Succession of microfungal flora on Rodgersia podophylla plants at the forest side of Cryptomeria plantation

Microfungal flora on aerial parts of a forest floor plant, Rodgersia podophylla, were studied at the forest side of a Japanese cedar plantation. From May to October, Nigrospora spp. were dominantly isolated from leaves, whereas Acremonium spp. and Fusarium spp. were dominant on stems, suggesting that the aerial part of the plants about 1m height can offer two different habitats for these dominant fungi. In September and October, we could easily discern different types of tissue on the withering leaves, i.e., brown (necrotic lesion), yellowish (border tissue between brown and green areas), and green (healthy tissue). Nigrospora spp. and Pestalotiopsis spp. were continuously isolated on the brown area as well as on green and yellowish areas. Pathogenicity of N. sacchari and P. neglecta on potted plant leaves was confirmed by inoculation. From these, the fungi of these two genera seemed to have changed from quiescent to pathogenic with leaf senescence. Sporulations by fungi of the two genera were recognized on overwintered stems. These fungi may overwinter in stems that are slow to decompose, and seem to go over to the leaves in the following spring. Thus, they could be candidates for parasites that may play an important role in decomposition of the plant.