Chestnuts (Castanea spp.) are widely cultivated in Europe, the United States, and some parts of Asia for their culinary and therapeutic properties, as well as their contributions to biodiversity through hardwood forests. However, chestnut productivity is severely threatened by both abiotic and biotic factors, with chestnut blight disease caused by Cryphonectria parasitica being the primary biotic threat. European chestnut (Castanea sativa), a valuable species grown in Hungary, has been heavily impacted by this disease, with 50% of orchard trees dying since its introduction in 1960.

Molecular identification is crucial for understanding the genetic diversity and phylogenetic analysis of C. parasitica and tracking its spread. Using ITS and TEF primers, we confirmed the presence of C. parasitica in our collected samples. Due to the limited efficacy and environmental concerns of chemical fungicides, biological control methods are increasingly being explored. Hypovirulent strains, characterized by their white mycelia and the presence of mycovirus in their cytoplasm, have shown high potential for controlling chestnut blight. In our study, we tested eight different Trichoderma species against both virulent and hypovirulent strains of C. parasitica. Six species exhibited significant biocontrol activity and inhibited the pathogen’s growth, including the virulent and hypovirulent samples, indicating the effectiveness of Trichoderma as a potential biological control agent.

Our findings highlight the potential of integrating molecular techniques and biological control strategies, such as the use of hypovirulent strains and Trichoderma species, to manage chestnut blight effectively, reducing the reliance on chemical fungicides and promoting the health and productivity of chestnut trees in both agricultural and natural ecosystems.