Armillaria root rot: Influence of soil nutrients and pH on the susceptibility of conifer species to the disease¹

Abstract

Abstract Seedlings growing on soil with nutrient deficiency and a lower pH were smaller and less vigorous than the seedlings growing on non‐deficient soil with a comparatively higher pH. A higher percentage of roots and seedlings were infected and more seedlings died on soil with nutrient deficiency and a lower pH than on non‐deficient soil with a higher pH. Non‐vigorous seedlings also contacted infection earlier and showed more mycelial growth than the vigorous seedlings. Roots of vigorous seedlings showed more resinosis and callus formation, indicating resistance during the establishment of the fungus on the host. Alterations in the level of nutrients in vigorous and non‐vigorous infected seedlings were generally similar.