Scleroderris canker damage in 1983 and Scleroderris canker/frost damage in 1985 were investigated in fertilizedPinus sylvestrisandPinus contortastands on an ombrotrophic mire in central Finland. Severe Scleroderris canker damage in 1983 was clearly associated with fertilization, especially NPK, both in Scots pine and lodgepole pine stands. The effect of fertilization on Scleroderris canker/frost damage in 1985 was not as clear as in 1983. Lodgepole pine was more susceptible to damage compared to Scots pine. Predisposition to Scleroderris canker and frost damage seemed to be associated with increased growth. Predisposition could not be interpreted by means of needle nutrient concentrations although boron concentrations were lower on fertilized plots compared to control plots.