Transfer of the P-type of Heterobasidion annosum from old-growth stumps of Picea abies to Picea abies and Larix X eurolepis.

摘要

The infection of P. abies and LarixXeurolepis by H. annosum was studied in felled trees in Sweden. Thinnings were carried out in stands of LarixX eurolepis, 15 and 20 years old, and in a 25-year-old stand of P. abies, established on a site heavily infected by H. annosum. The 15- and 20-year-old LarixXeurolepis stands exhibited the greatest incidence of butt rot with infections amounting to 38 and 57%, respectively, of removed trees. The incidence of butt rot in the P. abies stand was only 5%. H. annosum was the main butt rot causing fungus. All isolates of H. annosum were of the P-intersterility group. Transfer of H. annosum from old-growth P. abies stumps to trees felled in the thinning of the next generation was demonstrated by somatic incompatibility tests. However, the majority of infections could not be connected with decay already established in the previous generation. In LarixXeurolepis, rot columns were frequent, also including several genotypes in the same stem, and typically positionedin the inner sapwood. The few infections of P. abies were situated in the heartwood.