부산대학교 도서관

A decrease in the epidemic of European chestnut blight coincided with the spread of hypovirulent isolates of Cryphonectria parasitica. These isolates contained viral double-stranded RNAs which, when transmitted by hyphal anastomoses to mycelia of "normal" pathogenic isolates, modify their morphology and attenuate their pathogenicity. The distribution of these hypovirulent isolates in Italy is, however, not uniform. In some areas, hypovirulent isolates seem to predominate, while, in others, the virulent form prevails.