黄瓜黑星病已在兰州发生１９９３年以来，兰州市的个别地区日光温室中种植的黄瓜发生了一种病害，轻则减产５０％～７０％，重则全棚绝收。病害症状：幼苗期子叶上产生黄白色圆斑，严重时小叶枯萎，全株死亡；成株期叶片上病斑淡黄褐色，后期中部开裂为不规则星状孔，病部... Cucumber scab has occurred in Lanzhou since 1993, Lanzhou City, in some areas of greenhouse cucumber grown in a disease, ranging from cut 50% to 70%, while the whole shed is absolutely closed. Symptoms of disease: yellow-white spots on the cotyledons at seedling stage, withered leaflets in severe cases, death of the whole plant; light yellowish-brown spots on leaves of adult plants;