Biological Control of Cryphonectria parasitica in Romanian Protected Sweet Chestnut Forests

Abstract

Asiatic fungus Cryphonectria parasitica has gradually infected all chestnut habitats, forest and horticulture plantations from the most important natural centres of sweet chestnut distribution in Romania. The objectives of this work were to understand the destruction rate of chestnut habitats under C. parasitica pressure, and to test the efficacy of pathogen control in revitalizing these protected forests. Successive inventories of forest health status were carried out in forest districts of Maramures and Gorj counties. C. parasitica biologic control using CHV1 virus has been tested. The methodology includes standard laboratory and field work techniques: local hipervirulent strain identification and conversion to hipovirulence, field canker inoculation, and treatment efficacy evaluation. The fungus killed all mature chestnut trees in roughly two decades. Field inoculation has been successful on chestnut and sessile oak (fungus secondary host) in experimental plots from both target zones. This is the first time in Romania when a forest habitat is recovered by means of biological control, after a severe dieback of the old forest caused by a lethal invasive pathogen.