一、病害症状马铃薯植株叶、叶柄、茎及块茎均能发生晚疫病。叶片发病初期,叶尖或叶缘出现暗绿色水渍状斑点,天气潮湿时,病斑迅速扩大,叶背病斑边缘长出一圈白色霉层。严重时病斑扩展到主脉和叶柄,气候干燥时,病斑干枯变褐。茎部受害,初呈稍凹陷的条斑,气候潮湿时,表面产生白色霉层。块茎发病时,形成淡褐色或灰紫色不规则形病斑,稍下陷,薯肉变褐。土壤干燥时,病部发硬,潮湿时长出白霉。二、发病条件马铃薯晚疫病的发生与流行和气候条件有直接关系。发病条件一旦 First, the symptoms of disease Potato plant leaves, petiole, stems and tubers can occur late blight. The early onset of leaves, leaf tips or leaves edge dark green water-like spots, the weather is humid, the rapid expansion of lesions, leaves back edge of a white mold layer grow mildew edge. Severe lesions extended to the main vein and petiole, dry climate, spots dry brown. Stem damage, the beginning of a slightly concave bar streak, the climate is humid, the surface white mold layer. Tuber disease, the formation of light brown or purple irregular spots, slightly sag, brown flesh. When the soil is dry, the diseased part grows hard and grows white mold when wet. Second, the incidence of conditions The occurrence of late blight potato and epidemic and climate conditions are directly related. Once the conditions of onset