Armillaria root disease, stand characteristics, and soil properties in young lodgepole pine.

Abstract Thirty six lodgepole pine stands in west-central Alberta, ranging in age from 9 to 28 yr of age, were surveyed for Armillaria root disease mortality. Selected stand characteristics and edaphic factors were recorded in each stand to determine if there was a relationship between these factors and Armillaria root disease. Data was analysed using a multivariate linear regression. A statistically significant relationship was found between sand content, ammonium (NH 4 + ) concentration and Armillaria root disease. The incidence of Armillaria root disease increased significantly with increasing sand content of the surface mineral horizon and decreasing NH 4 + concentration of the surface organic horizon (LFH). Stand age, density, elevation, soil pH, depth of the surface organic horizon (LFH), calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), and sulfur (S) did not have a significant effect on the amount of mortality.