Pathogenicity of Ophiostoma polonicum to Norway spruce. The Effect of Isolate Age and Inoculum Dose

1991

11 S.

2 Abb., 2 Tab., 14 Lit. Ang.

Bandaufführung

37938

Inoculation experiments in order to test the pathogenicity of Ophiostoma polonicum to Norway spruce have given variable results. An experiment was designed to test if the age of the fungus isolate and the inoculum dose could explain some of this variation. Thirty spruce trees were inoculated with 0-, 1-, and 3-yr-old isolates of O. polonicum in two or four rings of inoculation points 100-145 cm above ground. The trees were harvested 40 days after inoculation, and resin flow, bark necroses and blue-stained sapwood were measured. There was no effect of isolate age. The cross-sectional proportion of blue-stained sapwood was about doubled with a dose of four rings of inoculations points as compared to two rings. Individual variation in resistance between trees and inoculation points was strongly correlated to resin flow.