SUSCEPTIBILITY OF WHITE SPRUCE TO POLYPORUS TOMENTOSUS IN HEALTHY AND DISEASED STANDS

Abstract

Roots of white spruce (Picea glauca (Moench) Voss) in areas affected by stand-opening disease were not more susceptible than those in healthy stands when inoculated with Polyporus tomentosus Fr. The percentages of inoculated roots infected in heavily diseased, lightly diseased, and healthy stands were 23, 25, and 25% respectively. Although more roots on suppressed trees were infected than on dominant trees as a result of inoculation, these differences were significant in only three plots. Ten-month-old inoculum caused significantly more infections than 6-month-old inoculum. The pH of the upper mineral soil horizons (A2 and B) did not influence infection or early disease development in inoculated roots.