Canadian Forest Service Publications
Host-parasite relationships in the Hypoxylon canker of aspen. 1966. Hubbes, M. Breeding Pest-Resistant Trees : 229-238.
Issued by: Laurentian Forestry Centre
Catalog ID: 15367
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Pyrocatechol and two glycosides isolated from the bark of aspen (Populus tremuloides Michx.) were found to inhibit the growth of Hypoxylon pruinatum (Klotzsche) Cke. In tests with aspen bark extracts from two localities, inhibition was maximal in samples obtained in autumn and from the base of the trees. Inhibition of fungal growth was much stronger on bark meal than on media prepared from sapwood meal. The fungistatic action of pyrocatechol was reduced by bark cell elements when the chemical was incorporated in unautoclaved bark meal. In autoclaved bark meal its high fungistatic action was maintained. Fungal growth was strongly inhibited when the inoculum was placed on the living bark of fresh stem sections, whereas it grew well on sapwood. Evidence was obtained by isolation that H. pruinatum is established cankers invades xylem tissue for an appreciable distance beyond the external visible limits of cankers. It is concluded that H. pruinatum is a pathogen of sapwood and not of bark, as formerly believed.