Anti-mycotic potential of Trichoderma spp. and leaf biomass of Azadirachta indica against the charcoal rot pathogen, Macrophomina phaseolina (Tassi) Goid in cowpea

Macrophomina phaseolina (Tassi) Goid is a destructive pathogen of cowpea that causes serious charcoal rot disease with significant yield losses. Antifungal activity of three indigenous Ascomycetes viz., Trichoderma harzianum, T. viride, and T. hamatum, and two Meliaceae members, i.e., Melia azedarach L. and Azadirachta indica L. were assessed against the pathogen. Laboratory screening trials with cell-free culture filtrate showed the maximum reduction in growth of M. phaseolina with T. harzianum, followed by T. viride. Various concentrations (1–5%) of methanolic leaf extract of A. indica showed more reduction in fungal biomass than M. azedarach. Pot experiment was performed by T. harzianum, T. viride, and dry leaf biomass of A. indica against M. phaseolina. Results revealed that potted soil amended with T. harzianum in combination with 1–3% dry leaf biomass of A. indica held a significant potential to decrease disease incidence to 20–25% and improve plant growth attributes up to fourfolds over positive control inoculated with M. phaseolina only. Physiology of the host plant was altered due to the incorporation of various soil amendments resulting in reduced activities of antioxidant enzymes (catalase, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase). It was concluded that fungal antagonists and allelopathic chemicals would be an effective and eco-friendly means of managing the charcoal rot disease.