The Role of Host Vigour in the Susceptibility of Pines to Fomes annosus

Abstract

The resistance of suppressed pines to F. annosus and in particular the role of such trees as infection foci in disease-free stands is a matter of potential significance for the spread of the pathogen. Mycelial inoculations showed that, in contrast to dominant trees, the roots of very heavily suppressed trees possess no active resistance to the spread of the pathogen. However, at this extreme stage of suppression root-surface-fungi can also invade the roots and to a considerable extent replace the pathogen. Spore inoculations of small root wounds gave similar results except that the rate of infection was very much slower. Mycelial inoculations with F. annosus, Leptographium lundbergii, Peniophora gigantea, and Trichoderma viride were carried out in the trunks of pines suffering from different degrees of suppression. The fungi differed in their adaptation to the host, L. lundbergii being the most specialized to the biological, chemical, and physical characteristics of pine wood and T. viride the least. This adaptation was shown to be inversely related to the competitive saprophytic ability of each fungus, including the ability to produce and tolerate antibiotics.