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霜霉病是甜菜的危险病害,发生时严重降低产量及含糖量,此病在欧美均有发生,但在我国过去尚无报导。1961年在贵州进行甜菜病虫害基本调查时,在毕节专署农科所、毕节县城关公社和平大队、遵义农校(一年生及二年生留种株)甜菜地均发现感染有霜霉病。部分田块发病率为20—40％。初步进行了症状、病原和发病条件的观察。此病在一年生甜菜上,一般从心叶开始发病,受病部位退成浅绿色或淡黄色,病斑形状不规则,边缘模糊,病害进一步发展时,叶片边缘
Downy mildew is a dangerous disease of sugar beet, which seriously reduces the yield and the sugar content when it occurs. The disease has occurred in both Europe and the United States, but it has not been reported in our country in the past. In 1961, a basic survey of beet diseases and insect pests in Guizhou was carried out. Downy mildew was found in beetroots of the Agricultural Science Institute of Bijie Agency, the Peace Corps of Chengguan Commune in Bijie County, and the Zunyi Agricultural School (annual and biennial species). The incidence of some fields is 20-40%. The initial symptoms, pathogens and incidence of conditions observed. The disease in the annual beet, the general onset from the heart leaves, the affected part retreat into light green or yellow, spot irregular shape, fuzzy edge, the disease further development, the edge of the leaves