Infection studies with Heterobasidion annosum on young trees of Picea abies

Infection studies with Heterobasidion annosum were carried out on 15-year-old, cloned spruces between 1971 and 1978. The inoculum was introduced into the sapwood of the test plants at the base of the stem. All inoculations, conducted at different times of the year, were uniformly successful. The pathogen spread through the xylem tissue rapidly during the vegetation period, but from early autumn onwards gradually disappeared over the following two years. After this period, the fungus could no longer be detected.