Production and Dispersal of Ascospores in Eutypa Armeniacae

Abstract

Perithecia and ascospores of E. armeniacae may be produced on dead apricot wood for at least 5 years following maturation of the first stromata. Each winter, a stroma may produce new perithecia between the exhausted ones of the previous year. Results from a three-year quantitative study of the seasonal abundance of airborne ascospores show that, in South Australia, there is a winter period of low ascospore frequency which coincides closely with the dormant period of the apricot host. Abundant ascospore release follows rainfall exceeding 0·05 in. at other times of the year. The pattern of ascospore release, when related to natural rainfall in field tests and to moisture supply in laboratory tests, gives no evidence of diurnal periodicity.