Biocontrol potential of endophytic <i>Trichoderma</i> sp. against the pathogenic fungus, <i>Alternaria alternata</i> that causes leaf spot in tomato plants

This study was aimed at evaluating the two isolates of the bio-resistant fungi, Trichoderma harzianum and T. koningii in management of the fungus that causes Alternaria alternata leaf spot disease in tomato plants by inducing systemic resistance in the plant. It was demonstrated that two isolates of the pathogenic fungus, A. alternata could infect tomato seeds on water agar media. Isolate No. 1 was the most successful, with an infection rate of 63%, while isolate No. 2 achieved an infection rate of 56%. When employed in concentrations of (10, 20, or 30%) with PDA culture medium, bio-resistant fungus filtrate demonstrated suppression of the pathogenic fungus A. alternata, with the enhanced levels of inhibition with increasing concentration used. Oxacycloheptadec-8-en-2-one, compound 9,12-Octadecadienoic acid, methyl ester, and many more chemical compounds with the ability to inhibit fungi were discovered via the use of the GC-MS equipment to analyze the fungal infiltrates produced by T. harzianum and T. koningii. The bio-resistant fungi significantly lessened the severity of the infection caused by the pathogenic fungus, A. alternata, reaching a reduction of 33.81% during treatment with T. harzianum as opposed to injury of 56.855% in pathogen alone. The tomato leaves that were treated with T. konhngii produced the maximum phenolic content (0.56 mg/g).