2017 Volume 21 Issue 1 Pages 1-7
Sydowia japonica is a pathogenic fungus of the male strobili of Cryptomeria japonica. The fungus is expected as a biological control agent for pollinosis of Japanese cedar to inhibit the anthesis of male strobili. We investigated the rate of infection of S. japonica in male strobili cluster and the isolation frequency from the infected male strobilus to obtain the fundamental information to evaluate the substantivity of efficacy and the possibility of secondary infection in the natural environment. Although the number of male strobili and the infection rate varied widely at each study site, the number of current-year-infected male strobili positively correlated with the number of current-year-produced male strobili and the number of previous-year-infected male strobili, respectively. It is believed that the infection number in the current year depends on both the amount of the infectious source and the amount of new host tissue. The results showed that S. japonica could survive for more than two years in the natural condition.
