一、病害症状(一)丝瓜霜霉病主要为害叶片,病叶先出现不规则淡黄色至鲜黄色病斑,后扩大为多角形黄褐色病斑,潮湿时病斑背面出现紫黑色霉层,后期病斑连成片,叶片枯死,严重减产。该病病原为古巴假霜霉真菌,病菌在病残体上越冬。低温阴雨,空气湿度大,昼夜温差大,田间排水不良,均有 First, the symptoms of disease (a) gourd downy mildew is the main damage leaves, diseased leaves appear irregular yellowish to yellowish lesions first, then expanded to polygonal brown spots, damp spots on the back of purple black mold layer, After the film even into pieces, dead leaves, a serious cut. The disease pathogen is Cuba Fungal fungi, winter in the disabled disease. Low temperature and rainy, air humidity, temperature difference between day and night, the field of poor drainage, both