The development of population structure of Cryphonectria parasitica on European chestnut (Castanea sativa Mill.) in the Experimental Castanetarium Horné Lefantovce, observed over a 12-year study period

: We studied occurrence of chestnut blight disease in the Experimental Castanetarium Horné Lefantovce, SW Slovakia. The study ran in years 2006-2007 on a set consisting of 889 chestnut trees growing in the clonal orchard on Biological Plot 105. From this number, 857 trees were found healthy without disease symptoms. The chestnut blight disease was identified on 32 of them. The infected trees were examined for presence of pycnidia and perithecia of the causal agent. In all positive cases, the observed morphological characters indicated virulency of the obtained isolates. No hypovirulent isolate was detected on the evaluated experimental plot. In total, six vegetative compatibility (vc) types were specified in the sample consisting of 31 isolates. Our vc types corresponded to the European vc types EU 2, EU 12, EU 13, EU 14, EU 17, EU 19. Two vc types - EU 2 and EU 19 - were dominant. Vc type EU 19 accounted 35.5% and EU 2 32.2% of isolates. The vc type EU 19, which was the most frequent one in the evaluated site, was detected in Slovakia for the first time.