Study On Biocontrol Bacteria Against Citrus Canker

Bacterial strains Ab8, BvlO, Bp27, Bc51 were biocontrol agents isolated from soil, exteriors of leaves and inside of leaves in citrus orchard of Qingxiu Hill Park and Hepu in Guangxi Nanning. These strains were classified into the genus of Acinetobacter, Bacillus, Brevibacillus, Burkhholderia by analyzing their 16SrDNA sequences. Further detection of physiological and biochemical characteristics revealed that these strains belonged to Acinetobacter baumannii Bouvet et Grimont, Bacillus validus (Ehren-berg) Cohn 1872, 174 vp., Brevibacillus parabrevis (Takagi et al 1993) Shida et al 1996 , Burkhholderia cepacia Yabuuchi et al, respectively. Their fungistatic actions were influenced by temperatures, pHs and media. In greenhouse test, strain Ab8, BvlO, Bp27, Bc51 showed 52.6%, 42.90%, 36.6%, 60.30% of lesion inhibition rate against citrus canker, respectively. The bioassay results of genetic stability in the inhibition activity of Ab8, BvlO,Bp27, Bc51 indicated that these strains had stable antagonistic activities against X.citri, During 8 generations transferred, the diameters of inhibition zone scarcely varied. BvlO, Bp27 and Bc51 strains had extensive inhibition spectrum, inhibition rate of Bv10 against Botryis cinerea and Phomopsis obscurans arrived at 100%.