一、分布与危害腐烂病是生菜(散叶莴苣、结球莴苣)主要的病害之一,各地都有分布发生。一般在生菜生长中后期开始发病,造成腐烂。以露地栽培受害最重、产量损失可达80%。北京棚室生产一般发病率3%～10%,严重者30%以上。二、症状识别该病多从植株基部叶柄或根茎丌始侵染。初呈水浸状黄褐色斑,逐渐由叶柄向叶面扩散,或从外叶叶缘形成灰白至浅褐色较大病斑,向叶球里层发展,最 First, the distribution and damage Rotten disease is lettuce (lettuce, ball lettuce) one of the major diseases, all over the distribution. Generally in the late lettuce growth onset, resulting in decay. In the open field cultivation hardest hit, yield loss up to 80%. Beijing studio general incidence of 3% to 10%, in serious cases more than 30%. Second, the symptoms of the disease mostly from the base of petioles or rhizomes plant infiltration. At the beginning of the water-soaked brown spots, gradually from the petiole to the leaf surface diffusion, or from the outer edge of the leaves to form a gray to light brown larger lesion, to the leaf layer development, the most