白粉病:主要为害叶片,发病初期在叶面或叶背及幼茎上产生近圆形小粉斑,叶正面多,以后向四周扩展成边缘不明晰的连片白粉,严重的整个叶片布满白粉。发病后期,白色的菌斑上生出成堆的黄褐色小粒点,后小粒点变黑。防治方法:合理施肥,增施磷钾肥,提高植株抗病能力。禁止大水漫灌,谨防棚室干湿交替造成严重发病。注意田间通风透光,保持田间清洁,及时摘除病叶、老叶。发病初期喷施40%多·硫悬浮剂800 Powdery mildew: the main damage leaves, the early onset of foliar or leaf dorsal and young stems produce nearly round small speckles, the front of the leaves more, later extended to the surrounding edge of the unclear contiguous white powder, severe whole leaf full White powder. Late onset, the white plaque generated piles of brown small particles, after the small particles black. Control methods: rational fertilization, increase phosphorus and potassium, improve plant disease resistance. Prohibit flood irrigation, beware of dry and wet alternately lead to serious disease. Pay attention to the field ventilation and light, keep the field clean, timely removal diseased leaves, old leaves. Early onset of spraying more than 40% sulfur suspension agent 800