XVI International Botanical Congess

Field study has shown that necrotic lesions begin forming on the twigs from July. However, the development of necrotic lesions on the infected twigs ceases between August(summer) and October(autumn). The main purpose of this study was to closely investigate the reaction of host tissue to invasion by Stromatinia cryptomeriae and subsequent lesion development. On the incipient lesions in July, the collapse of both palisade tissue and spongy tissue was observed by light microscopy. In the necrotic lesions in October, however, the continuous formation of cork tissue was observed surrounding the dead tissue. It is suggested that the cork tissue provides a defense barrier to expansion of the necrotic lesions.