Susceptibility of Picea abies and Pinus sylvestris Seedlings of Various origins to Heterobasidion annosum and H. parviporum

Five-year-old Norway spruce and four-year-old Scots pine seedlings of various origin were inoculated with Heterobasidion annosum s.s. and H. parviporum to estimate whether the susceptibility of seedlings to Heterobasidion was affected by origin of seeds. In total, 520 spruce and 538 pine seedlings from different seed sources and provenance regions of Latvia were tested. Four months after inoculation the fungal growth was measured. The results highlight differences between development of H. annosum and H. parviporum in spruce and pine seedlings. We did not find any seed source that was more resistant than others.