Investigation of Kiwifruit Bacterial Canker Disease(Pseudomonas syringae pv.Actinidiae Takikawa) in Guanzhong Area of Shanxi Province and Its Biological Control

[ Objective ] The paper was to grasp the incidence characteristic of kiwifruit bacterial canker disease （Pseudomonas syrirtgate pv. actinidiae Takikawa） in Guanzhong area of Shanxi province, and to screen the endophytic actinomycetes with control effect against kiwifruit bacterial canker. [ Method] The incidence characteristics of kiwifruit bacterial canker disease in 65 orchards of 13 villages in guanzhong area of Shanxi province （Yangling, Zhouzhi, Meixian） were investiga- ted and analyzed. The antagonistic strains against Pseudomonas syringae were simultaneously screened from 242 endophytic actinomycetes, and carried out field dis- ease control test. [ Result] The average incidence rate of kiwifruit bacterial canker disease in guan^ong area of Shanxi province was 7.95% ; the variety of kiwifruit had dose relationship with incidence rate. 76 strains bad inhibition activity agmnst P. syringae, while the inhibition zone diameters of fermentation broths of 35 strains against P. syr/ngae were greater than 20 nun. TIASA5 strain had inhibition activity against four target bacteria; gCLA4 strain not only had inhibition activity against four target bacteria, but also had strong inhibition activity against 10 species of plant pathogenic fungi. Field test showed that the fermentation broth of gCLA4 strain had obvious control effect against kiwifruit bacterial canker disease, and the relative control effect at 21 d could reach 66.7%. [ Conclusion] The an- tibacterial spectrum of fermentation broth of gCLA4 strain is broad, so gCLA4 strain has the potential to be developed into a broad-spectrum agricultural fungicide. Key words Kiwifruit bacterial canker disease; Endophytic actinomycetes; Biological control; Field test

Control Efficacy of Streptomyces sp. SY-L12 and Chitooligosaccharide on Kiwifruit Bacterial Canker, Pseudomonas syringae pv. actinidiae

[ Objective] The paper was to develop a priority scheme for prevention and control of kiwifruit bacterial canker with biological agents. [ Method ] The inhibitory effect of Streptomyces sp. SY-L12 on the growth of Pseudomonas syringae pv. actinidiae were assessed using liquid co-culture and inhibition zone meth- ods. The control efficiency of Streptomyces sp. fermentation broth against kiwifruit bacterial canker was studied via potted trial. [ Result ] As Streptomyces sp. SY- L12 was incubated for 24 h, the growth inhibition rate of its fermentation broth on P. syr/ngae pv. actinidiae was 94.0%. The control efficiency of fermentation broth against P. syringae pv. actinidiae was the best of 85.4% in potted trial when Streptomyces sp. SY-L12 grew at 28~C, 150 rpm for 8 -9 d, better than that of control agent copper hydroxide. The control efficiency was improved as the agent was mixed with 1 mg/L chitooligosaccharide. [ Conclusion] Streptomyces sp. SY-L12 could effectively inhibit the growth of P. syr/ngae pv. actinidiae, and can be developed as biological agent against kiwifruit bacterial canker.