Since 1967 when chestnut blight (Cryphonectria parasitica) was observed for the first time in Albania several field surveys have been carried out in chestnut (Castanea sativa) stands and have emphasized the widespread presence of the disease. About 30% of surveyed trees showed different stages of decline. Different proportions of C. parasitica morphotypes (normal/orange, intermediate, white) were detected when isolates were grown on agar media in the laboratory. About 57% of isolates showed normal pigmentation suggesting virulence, while 42% showed intermediate morphology. Less than 1% (or five isolates) was identified as hypovirulent based on detection of dsRNA of virus. Five European vegetative compatibility (vc) groups, EU-1, EU-2, EU-3, EU-10 and EU-12 were identified in four districts (Pogradec, Tropoja, Tirana and Librazhd) with dominant chestnut forests. EU-12 was the dominant vc type making up 39% of isolates studied. Transmission of dsRNA between virulent and hypovirulent isolates was successful in laboratory conditions. Biological control using hypovirulent strains to inoculate virulent cankers on chestnut trees in the field yielded between 46 and 84% of heavily calloused cankers, while around 30% of healthy trees that had not been inoculated produced heavily calloused cankers, suggesting natural spread of hypovirulence.
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