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1.白粉病危害症状:叶正反面产生白色小斑点,逐渐扩大,后来连成片,布满白色霉层,霉斑边缘不整齐,后成灰白色,有时病斑产生许多小黑点,叶片逐渐变黄,发脆,干枯而不落。发病条
1 powdery mildew hazard symptoms: small white spots positive and negative leaves, and gradually expanded, and then even into a film, covered with white mold layer, mildew edge irregular, then into an off-white, and sometimes lesions have many small black spots, leaves gradually Yellow, crisp, dry and not fall. Disease incidence