Colonization of beech leaves by two endophytic fungi in northern Japan

Leaves of Japanese beech (Fagus crenata) were collected monthly during the vegetation period at five sites in the Tohoku district in Japan to isolate endophytic fungi. Leaves were also collected only once at two additional si tes. Two endophytic fungi were dominant, a Discula species and a sterile my celium. This result strongly suggests that these two fungi are generally as sociated with leaves of the Japanese beech at different sites. At most site s the isolation frequency of Discula sp. was greatest in June and gradually decreased from July to October whereas the isolation frequency of the ster ile mycelium increased during the vegetation period and remained at a high isolation frequency in October. Spores of Discula sp. were released for a v ery short time in late May, just after the disappearance of the snow cover on the forest floor. These spores may be important for the infection of new ly sprouting leaves.