腐烂病是生菜最重要的病害，各地都有发生。一般在生菜中后期或结球期开始发病，造成腐烂，使产量损失８０％以上。一、发病症状多从植株基部叶柄或根茎开始侵染。初呈水浸状黄褐色斑，逐渐由叶柄向叶面扩展，由根茎或基部叶柄向上发展蔓延，或从外叶叶缘形成灰白至浅褐色... Rotten disease is the most important disease of lettuce, all over it. Usually in the late lettuce or the beginning of the onset of disease, resulting in decay, so that more than 80% loss of production. First, the incidence of symptoms and more from the base of the petiole or rhizome infection. The initial was yellowish brown spots, gradually by the petiole to the leaf surface expansion, from the rhizome or base petiole upward development and spread, or from the outer edge of the leaves to form gray to light brown ...