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目前,我国种植面积最大的蔬菜为大白菜,是主要的冬季蔬菜,但是病害对其产量影响很大,为保证大白菜的产量,需及时有效防治大白菜病害,并确保生产出优质的无公害大白菜。一、大白菜霜霉病1、典型症状大白菜霜霉病的病原为寄生霜霉菌,整个生育期均易发病。下部叶背出现水渍状淡黄色周缘不明显的病斑,一段时间后叶背出现白色霜霉,正面出现黄色病斑渐变为黄褐色。严重时病斑连片,病叶枯死。2、防治措施
At present, the vegetable with the largest planting area in our country is Chinese cabbage, which is the main winter vegetable, but the disease has a great influence on its yield. In order to ensure the yield of Chinese cabbage, it is necessary to effectively control the disease of Chinese cabbage and ensure the production of high quality and pollution-free Chinese cabbage. First, Chinese cabbage downy mildew 1, the typical symptoms Cabbage downy mildew parasitic disease caused by parasites, the entire growing period are susceptible to disease. The lower part of the leaves appeared water stains pale yellow peripheral lesions are not obvious, after a period of time the leaves back white downy mildew, positive yellow lesions appear yellow to brown. Serious lesions of contiguous, sick leaves withered. 2, prevention and control measures