Abstract
Bed-logs for the Shiitake (Lentinula edodes) mushroom cultivation were inoculated with the suspension of Graphostroma platystoma ascospore using various inoculation methods. The rate of stroma formation in each method was evaluated to elucidate the location of the invasion of G. platystoma in the bed-logs [the rate of stroma formation (=stroma rate): a ratio of areas with stromata to total surface area of the bed-logs]. Wounds inflicted through bark to sapwood are required for the ascospores to invade the bed-logs. The relation between the timing of inoculation with the ascospores and the rate of stroma formation was also examined. A high rate of stroma formation was scored when bed-logs were inoculated with the ascospores one month before the inoculation of the Shiitake spawn or simultaneous inoculation with the spawn. However, the rate of stroma formation was low when the ascospores were inoculated two months after the inoculation with the spawn. These results suggest that the ascospores invade bed-logs during early periods of inoculation season of the Shiitake spawn. After the inoculation of the ascospores to live Quercus acutissima trees in the spring, the trees were cut down during winter of the same year, inoculated with the Shiitake spawn and incubated in a standard cultivation protocol. In this case the high rate of stroma formation in the bed-logs was observed. These results suggest that the ascospores are capable of invasion and inhabitation even on live trees.
