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该病从中下部叶片先发生,后逐渐向上扩展。重病株除心叶外,均可染病。病斑近圆形或不规则形,黄褐色,潮湿时着生黑色霉层。叶背病斑呈水渍状。病斑上具同心轮纹,边缘明显且具褪绿晕圈。病斑多生于脉间,数个病斑连片后整叶呈黑焦枯状,但不脱落。病原菌以菌丝体或分生孢子在病株残体上、或粘附在种皮表面越冬,借雨水或气流传播。高温高湿条件下该病易流行。
The disease occurs first in the middle and lower leaves and gradually increases upward. In addition to heart sick leaves, can be infected. Nearly circular or irregular lesion-shaped, brown, moist black mold layer. Leaf spot is water stains. Lesions concentric heart pattern, obvious edge and faded green halo. Lesions were born in the meridians, several lesions contiguous dark brown coke-like, but not fall off. Pathogens to mycelium or conidia in the diseased plant residues, or the surface of the seed coat overwinter, by rain or air flow. The disease is prevalent under hot and humid conditions.