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Distributions and Hosts of Armillaria Species in New York. J. T. Blodgett, Graduate Student, State University of New York, College of Environmental Science and Forestry, Syracuse 13210. J. J. Worrall, Assistant Professor, State University of New York, College of Environmental Science and Forestry, Syracuse 13210. Plant Dis. 76:166-170. Accepted for publication 23 August 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0166.

A statewide investigation was conducted to identify the species of Armillaria and determine their geographic distributions and host/substrate relationships in New York. At 273 sites, samples of rhizomorphs, wood, and/or basidiomata were collected from 414 trees, snags, stumps, or logs that were colonized by Armillaria. Field isolates were identified to species by mating the unknown isolates with previously identified haploid isolates. Six species were identified in New York forests. A. calvescens, the most common species, was widely distributed and had a broad host/substrate range. It occurred mainly on hardwoods (86% of collections), commonly causing butt rot. A. gallica, the second most common species, also was found primarily on hardwoods (86% of collections), especially oaks, and often caused butt rot. It was widespread but was not found in the Adirondack region. A. ostoyae, the third most common species, was found predominantly in the Adirondack region. It was the only species found principally on conifers (89% of collections). A. gemina was scattered throughout the state and was found almost always on hardwoods (96% of occurrences). A. sinapina, like A. ostoyae, was found mainly in the Adirondack region but was found mostly on hardwoods (60% of occurrences). A. mellea sensu stricto was found only once on Long Island on Quercus alba and once in central New York on an unidentified stump. All species except A. mellea were found infecting cambial tissue of living hosts. There was no significant difference among Armillaria species in the frequencies of cambial infections.