Abstract

Early blight disease, which is caused by Alternaria solani, is a major yield-reducing disease of eggplant (Solanum melongena L.) with losses of up to 35-78 % recorded in a favorable environmental setting. The excessive use of synthetic fungicides has cultivated resistance and environmental issues; this has necessitated alternative, sustainable types of fungicides. The objectives of this study were to design and test an effective biofungicide against early blight in eggplant using Iraqi fungal isolates under Iraqi climatic conditions. The healthy rhizosphere of eggplant was collected in five governorates of Iraq and fungal isolates were performed 247 through selective enrichment methods. Morphological and molecular identification by ITS1-5.8S-ITS2 rDNA sequencing showed Trichoderma harzianum isolate EG-TH-23 to be the best antagonist that inhibited A. solani by 89.4% in dual culture assays. Response surface methodology was used to optimize the bioformulation, and stable liquid formulation with 10 8 CFU/mL, 0.3 % carboxymethyl cellulose, and 0.15 % Tween-80 was achieved. Biofungicide was tested in field trials in both successive seasons (2024-2025) and was found to have the same level of control efficacy as a commercial fungicide Mancozeb (84.7%). The treatment also led to a significant improvement of the plant growth parameters wherein the fruit yield was 42.3 % higher than the untreated controls. The residue analysis revealed that there were no detectable chemical residues on fruit treated and the costbenefit revealed that there was 3.2:1 investment reimbursement. Stable viability of 12 months at a 4 o C storage was observed through shelf-life studies. The native biofungicide suggests an attractive, eco-friendly method of early blight control in an eggplant cropping system, with efficacy within a similar range to conventional products but supporting the application of integrated pest management in the Middle East agricultural ecosystem.