This study provides new information on the distribution of the chestnut blight agent Cryphonectria parasitica and its vegetative compatibility groups (VCGs) in the Czech Republic. This study has revealed the presence of the disease in six localities. The VCG tests showed that each locality was represented by a single distinct VCG, which was different from the others collected in the country. The tests with 31 European testers of C. parasitica VCGs (EU-1 to EU-31) had assigned Czech isolates to VCGs EU-1, EU-4, EU-12, EU-13, EU-15, and EU-19. Moreover, the study showed that in the Czech Republic chestnut blight attacks young trees, not exceeding 35 years of age, and that climatic conditions in the country are suitable for C. parasitica. As two of the diseased localities were ornamental tree nurseries, one might expect its further spread over the country as a result of plant trade. The origin of infection remains unknown in all the localities where C. parasitica was detected.
New finds of Cryphonectria parasitica and the first record of chestnut blight on red oak Quercus rubra L. in the Czech Republic