Armillaria mellea sensu stricto (Vahl:Fr.) Kummer has been found infrequently in studies conducted in northeastern North America (2) and it was not found in an earlier survey of northern Ontario (3). In a 1999 survey of Armillaria spp. conducted in central and southern Ontario, A. mellea s. str. was found at four of 110 locations surveyed, two approximately 100 km west and southwest of Ottawa, one 15 km north of Belleville, and one on the Niagara Peninsula in the Balls Falls Conservation Area. At the Ottawa area sites, A. mellea s. str. was found on red oak (Quercus rubra L.) and beech (Fagus grandifolia Ehrh.) stumps. A. ostoyae (Romagn.) Herink and A. gallica Marxmuller & Romagn. were also found on these sites. At the Belleville site, it was found on a dead co-dominant white birch (Betula papyrifera Marsh.), while at the Niagara Peninsula site it was found on a dead, suppressed beech. A. gallica was also found at these latter sites. Sites ranged from moisture regimes fresh to moist, and from sandy to silty soil from both calcareous and non-calcareous parent material. Four isolates were obtained from infected wood and rhizomorphs and identified by the polymerase chain reaction, yielding restriction fragment length polymorphism (RFLP) products of 500 and 183 base pairs. These fragment sizes are similar to findings reported in an earlier study (4). The identification was confirmed by haploid/diploid pairing. The Balls Falls Conservation Area is in close proximity to extensive fruit orchards and the presence of A. mellea is cause for concern, especially in light of its proven pathogenicity to fruit trees (1). This is the first confirmation of A. mellea s. str. in Ontario.
References: (1) J. E. Adaskaveg and J. M. Ogawa. Plant Dis. 74:341--352, 1990. (2) J. T. Blodgett and J. J. Worrall. Plant Dis. 76:166--170, 1992. (3) M. T. Dumas. Can. J. For. Res. 18:872--874, 1988. (4) T. C. Harrington and B. D. Wingfield. Mycologia 87:280--288, 1995.