云南省烟草青枯病的侵染动态

为了指导烟草青枯病的测报和防治，采用定期挖根调查采样和ELISA检测方法，对云南省烟草青枯病的侵染动态进行了研究。移栽后每周挖根调查结果和根、茎部样品的检测结果表明，在文山州青枯病重病田块，移栽后第5周根部样品首先检测出青枯雷尔氏菌（Ralstonia solanacearum，简称青枯菌）阳性，个别烟株根部出现黑色坏死症状；移栽后第7周根部样品青枯菌检出率达到50%左右、根部黑色坏死发病率开始快速上升，茎部无明显症状；移栽后第9周，根部发病率达到50%左右、个别烟株茎部出现黑色坏死症状。移栽后第12周，茎部青枯菌检出率、根发病率和茎部发病率均达到80%以上。根部样品青枯菌检出阳性、烟株根部显症、烟株茎部显症表现出一定的时间顺序（先后间隔约21d）。根青枯菌检出阳性时期和根黑色坏死的始发期可作为确定第一次施药时期的依据。对ELISA检测的验证试验结果表明，ELISA检测为青枯菌阳性的样品，可分离到典型青枯菌菌落，分离物ELISA检测同样为青枯菌阳性。

The Dynamics of Tobacco Bacterial Wilt in Yunnan Province

In order to direct tobacco bacterial wilt disease control and forecast,the dynamic of tobacco bacterial wilt in Yunnan province were carried out through period field roots survey and ELISA test.In the high disease incidence field in Wenshan prefecture,roots samples detect Ralstonia solanacearum positive firstly at five weeks after transplant(w.a.t),and only several tobacco plant roots show black necrosis.At 7 w.a.t,50% roots samples detect R.solanacearum positive,roots black necrosis plant incidence increase rapidly,while stem show no obvious symptom.At 9 w.a.t,50% roots samples detect R.solanacearum positive,roots black necrosis plant incidence up to 50%,while several plant show stem black necrosis;At 12 w.a.t,stems R.solanacearum positive percentage,black necrosis roots incidence and black necrosis stems incidence up to 80%.The period of roots samples with high R.solanacearum positive,roots displaying symptom and stem displaying symptom occurs successively at certain interval(about 21 days).Root samples with R.solanacearum positive time and roots black necrotic emerge time could server as a basis of decision of first chemical applying period.The confirmation result of ELISA test show that R.solanacearum type colony could isolated form the ELISA test positive samples,and the type culture also show R.solanacearum positive when tested by ELISA.