Studies on the Disease of Pear Rust caused by Gymnosporangium haraeanum SYDOW I. Some Ecological Investigation of Inoculum Source
배나무 붉은별무늬병은 1973년이래 해마다 발병이 증가하여 1975연에는 발병엽율 에 달하였으며 1974년 향나무 재식규제조치이후 감소하였다. 붉은별무늬병원균의 동포자발아 시기는 4월중순부터 5월중순까지 였으며 인공강우에 의하여 그 발아시기를 5일 전에 알 수 있었다. 성숙한 동포자퇴의 포자발아에는 3시간 이상의 계속되는 비로서 상당량의 강수가 필요하였다. 배나무의 감염은 강우중이나 강우직후에 이루워지고 있었으며 강양 24시간 이후의 감염은 없었다. 감염후 배나무에서의 잠복기간은 일이었다. 배나무와 향나무사이의 지리가 100m 이내인 경우에는 거의 모든 배나무가 발병하였으나 거리가 멀어짐에 따라 발병율도 감소하였으며 2km 이상에서는 발병이 없었다.
The outbreak of the pear rust caused by Gymnosporangium haraenum SYDOW has increased gradually since 1973, and amounted to 60.3 percent infection of leaves in 1975. But it has reduced due to regulation of juniper plantings by Plant Protection Law enacted in 1974. The teliospores of C. haraeanum germinated from middle of April to middle of May under natural condition. The germination of teliospores was observed 5 day earlier under laboratory condition with the artificial rainfall than that of natural condition. It was required considerable rainfall and longer than 3hr rainy period to germinate teliospores after being matured. Infection of rear leaves took place in the rain or just after the rain, but not after 24hr. The incubation period of G. haraeanum on the leaf was 9 to 10 days. In case that the distance between orchard and juniper trees was less than loom, almost all of the pears were infected, but the chance oft infection reduced in proportion as the distance increased. No infection occurred at the distance of further than 2000m.