Author(s):

C Yamuna, P Kishore Varma and RD Prasad

Abstract: Castor graymold caused by Botryotinia ricini is one of the most destructive diseases of castor causing heavy yield losses. Ecologically sustainable approaches towards tackling diseases are gaining importance owing to ill-effects of chemical pesticides. One among them is biological control through application of fungal and bacterial antagonists that has wide range applicability against plant diseases. Biological control using antagonistic microorganisms is a potential eco-friendly and sustainable approach, and the effective bioagents can be applied for the efficient management of castor gray mold to ensure better returns. Keeping in view the importance of disease in castor production, the present investigation was carried out to identify the Trichoderma species against B. ricini under in vitro and glasshouse conditions. The antagonistic activity of twelve Trichoderma isolates was evaluated against Amphobotrys ricini under laboratory and greenhouse conditions. Among the Trichoderma isolates tested, Trichoderma asperellum isolate 1, T. harzianum isolate 5 and T. asperellum isolate 3 recorded significantly highest percent inhibition of mycelial growth of A. ricini. These Trichoderma isolates were found to have high chitinase and glucanase activity compared to other isolates tested. Further, greenhouse experiments have revealed the efficacy of T. harzianum isolate 1, T. asperellum 2, T. harzianum isolate 4 and T. harzianum isolate 3 in reducing graymold severity. The antagonistic isolates were found to have high chitinase and glucanase activity.

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