Abstract
In order to clarify the etiology of acorn decay in Quercus serrata and Q. crispula, we studied the pathogenicity of Ciboria batschiana to acorns of these species and the incidence of infection in oak forests. The acorns of Q. serrata and Q. crispula were inoculated with fungal cultures of C. batschiana. Lesions on cotyledons and pseudosclerotia formation were noted in both species after the inoculation. The inoculated fungi were re-isolated and it was confirmed that C. batschiana was pathogenic to acorns of Q. serrata and Q. crispula. In 2 forests of Q. serrata in Iwate Prefecture in northern Japan, acorns were dispersed in late September, when apothecia occurred, and partial decay was manifested as lesions on the surface of cotyledons in acorns in October; most of the infected acorns formed pseudosclerotia in April. This suggests that C. batschiana infects and induces lesions on the cotyledons of acorns in autumn and induces complete decay and pseudosclerotia formation during winter.
