前言为了避免新病害引入未感染地区的危险,脱毒植株的生产是国际间交换无性系材料的先决条件。Scheafers 和 Terry 描述过尼日利亚(Nigeria)的甘薯脉明病(1976),他们断定这种病是由两种病原体复合侵染引起的。第一种是由桃蚜和棉蚜传播的非持久性病毒(病毒粒子丝状,长达850毫微米)。它单独在甘薯中呈潜隐状态,但在巴西牵牛(I.setosa)上能 Introduction To avoid the danger of new diseases being introduced into uninfected areas, the production of virus-free plants is a prerequisite for international exchange of clonal material. Scheafers and Terry described the sweet potato disease in Nigeria (1976), who concluded that the disease was caused by a combination of two pathogens. The first is a non-persistent virus (viroid filamentous, up to 850 nm) transmitted by green peach aphids and cotton aphids. It is solitary in the sweet potato but can be found on I.setosa in Brazil