Dual culture and VOC analysis reveal Trichoderma harzianum as an effective biocontrol agent against Fusarium oxysporum f.sp. ciceris on chickpea

Fusarium wilt, caused by Fusarium oxysporum f. sp. ciceris (Foc), is a major constraint in chickpea production in Turkey, leading to yield losses of up to 50%. This study aimed to characterize the morphological and molecular traits of Foc isolates and evaluate the antagonistic efficacy of three Trichoderma species under in vitro and greenhouse conditions. A total of 20 Foc isolates were obtained from diseased chickpea plants in Tarsus, Mersin, of which 10 were confirmed by PCR amplification of the ITS region. The isolates showed variation in colony morphology, spore type, and pathogenicity, with Foc8, 10, 14, 15 and 20 being the most virulent. Dual culture assays demonstrated that Trichoderma harzianum (T3) had the highest antagonistic activity, inhibiting mycelial growth of Foc isolates by up to 68%. Headspace GC–MS analysis indicated that T. harzianum VOCs were rich in antifungal ketones, in contrast to the alcohol- and acid-dominated VOCs of Foc. Greenhouse experiments revealed that T. harzianum not only suppressed disease development but also significantly enhanced chickpea growth by increasing root biomass, seed weight, and relative water content. These findings highlight T. harzianum as a promising biocontrol agent for the sustainable management of Fusarium wilt in chickpeas. Further field validation and formulation development are recommended to support its use in integrated disease management programs.