华东地区油菜和十字花科蔬菜花叶病的初步研究

 南京及华东地区的油菜与十字花科蔬菜普遍发生花叶病。病原病毒經抗性(失毒温度、稀释終点、体外保毒期)測定和寄主反应測定,认为可以分作三大类型:分别为芸苔病毒2号,黄瓜病毒1号与烟病毒1号的株系。前两种病毒都能为害油菜、大白菜、白菜、芥菜、蘿卜等,但不为害甘蓝型的蔬菜,并都能引起菠菜和茼蒿的花叶,和在烟上引起局部枯斑。第一型在烟农特400号和心叶烟上不引起花叶,而第二型在烟和心叶烟上都能引起系統性花叶。第一型不为害心叶烟,而第三型可在心叶烟上引起小枯斑。第一型与凌立、楊演的油菜花叶病毒相近似,而和范怀忠、柯冲从十字花科蔬菜中所分离出的分离物1号最为相象。与裘維蕃、王祁楷在白菜上所发現的孤丁病毒的差别,在于不能侵害甘蓝类的蔬菜。第二型病毒与范怀忠、柯冲的分离物3号相近似,但与典型的黃瓜花叶病毒仍具有一定的差异。这些病毒在油菜上所引起的症状却沒有明显的差別。

MOSAIC DISEASE OF CHINESE RAPE AND OTHER CRUCIFERS IN EASTERN CHINA

Chinese rape, varieties of Brassica campestris and B. chinensis and many cruciferous crops including radishes, but except varieties of B. oleracea, are generally affected by a mosaic disease, causing serious losses amounting occasionally to a death rate of over 90%, while an infection rate of over 30% is not uncommon. The symptoms involved were vein-clearing, yellow or green vein-banding, typical mosaic, rugosity of leaf lamina, dwarfing and rosetting. They may appear in different combinations. Flower stalks may not come out or are shortened, deformed and twisted. Flowers appeared pale yellow and become abortive, or forming only small and twisted seed pod, which are sometimes spotted with black necrosis, and bearing small and deformed seeds. When the winter temperature is low, diseased plants may succumb first, forming missing hills. Late infections may result only in vein-banding of the upper leaves and partial abortion of the seeds. On several varieties of radish, mostly of the green type, which apparently are more resistant, only fine mottling appears on the leaves while infected. On varieties of B. napella, another oil-bearing group, the symptoms are entirely different (plate 1, fig. 5), appearing as systemic bright yellow spots on the leaves. Necrotic flecking can eventually be found at the center of these spots. Necrotic streaks and spots develop on the flower stalks and seed pods. Dwarfing and distortion occur on leaves, stalks and pods, and death may even be resulted from severe infections. However, this species showed certain degree of resistance to the disease in the form of late infection and the lower incidence of the disease.