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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 azedarachL. and Azadirachta indicaL. were assessed against the pathogen. Laboratory screening trials with cell-free culture filtrate showed the maximum reduction in growth of M. phaseolinawith T. harzianum,followed by T. viride. Various concentrations (1–5%) of methanolic leaf extract of A. indicashowed more reduction in fungal biomass than M. azedarach. Pot experiment was performed by T. harzianum, T. viride, and dry leaf biomass of A. indicaagainst M. phaseolina. Results revealed that potted soil amended with T. harzianumin combination with 1–3% dry leaf biomass of A. indicaheld a significant potential to decrease disease incidence to 20–25% and improve plant growth attributes up to fourfolds over positive control inoculated with M. phaseolinaonly. 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.

Background: Sclerotium rolfsiiis a soil-borne fungal pathogen causing diseases in more than 500 plant species. It causes southern blight disease in chili. Chemical fungicides are used to control this disease, which also pollute the environment. The present study was designed to assess the potential of two species of plant-growth-promoting rhizobacteria (PGPR) viz. Bacillus megateriumand Pseudomonas fluorescence, and an allelopathic weed, Anagallis arvensisL., for the control of southern blight disease of chili. Results: Initially, three PGPR strains, viz. B. megateriumOSR3, B. megateriumZMR6, and P. fluorescencePF-097, were selected for their in vitro antagonistic assessment against S. rolfsiiby dual culture technique on potato dextrose agar medium. OSR3 showed the highest antagonistic potential (68%), followed by PF-097 (54%) and ZMR6 (33%).In a pot experiment, the two best strains of PGPR, namely OSR3 and PF-097, and dried biomass of A. arvensis(DBA) in different concentrations (1, 2 and 3%) were used to manage southern blight disease of chili.In positive control treatment (S. rolfsiionly), plant survival was low (73%) than the negative control (100%). OSR3, PF-097, OSR3 + 2% DBA, and PF-097 + 2% DBA significantly enhanced plant survival over positive control. The highest increase in chili growth over positive control was recorded due to OSR3, followed by PF-097 inoculations. Contents of carotenoid and chlorophyll were significantly decreased due to the fungal pathogen and improved due to PGPR strains. Application of the two PGPR strains and different concentrations of A. arvensisdistinctly increased the catalase (CAT), peroxidase (POX), and polyphenol peroxidase (PPO) activities over positive control. Conclusions: The present study concluded that PGPR strains B. megateriumOSR3 and P. fluorescencePF-097 can control southern blight disease effectively and increase growth and yield of chili.

Sclerotium rolfsiiis a soil-borne plant pathogen that causes root diseases in hundreds of plant species. It also causes collar rot disease in chickpea (Cicer arietinumL.). The present pot study was carried out to investigate the effect of soil amendment with dry biomass of a weed Chenopodium albumL. and two antagonistic fungi, namely Trichoderma harzianumand T. viride, on growth and yield of chickpea variety Noor 2009 in soil infected with S. rolfsii.The pathogen-contaminated soil was amended either with 1, 2, or 3% C. albumdry biomass, T. harzianum, and T. viridealone, or combinations of either of the two Trichodermaspecies and plant dry biomass. The lowest shoot and root dry biomass and grain yield of chickpea were recorded in S. rolfsiiinoculation alone without any soil amendment (positive control). Plant growth and yield were significantly and gradually increased over positive control with an increase in C. albumdry biomass application in the soil. Likewise, soil application of either of the two Trichodermaspecies significantly enhanced plant growth and yield over positive control under biotic stress of S. rolfsii.Combined application of either T. harzianumor T. viridewith 3% dry biomass of C. albumalso proved highly effective in alleviating biotic stress of S. rolfsiion growth and yield of chickpea.