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Sclerotium rolfsii is a soil-borne plant pathogen that causes root diseases in hundreds of plant species. It also causes collar rot disease in chickpea (Cicer arietinum L.). The present pot study was carried out to investigate the effect of soil amendment with dry biomass of a weed Chenopodium album L. and two antagonistic fungi, namely Trichoderma harzianum and 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. album dry biomass, T. harzianum, and T. viride alone, or combinations of either of the two Trichoderma species and plant dry biomass. The lowest shoot and root dry biomass and grain yield of chickpea were recorded in S. rolfsii inoculation alone without any soil amendment (positive control). Plant growth and yield were significantly and gradually increased over positive control with an increase in C. album dry biomass application in the soil. Likewise, soil application of either of the two Trichoderma species significantly enhanced plant growth and yield over positive control under biotic stress of S. rolfsii. Combined application of either T. harzianum or T. viride with 3% dry biomass of C. album also proved highly effective in alleviating biotic stress of S. rolfsii on growth and yield of chickpea.

Background Sclerotium rolfsii is 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 megaterium and Pseudomonas fluorescence, and an allelopathic weed, Anagallis arvensis L., for the control of southern blight disease of chili. Results Initially, three PGPR strains, viz. B. megaterium OSR3, B. megaterium ZMR6, and P. fluorescence PF-097, were selected for their in vitro antagonistic assessment against S. rolfsii by 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. rolfsii only), 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. arvensis distinctly increased the catalase (CAT), peroxidase (POX), and polyphenol peroxidase (PPO) activities over positive control. Conclusions The present study concluded that PGPR strains B. megaterium OSR3 and P. fluorescence PF-097 can control southern blight disease effectively and increase growth and yield of chili.

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Antifungal activity of Monothecabuxifolia methanolic extract and its various fractions were assessed against Macrophominaphaseolina, a soil-borne fungal pathogen of more than 500 vegetal species as well as rare and emerging opportunistic human pathogen. Different concentrations of methanolic extract (3.125 to 200 mg mL−1) inhibited fungal biomass by 39–45%. Isolated n-hexane, chloroform and ethyl acetate fractions suppressed fungal biomass by 32–52%, 29–50% and 29–35%, respectively. Triterpenes lupeol and lupeol acetate (1, 2) were isolated from n-hexane while betulin, β-sitosterol, β-amyrin, oleanolic acid (3–6) were isolated from chloroform fraction. Vanillic acid, protocatechuic acid, kaempferol and quercetin (7–10) were isolated from the ethyl acetate fraction and identified using various spectroscopic techniques namely mass spectroscopy and NMR. Antifungal activity of different concentrations (0.0312 to 2 mg mL−1) of the isolated compounds was evaluated and compared with the activity of a broad spectrum fungicide mancozeb. Different concentrations of mencozeb reduced fungal biomass by 83–85%. Among the isolated compounds lupeol acetate (2) was found the highest antifungal against M.phaseolina followed by betulin (3), vanillic acid (7), protocatechuic acid (8), β-amyrin (5) and oleanolic acid (6) resulting in 79–81%, 77–79%, 74–79%, 67–72%, 68–71% and 68–71%, respectively. Rest of the compounds also showed considerable antifungal activity and reduced M.phaseolina biomass by 41–64%.

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Macrophomina phaseolina is a highly destructive pathogen of more than 500 plant species. It is difficult to eradicate it through chemical means as no patented fungicide is available against this pathogen. Biological control is the possible alternative method for its suitable management. The present study was carried out to evaluate the biocontrol potential of five Trichoderma spp. against M. phaseolina and the possible mechanisms of action. Identifications of all the Trichoderma spp. viz. T. hamatum, T. harzianum, T. koningii, T. longipile and T. viride were confirmed on molecular basis by using two universal primer pairs namely ITS and EF1. Their biocontrol potential was evaluated in dual culture plate method where T. viride showed the highest inhibitory efficacy (63%) against M. phaseolina. T. koningii, T. hamatum and T. longipile showed akin effects by arresting growth of the pathogen by 46–47% followed by T. harzianum (28%). To find out the mechanisms of action, secondary extrolites of the best biocontrol fungus T. viride were tested against the pathogenic genomic DNA where all the concentrations partially degraded DNA bands after 24 h of incubation and a complete DNA band disappearance was noted after 48 h incubation. In addition, T. viride culture filtrates were partitioned with chloroform and ethyl acetate and subjected to GC-MS analysis for identification of potential antifungal constituents. The most abundant identified volatile compounds in the two organic solvent fractions were 9,12-octadecadienoic acid (Z,Z)- (44.54%), n-hexadecanoic acid (24.02%), hexadecanoic acid, 2-hydroxy-1-(hydroxymethyl) ethyl ester (14.25%), 9-tricosene, (Z)- (10.43%) and [1,1'-bicyclopropyl]-2-octanoic acid, 2'-hexyl-, methyl ester (10.43%). To conclude, T. viride was the best biocontrol agent against M. phaseolina and acts against the pathogen by DNA disintegration and production of antifungal secondary metabolites. © 2021 Friends Science Publishers