Cryphonectria parasitica is a pathogenic fungus that causes bark necrosis of chestnut (Castanea) and oak (Quercus) species, It was introduced into Europe from the USA in the middle of the last century and caused a lot of damage to infected plants. In the 1980s, a virus-like particle (VLP) was discovered in the fungus that significantly affected the virulence of virulent fungal strains. The mycovirus contains a double stranded RNA and does not form a coat of protein. In that case when the hypovirulent and virulent fungal strains are vegetatively comaptible, they belong to the same VC group, they are able to transfer the dsRNA through hypha-anastomosis. The curative use of hypovirulent strains of the fungus (infected with mycovirus) proves to be the most effective defense protocol in the fields. The preventive use of hypovirulent strains in a biological lant protection program is a completely new field. Thus, it became possible to create opportunities for the production of “immunized” seedlings.

The upcomiong challenges in plant protection activities require the development of ecological-based, biological solutions. One good practical example of this is the field use of hypovirulent fungal strains to cure older, diseased chestnut trees. With our research, we would like to expand this technology of biological plant protection to a new application that can also be used on oak trees.

Keywords: biological plant protection, chestnut blight fungus, Cryphonectria parasitica, oak