Pathological Studies on Polyporus rhodophaeus LÉV

Abstract

1. The present paper deals with the results of the writers' investigations on Polyporus rhodophaeus LÉV., which has been treated by many authors under the name of Polyporus semilaccatus BERK.
2. A number of broadleaf species are listed as hosts, and it has been reported that the fungus is found most commonly on various species of cherry trees in Japan. According to the writers' collections and observations, Robinia pseudoacacia is apparently one of the most susceptible hosts of the fungus.
3. In the present paper the morphological characters of the fungus as well as the diagnostic characters of decay in the wood of Robinia pseudoacacia affected by it were described. The investigations were mostly carried out on specimens which had been contributed to the writers' Herbarium from Sapporo in Hokkaido and Utunomiya in Totigi.
4. The decay of this plant caused by the present fungus starts from the sapwood and advances inward causing peripheral rot, but sometimes very irregularly, so that, while the central portion of the heartwood is attacked, there remain sound tissues in the outer portion. The rotted wood becomes soft and light, changing uniformly to whitish color.
5. By the characters of decay in the wood and also by the cultural experiment using BAVENDAMM'S method, the writers classified the fungus as belonging to the group of lignin dissolving fungi (Korrosionspilze).
6. The relation of temperature to the growth of the fungus was studied by growing the mycelium on poured plates of apricot decoction agar, of potato decoction agar and of soy agar incubated at different temperatures. It was found that the fungus in culture grows at from ca. 11°C to ca. 40°C and the optimum temperature for the mycelial growth seems to lie at approximately 31°-32°C.