Environmental Factors Affecting Maturation Rate of Pseudorhecia of Mycosphaerella nawae, the Causal Organism of the Spotted Leaf Castin of Persimmon

감나무 둥근무늬낙엽병균(Mycosphaerella nawae)의 위자낭각 성숙에 영향을 미치는 환경요인

The environmental factors affecting maturity of pseudothecia overwintered in iufected leaves by Mycosphaserella nawae was investigated. The pseudothecia in the overwinteringinfected leaves were matured at the end of April when the average temperature was $14^{\circ}C$ and precipitation was enough. Pseudothecia initiation was preceded by the fungal biomass development in a given host. The maturity of the pseudothecia from the leaves defoliated in early October was earlier and higher than those defoliated in November of the previous year. Pseudothecia development was also positively affected by low temperature. The maturity time, as determined by percentage of matured pseudothecia out of prematured ones, was also 20 days earlier, and the rate of maturity was higher for the leaves overwintered in door, than for those kept in greenhouse. We have providedevidence that the conidia play a significant role in the epidemiology of this pathogen. Many pseudothecia were developed in the leaves infected by artificially inoculated conidia and maturation rate of the pseudothecia was not different from that of the typical symptom by ascospores infection of Mycosphaerella nawae.

감나무 둥근무늬낙엽병 이병엽에서의 이듬해 봄 위자낭락 성숙에 영향을 미치는 환경요인에 대한 검토를 하였다. 월동 후 이병엽에서 위자낭각이 완전히 성숙되는 시기는 대체로 4월 하순이었는데 이때의 평균 기온은 $14^{\circ}C$ 정도였고 충분한 강우가 있을 때였다. 낙엽시기에 따른 성숙 정도는 10월 초에 낙엽된 이병엽이 11월 초 낙엽된 이병엽보다 성숙율은 상당히 높았으나 성숙시기에는 차이가 없었다. 월동장소에 따른 차이는 야외에서 월동된 이병엽은 온실에서 보관되었다가 이듬 봄에 야외에 노출한 것보다 성숙시기가 20일 정도 빨랐고 성숙율도 훨씬 높았다. 그리고 분생포자를 인공접종하여 발병된 이병엽에서도 위자낭각이 다수 형성되었고 이듬해 봄 성숙율도 자낭포자의 자연감염에 의한 병반에서와 큰 차이가 없었다.