Assessment and characterization of Turkish hypovirulent isolates of Cryphonectria parasitica (Murr.) Barr.

Hypovirulent isolates of Cryphonectria parasitica on chestnut trees were collected from abnormal cankers in eastern and western Turkey. Laboratory tests showed differences between these isolates in morphological and physiological characters and in their virulence in culture. The majority of selected isolates of C. parasitica contained dsRNA, but some of the hypovirulent ones were dsRNA-free. The decrease in damage severity in Turkey is possibly a consequence of the occurrence of hypovirulent isolates and the biological control resulting from their natural spread.