study indicated that, there was much difference in colony colour ranging from cottony white to dark grey, the spore shape was only truncate type and there is no difference with respect to spore size of <em>Colletotrichum truncatum</em> isolates. The results obtained from the cluster analysis revealed that sub cluster groups composed of isolates belonging to same geographical locations with distinct variability. Out of 19 genotypes, the genotypes <em>viz., </em>DSb 12, DSb 20, DSb 23-5 and Kalitur were found highly resistant with a disease grade of one. The genotype JS 335 was highly susceptible to anthracnose with a maximum disease grade of nine. The two year investigation (2014 &2015) revealed that the integrated management by seed treatment with Thiram+Carboxin @ 2g/kg of seed followed by spray at 55 and 75 DAS with Trifloxystrobin + Tebuconazole @ 0.1% was found effective in reducing anthracnose severity and enhancing the yield both at Dharwad and Ugarkhurd. In modular approach study conducted over three years(2013-2015), the chemical module/adapative module have been recommended for the management of major diseases(rust, anthracnose and purple seed stain) and insect pests(defoliaters and Pod borer) in a holistic approach.</div>