病种薯是马铃薯晚疫病主要的初侵染来源，中心病株的出现是发生的重要标志，6～8月份的降雨是流行的关键因素。
Diseased seed potato is the major preliminary infection source , the appearance of center disease plant is an important sign of occurrence , and the rainfall from June to August is a key factor of epidemics .
中心病株