Biological control effect of Trichoderma harzianum (Hypocreales: Hypocreaceae) against phytopathogens

Chemical pesticides are synthetic substances created to manage plant pests. Frequent chemical usage causes extensive damage to crops and contributes to pest resistance, leading to environmental contamination, harm to non-target organisms, the emergence of pesticide-resistant species, and potential health hazards for humans. The aim of this study is to isolate, identify, and characterize biocontrol agents Trichoderma harzianum and evaluate their effects on various plant phytopathogens. T. harzianum biocontrol effects were tested against various fungal phytopathogens, including Sclerotium rolfsii, Alternaria sp., Pythium aphanidermatum, Macrophomina phaseolina, Fusarium oxysporum, Helminthosporium sativum, and Aspergillus niger. The results clearly showed that, compared to the other Trichoderma species, TVK1 demonstrated the highest ability to suppress phytopathogens, with a growth inhibition rate of 2.48 cm per day. TVK2 grows at a rate of 1.96 cm per day, whereas TVK5 grows at a rate of 1.98 cm per day. The level of antifungal volatile organic compounds produced by TVK1 spores was higher against plant pathogens compared to the other species examined. This compound inhibits the growth of plant pathogens. T. harzianum can eliminate 100% of S. rolfsii pathogens and 100% of Alternaria sp. Pathogens were reduced by 92.02% for A. niger, 94% for F. oxysporum, 100% for P. aphanidermatum, 94.07% for H. sativum, and 100% for M. phaseolina. In a detached leaf assay, TVK1 inhibited the growth of pathogens in various plant leaves, including tomato, mustard, and eggplant, when compared to both the commercially available fungicide and the control. The study confirms that the isolate TVK1 can combat various phytopathogens. Early application of T. harzianum can reduce the risk of phytopathogenic attacks on leaves and promote plant growth.