Turkish Heterobasidion abietinum is pathogenic to inoculated Abies nordmanniana ssp. nordmanniana and ssp. bornmülleriana

Four‐year‐old seedlings of Abies nordmanniana ssp. bornmülleriana and 5‐year‐old seedlings of Abies nordmanniana ssp. nordmanniana were inoculated on the lower stem with 28 Heterobasidion abietinum isolates originating from four different regions of Turkey. Replicate seedlings were incubated in greenhouse and growth chamber. After 7 weeks, infection incidence, mortality, lesion length in the inner bark and fungal growth in the sapwood were examined. Infection incidence in different host–incubation combinations ranged between 70.5 and 79.5% and the average mortality rate was 4.2%. Average lesion lengths varied between 8.4 and 33.9 mm, and average fungal growth between 18.7 and 34.8 mm. There was a significant positive correlation between lesion length in the inner bark and fungal growth in sapwood on both hosts and conditions. Clear differences in virulence between H. abietinum isolates originating from different regions were not found. The results indicate that H. abietinum is pathogenic on both investigated subspecies of A. nordmanniana. Both lesion length and fungal growth were greater on ssp. bornmülleriana, indicating that it would be more susceptible than ssp. nordmanniana.