Roots of salal (Gaultheria shallon Pursh) collected from forest clearcuts were examined by light and scanning electron microscopy, and the ericoid mycorrhizal fungi were isolated and identified. Heavy colonization of typical ericoid mycorrhizae was present in and restricted to the first of the two layers of root cortical cells. Neither ectomycorrhizae nor arbutoid mycorrhizae were observed. In the field, over 85% of the roots and 90% of the cortical cells within colonized roots were colonized. One hundred and seventy-five of the 278 fungal isolates from salal roots formed ericoid mycorrhizae with salal in the laboratory, and these isolates were grouped into four species based on spore formation and cultural characteristics: Oidiodendron griseum Robak, Acremonium strictwn W. Gams, and two unidentified, nonsporulating fungal species. The association in the laboratory between A. strictum and salal was atypical in that the fungus improved the growth of salal seedlings but was slow to colonize roots and occasionally grew and even sporulated on the shoots. No differences in percent colonization or diversity of ericoid mycorrhizal fungi were found in salal growing on clearcuts from two different forest types. Keywords: Gaultheria shallon, Oidiodendron griseum, Acremonium strictum, ericoid mycorrhizal fungi.
Hypholoma fasciculare (Huds. ex Fr.) Kummer was paired with Armillaria ostoyae (Romagn.) Herink in a variety of ways in the laboratory and then it was inoculated onto A. ostoyae infected stumps in the field. The ability of H. fasciuclare colonies to overrun A. ostoyae colonies in culture was confirmed. Hypholoma fasciculare fully colonized discs of tree roots where A. ostoyae was well established, and prevented A. ostoyae from occupying root segments when both fungi were introduced simultaneously. A simple method for inoculating H. fasciculare into stumps is described, and data supporting successful field inoculations are presented. The ability of H. fasciculare to invade freshly killed stumps, even those occupied by Armillaria, is demonstrated, and it is speculated that the ability of this saprophyte to invade fresh stumps is dependent upon its inoculum potential.
Armillaria ostoyae (Romagn.) Herink. causes serious damage to forest tree species worldwide. In this study, Hypholoma fasciculare (Huds. ex Fr.) Kummer was inoculated, after logging, into areas in south-central British Columbia that had been identified as having high levels of A. ostoyae. Hypholoma fasciculare was successfully established in a variety of different types of trials, as indicated by growth of H. fasciculare mycelium into roots of inoculated stumps and the presence of fruiting bodies on and around stumps. Three to five years after treatment, inoculated plots had biologically and statistically significantly lower levels of mortality attributable to A. ostoyae.Résumé : L'Armillaria ostoyae (Romagn.) Herink. cause de sérieux dommages chez plusieurs essences forestières, un peu partout au monde. L'auteur a inoculé l'Hypholoma fasciculare (Huds. ex Fr.) Kummer., après la récolte forestière, dans des régions du centre-sud de la Colombie-Brittanique où on observe de fortes densités de l'A. ostoyae. Le mycé-lium de l'H. fasciculare a été introduit avec succès suite à un ensemble de différents types d'essais, tel que révélé par la croissance de l'H. fasciculare dans les racines des souches inoculées et la présence de basidiomes sur et autour des souches. De 3 à 5 ans après le traitement, les parcelles inoculées montrent un degré significativement moindre de mortalité attribuable à l'A. ostoyae, au plan statistique aussi bien que biologique.Mots clés : Hypholoma fasciculare, armillaire, maîtrise biologique, débris ligneux.[Traduit par la Rédaction] Chapman et al. 969
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