Bioagent based integrated management of Phytophthora blight of pigeonpea

Abstract

Phytophthora blight (Phytophthora drechsleri f. sp. cajani) is one of the major yield limiting factors of short duration varieties of pigeonpea (Cajanus cajan). For eco-friendly and sustainable management of the disease, four antagonists, Pseudomonas fluorescens, Bacillus subtilis, Trichoderma viride and T. hamatum, were evaluated under in vitro and in vivo conditions. P. fluorescens produced maximum inhibition zone, while Trichoderma species overgrew on the host mycelium and caused lysis. The fungicides apron (metalaxyl), ridomil MZ (metalaxyl + mancozeb), capton (captaf), difolatan (captafol), thiram (tetramethylthiuram disulphide) and bavistin (carbendazim) at both 0.3 and 0.6% were found to be compatible with P. fluorescens while B. subtilis was compatible only with apron at 0.3%. T. viride grew and sporulated well at 0.3 and 0.6% apron and 0.2% ridomil MZ. The bioagents proved to have potential and those which were compatible under in vitro were evaluated under field conditions. The efficacy of fungicide in combination with bioagents was greater compared to fungicide alone. The integration of P. fluorescens with apron or ridomil MZ as seed treatment significantly reduced the Phytophthora blight incidence and enhanced seed germination and grain yield.