Das Projekt "Chestnut blight research in the Balkans and Georgia: population studies and biological control methods" wird vom Umweltbundesamt gefördert und von Eidgenössische Forschungsanstalt für Wald, Schnee und Landschaft durchgeführt. Lead Chestnut blight caused by the fungus Cryphonectria parasitica is an introduced disease responsible for a widespread decline of European chestnut forests. In this project, we aim to provide the scientific basis for biological control of this devastating tree disease. Background Biological control is a highly desirable means of pest and disease management in natural and managed forest ecosystems. This control method depends on the invasion of a pest population by a biocontrol agent (e.g. a hyperparasite), which ideally can spread and establish in a self-sustainable way. The Cryphonectria hypovirus1 (CHV-1) infects the chestnut blight fungus C. parasitica and has the potential to be used as a biological control agent of this pathogen. The invasion of C. parasitica populations by the hypovirus appears to be highly influenced by the population biology of the fungus. Spread of the hypovirus is favoured by low diversity of vegetative compatibility (vc) types and limited sexual reproduction. Therefore, the information and understanding of the population structure and epidemiology of C. parasitica and the hypovirus is important for the success of biological control of chestnut blight. Objectives The project has two main objectives, (1) to investigate the population structure and colonization history of the chestnut blight fungus C. parasitica in Georgia and the Balkans by using different types of genetic markers, and (2) to evaluate novel application methods and perform practical biological control experiments in collaboration with end users. Significance European chestnut is an important multipurpose tree species grown for fruit and wood production in many rural areas of Europe. Our project will contribute to a better understanding of a serious disease of chestnut trees and will help to restore and protect infested chestnut orchards and forests. This multilateral project will also allow the continuation and strengthening of partnerships among research groups from Switzerland, Macedonia, Croatia, and Georgia.