ABIES SIBIRICA IN THE URAL REGION IS ATTACKED BY THE S-TYPE OF HETEROBASIDION-ANNOSUM

Specimens of Heterobasidion annosum were collected in seven mixed stan ds of Abies sibirica and Picea abies in Yekaterinburg and Perm regions on the western side of the Ural Mountains, Russia. Pure cultures were isolated From 60 collections and identified in mating rests. Only the S intersterility group was found, attacking both fir and spruce. Base d on the appearance of clamp connections in matings, the compatibility of 12 homokaryons from the Ural area with 14 S group homokaryons from western Europe was 100%, with 13 F group homokaryons from southern Eu rope 76% and 9 P group homokaryons from western Europe 3%. The results show that A. sibirica, in contrast to A. alba, is very susceptible to the S type H. annosum.