Armillaria species of the Olympic Peninsula of Washington state, including confirmation of North American biological species XI

Forty-eight collections of Armillaria from the Olympic Peninsula of Washington State were identified to species using the conventional pairing protocol and/or a polymerase chain reaction-based (PCR) technique utilizing restriction fragment polymorphisms (RFLPs) of the intergenic spacer region (IGS) of the ribosomal DNA. The PCR-based technique yielded results comparable to those obtained by the conventional pairings. Several restriction patterns not previously reported in North American isolates were found using the enzyme Alu I. Collections from eight different host species were identified as A. ostoyae, A. sinapina, A. nabsnona, A. gallica, or North American biological species (NABS) XI. Armillaria ostoyae, A. sinapina, and A. nabsnona were the most often collected, with the first two occurring predominantly on gymnosperms and the latter mostly on angiosperms. Armillaria gallica and NABS XI were collected rarely and only from angiosperms. This is only the second report of the occurrence of NABS XI.