Biocontrol potential of Trichoderma erinaceum It-58 and T. afroharzianum P-8 against Neoscytalidium dimidiatum, pathogen responsible of root rot in cucumber (Cucumis sativus)

Green agricultural development requires safe, effective, and environmentally friendly plant disease control measures. This study evaluated the antagonistic properties of Trichoderma erinaceum It-58 and Trichoderma afroharzianum P-8 against Neoscytalidium dimidiatum , as well as their ability to promote growth and induce biochemical resistance in cucumber seedlings. The pathogen responsible for both cucumber fruit rot and seeds damping off was isolated and identified morphologically. The antagonistic potential of the Trichoderma strains was assessed using dual culture, volatile, and non-volatile organic compound methods. For pot experiments, seeds coated with antagonists were pre-germinated and transplanted. Twenty-one days later, roots were infected with the pathogen. Fifteen days post-infection, seedlings were harvested to evaluate growth parameters (height, biomass, diameter) and biochemical parameters (polyphenols, proteins, peroxidases, polyphenol oxidases). The pathogen was identified as Neoscytalidium dimidiatum . In dual culture, T. erinaceum and T. afroharzanium inhibited the pathogen by 74.36% and 68.20% respectively. Diffusible non-volatile substances showed even greater inhibition of mycelial growth at 71% ( T. erinaceum ) and 97% ( T. afroharzanium ). No inhibition was observed with volatile organic compounds. In pot experiments, both antagonists significantly stimulated plant growth parameters and reduced disease incidence (16.67% for T. afroharzianum , 33.33% for T. erinaceum ). They induced a significant increase in polyphenol content while significantly decreasing peroxidase and polyphenol oxidase activities in treated and infected plants compared to controls. There was a significant positive correlation between disease incidence, polyphenol content, and peroxidase activity, and a negative correlation with polyphenol oxidase. Thus, T. erinaceum and T. afroharzanium can effectively promote cucumber growth and prevent seedling wilt caused by N. dimidiatum .