| Abstract: | The effects of vitality fertilization on the growth of Heterobasidion annosum in roots of Norway spruce (Picea abies) were studied in a 53-year-old, naturally regenerated spruce stand in southern Finland. The fertilizer treatments were: (1), unfertilized control; (2), a compound fertilizer containing P, K, Ca, Mg, S, Cu, Zn and B; (3), as 2 with additional nitrogen; (4), as 3 with additional lime; and (5), a mixture composed on the basis of needle analysis, containing N, P, K and Cu. Three growing seasons after fertilization, four roots of eight trees in each treatment were inoculated with four different strains of H. annosum. Spread of the fungus from the inoculation point was determined after 12 months. Mean spread rates upwards in roots were 18.2, 25.6, 21.3, 26.0 and 29.8 cm/year in treatments 1, 2, 3, 4 and 5, respectively. These results suggest a tendency towards faster growth by H. annosum in fertilized trees. However, there was considerable variation in fungal growth at both the tree and root level and differences between treatments were not statistically significant. |
