Oidiodendron mains Barron, Scytalidiutn vaccinii Dalpé, Litten, & Sigler, and a variable white taxon (VWT) were isolated consistently from the roots of ericaceous plants collected in three different habitats. Restriction fragment length polymorphism data were used to (i) clarify the identification of strains of O. maius with character states intermediate between O. maius and Oidiodendron griseum Robak, (ii) identify the VWT as distinct from S. vaccinii in spite of cultural similarities, and (iii) reveal that S. vaccinii comprises two genotypes correlated with habitat. Corn meal agar was used to induce conidiogenesis in S. vaccinii, and one strain produced apothecia consistent with the description of Hymenoscyphus ericae (Read) Korf & Kernan, confirming the anamorph–teleomorph relationship of these two taxa. Oidiodendron maius and S. vaccinii, already accepted as mycobionts of the Ericaceae, are confirmed as ubiquitous in natural habitats of Alberta and are often both isolated from the same root fragment. The isolation of Phialocephala fortinii Wang & Wilcox, a non-mycorrhizal endophyte of diverse plant families, from two of the sites but not from the acidic wetland indicates that its distribution depends on edaphic factors. Its vigorous growth on the initial isolation plates adversely affected the recovery of the other three taxa. Key words: ericoid mycorrhiza, Ericaceae, RFLP, Oidiodendron, Scytalidium, Hymenoscyphus, Phialocephala.
Attempts to eliminate Oidiodendron minus Barron from the substrate of Agaricus cultures
