The blister rusts, which are known as the most destructive disease of five-needle pines in Europe and North America, have often been recorded in Japan. To clarify the taxonomic position of the causal fungi, morphological observations, inoculation experiments, and cytological observations of many specimens collected from various locations were carried out. As a result, the blister rust fungi of five-needle pines in Japan were classified into one species of Cronartium, and two species and one variety of Endocronartium, including new species. Based on the results of identification of specimens examined and field surveys, the geographic distribution of blister rust sepcies in Japan is reconsidered and discussed.

　Six biological species including two new species and one new subspecies of Armillaria mellea sensu lato from Hokkaido were identifed: A. ostoyae, A. gallica, A. jezoensis, A. sinapina, A. singula, and A. mellea subsp. nipponica. The morphological characteristics of the basidiomes were examined and Japanese names were confirmed. Symbiotic associations of the biological species with Gastrodia elata and Galeola septentrionalis, and mycoparasitic associations with Rhodophyllus abortivus were also identified in this study.