一、莴苣黄萎病莴苣黄萎病由类菌质体引起,由叶蝉类昆虫于苗床或本田初期传播,一般在定植后不久就发病,病株叶色变淡,心叶呈米黄色,幼苗期感染多出现顶端自枯症状,新芽生长完全停止,下叶黄化,出现米黄色坏死斑并迅速枯死。大苗染病多出现丛生症状,由顶芽腋芽长出很多丛生细叶。预防该病主要应防治叶蝉,可喷施2.5%功 First, lettuce Verticillium lettuce Verticillium wilt caused by the like bacteria, by the leafhopper insects in the seedbed or Honda early spread, usually in the colonization soon after the onset of diseased leaves pale, the heart leaves were beige, Seedlings infected with apical symptoms of autopsy, sprout growth completely stopped, under the yellow leaves, appear beige necrotic spots and died quickly. Larger disease appears more clusters of symptoms, buds axillary buds grow a lot of clusters of fine leaf. Prevention of the disease should mainly prevent leafhoppers, can spray 2.5% of work