Armillaria species associated with Gastrodia elata in Japan

Summary Gastrodia elata was collected from July to August 1992 in Hokkaido forests. A total of 22 diploid isolates were paired with haploid testers of the biological Armillaria species reported in Hokkaido. One isolate was identified as A. ostoyae, 10 as A. gallica, three as A. jezoensis, three as A. sinapina, and five as A. singula. These isolates were compatible with the respective Hokkaido testers of these species. With the exception of A. ostoyae, these species are known as saprophytes, which form abundant rhizomorphs in soil. Clear isozyme profiles of esterases were obtained with all isolates except one. Interspecific variations were more important than intraspecific variations. The esterase profiles could be used for identification of the Armillaria species in Hokkaido as a useful complement to the mating‐type method.