Vertical Spread of Heterobasidion annosum in Stems of Norway Spruce : Root and Butt Rots

Uppsala

International Union of Forest Research Organizations, Swedish University of Agricultural Sciences

1994

S. 208-211

20 Lit. Ang.

Bandaufführung

13462

73462

The main objective of this infection experiment was to demonstrate rate of spread, differences in resistance in trees within a stand and differences in pathogenicity between isolates of Heterobasidion annosum. In an infection experiment 16 spruce trees were inoculated, each with four different isolates of Heterobasidion annosum (S-type). Increment borings were made at four different heights above ground level, 0.3 - 1.3 - 2.3 - 3.3m, where artificially infected bore cores were aseptically inserted. The trees were felled after one year, cut into sections and examined for the presence of the fungus by growth of conidiophores and isolations. The average vertical spread upwards in the trunk was 18.5cm. In 64% of the cases the fungus was detected in the wood after 1 year. Including only inoculations where reisolation of Heterobasidion annosum was successful, the annual spread was 28,9cm. Significant differences (P=0.003) between trees as to vertical spread were found. Differences in the vertical spread of Heterobasidion annosum observed between isolates (P=0.30) and between different inoculation heights (P=0.08) were non-significant. The presence of Ascocoryne spp. appeared to inhibit the development of Heterobasidion annosum. The results indicate that between-tree variation in resistance might be genetically controlled and thus of significance in tree-breeding programs.