在陕西省紫阳县四旁栽植的香椿Toona sinensis(A. Juss.)Roem。多处发生带化病。据在该县毛坝等地区的调查961株香椿树,有带化病树50株,一般发病率约5%,严重地区发病率达20%以上,而且病害仍在发展。此病在河南信阳亦有零星分布。树木带化病又称扁枝病,感病的香椿树最显著的症状是新生的枝条呈扁平的带状,并在病枝上伴有簇生枝及小叶现象。每年3、4月间,新发病株是在4、5年生香椿树或经平茬后第3年萌发的枝条生长呈扁平枝状,尖端卷曲或扭曲向内再向上生长,如同一把大刀,老乡形象地称为春秋刀(图版Ⅰ-5)。有在病树上数个病枝条并生在一起形成铲状。连续生长几年病变枝条变细,弯曲盘结生长形成一个大疙瘩。严重影响香椿的生长和木材的利用,此病的蔓延亦阻碍丁香椿树的发展。本文报道了在香椿带化病枝的韧皮部发现类菌原体(MLO)。在高等木本植物上被类原核微生物感染,表现带化、扁枝症状的病害,尚属第一次用电镜观察到。 Toona sinensis (A. Juss.) Roem. Planted on four sides of Ziyang County, Shaanxi Province. Multiple occurs with disease. According to a survey in Mao County and other areas, 961 Toona sinensis trees have 50 endemic tree species, the general incidence rate is about 5%, and the incidence rate in severe areas is over 20%, and diseases are still developing. The disease is also scattered in Xinyang, Henan Province. Tree banding disease, also known as flat stick disease, the most prominent symptoms of susceptible toon tree is a newborn branches were flat ribbon, and in the branches with clusters of branches and leaflets phenomenon. In April and April each year, the newly infected plants grow flatly in branches of 4-5 year-old Toona sinensis or the third year after stubble. The tip of curl or twist grows inwards and upward again. Like a big knife, Fellow vividly known as the spring knife (Figure I-5). There are several diseased trees in the diseased tree and spawned together. Growing a few years continuous lesion twigs thin, curved disc knot growth to form a large lump. Seriously affecting the growth of Toon and the utilization of wood, and the spread of the disease also hindered the development of the tree. This paper reports the discovery of mycoplasma (MLO) in the phloem of Toyohashi chinensis. In higher woody plants by prokaryotic microbial infection, the performance of banding, bilobal symptoms of disease, is the first time observed by electron microscopy.