白粉病是新疆甜菜的主要病害,一般发病率50％～90％,严重者高达100％,病情指数20～90。发病植株,轻者叶片出现病斑,光合作用不能正常进行,重者则生长缓慢,功能叶片枯萎、脱落。发病甜菜一般减产10％～20％。块根糖度下降0.5～1.2度,给甜菜生产和制糖工业带来重大损失。 1 主要病症 甜菜白粉病主要危害甜菜叶片、叶柄。在石河子地区7月中、下旬,发病植株首先在叶片上出现直径约1cm的绒毛状病斑,病斑从下层叶片开始发生,逐渐感染上部叶片,而且病斑从叶片基部向上扩展, Powdery mildew is the main disease of beet in Xinjiang, the general incidence of 50% to 90%, severe up to 100%, the disease index 20 to 90. Diseased plants, light leaves appear lesions, photosynthesis can not be normal, heavy growth is slow, functional leaves withered, fall off. Diseases beet generally cut 10% to 20%. The sugar content in root tuber drops 0.5-1.2 degrees, which brings great losses to beet production and sugar industry. 1 main diseases beet powdery mildew main harm beet leaf, petiole. In Shihezi region in mid-July and late July, the diseased plants first appeared villous lesions with a diameter of about 1 cm on the leaves. The lesion began to occur from the lower leaves gradually infected with the upper leaves, and the lesion extended upward from the base of the leaves.