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Disease development and severity of Scleroderris canker of Todo-fir in Hokkaido, Japan, vary according to forest type. The occurrence and severity of Todo-fir canker caused by Scleroderris lagerbergii, were compared in plantations with and without a deciduous canopy. Planted Todo-fir under cover remained mostly healthy, whereas in the open they were severely damaged. This suggests a protective effect by the upper deciduous species against the development of canker. The authors suggest that the cover of deciduous species affects such microclimatic conditions as minimum temperatures and snow deposit in early winter creating more favorable conditions for Todo-fir planted under cover than in the open.

This article examines ascospore and pycnospore discharge and germination. The causal fungus was psythrophilic, with an optimum growing temperature of 10 degree Celsius. Pathogenicity to Abies sachalinensis was ascertained by artificial inoculation and symptoms were induced also by spraying a pycnospore suspension on to untreated shoots. Results of inoculation-experiments using both mycelium and pycnospore suspensions were always positive. On shoots inoculated in autumn, lesions were produced in the following spring. The lesions were larger when the inoculated shoot was first damaged with dry ice.