论文部分内容阅读
大葱紫斑病在我省发生面积广,危害严重,它与锈病和霜霉病被称为大葱的三大病害。大葱紫斑病多在生育中后期为害叶片和花梗。病斑多从叶尖或花梗中部开始发生,几天后可蔓延至下部。初时病斑很小,稍凹陷,淡褐色,中央微呈紫色。病斑扩展后成椭圆形或纺锤形,呈紫色或紫褐色。湿度大时病斑上长满紫黑色霉层,常排列成同心轮纹状。条件适宜时,病斑继续扩展,数个病斑连成长条状大斑,致使叶片或花梗枯死。当病斑绕叶片或花梗一周时,则叶片或花梗多从病部软化倒折。严重时植株叶片全部枯死,减产极重。
Purple onion disease occurs in our province a wide area, endangering serious, it is rust and downy mildew is known as the three major diseases of green onions. Purple onion disease mostly in the late reproductive damage leaves and pedicel. Lesions and more from the tip of the middle of the pedunculate or pedunculate, a few days later spread to the lower part. Early lesions are small, slightly depressed, light brown, central slightly purple. Lesions spread into an oval or spindle-shaped, purple or purple-brown. When the humidity is high, the lesion covered with purple black moldy layer, often arranged in concentric rings. When the conditions are right, the lesion continues to expand, even with a few large lesions strip big spot, resulting in dead leaves or peduncles. When the lesion around the leaves or pedicel a week, then the leaves or pedicel more softening from the disease refolding. In severe cases, all the leaves of plants withered, cut extremely heavy.