油桐带化病中发现的类细菌（BLO）

油桐(Aleurites fordii Hemsl.)是陕西省紫阳县重要的经济林树种之一,但在该县发现油桐感染带化病严重,病害呈点片状发生,根据在洞河、城关等地区调查,一般发病率为3％,严重的达7％,发病的油桐树龄为2—5年,以3年生幼树发病较严重。油桐带化病病变形态与香椿带化病病变十分相似。感病的油桐树在未发生病变的前一年,树高有生长迅速的特点,一般在病枝以下的一节(于两侧枝之间)一年内高生长达3—4m。病树最显著的病状是新生的枝条呈扁平的带状,尖端卷曲或扭曲生长,如同一把大刀,有的形成齐头铲状,最宽处可达13cm,病枝叶片明显变小(图5);当枝梢孕育花芽亦能开花座果,果实仅有正常成熟果实大小的1/4,萎缩枯死,影响油桐树的正常生长及桐油产量。此病的蔓延阻碍了油桐树的发展。

A NEW FASCIATED DISEASE OF ALEURITES FORDII ASSOCIATED WITH BACTERIA-LIKE ORGANISMS

The fascited disease of Tungoil tree (Aleurites fordii Hemsl.) was found in Ziyang county of Shanxi Province, China. The result of the electron microscopy study showed that the Bacteria-like organisms (BLO) were present in the sieve elements of the phloem as well as in some parenchyma cells of the diseased plants, but not in those of the healthy ones.