烟草赤星病生防菌的分离与鉴定

从连作障碍较严重的烟草根际土壤中分离出49株细菌活体纯培养物，依次编号为HHHB1～HHHB49，并筛选出对烟草赤星病病原菌（Alternaria alternate）具有拮抗活性的菌株HHHB7和HHHB19，二者抑菌圈直径分别为5、23 mm。二者初步定性为具有生防活性。多相鉴定结果表明，活性最强的菌株HHHB19隶属于假单胞菌属（Pseudomonas），暂定名Pseudomonas sp. HHHB19。盆栽试验证实，HHHB19菌株悬液叶面喷雾混合处理对烟草赤星病不同发病阶段均表现出一定的防治效果，其中喷施14 d后防治效果达61.83%。菌株HHHB19可作为良好的生防菌备用资源。

Screening and application of biocontrol bacteria for tobacco black shank disease

Using tobacco rhizosphere soil with serious continuous cropping obstacles as materials, 49 bacterial pure cultures in vivo were cultured by plate separation technology, numbered HHHB1 ~ HHHB49 in turn. The strains with antagonistic activity against tobacco Alternaria alternate were screened from the 49 strains obtained by plate antagonism experiment. A total of 2 strains with obvious antibacterial effect were screened, namely HHHB7 and HHHB19, The diameters of the three bacteriostatic circles were 5 mm and 23 mm respectively, which were preliminarily identified as strains with biocontrol activity. The results of multiphase identification of the most active strain hhhb19 showed that HHHB19 belonged to Pseudomonas sp. HHHB19; Pot experiments showed that the mixed treatment of HHHB19 suspension with foliar spray had certain effects on different stages of tobacco brown spot disease, and the control effect reached 67.83% at 14 d. Strain HHHB19 can be used as a good backup resource for biocontrol.