The inhibitory effects of 10 fungicides on apple tree valsa canker were compared on dishes and twigs.The results showed that conidia germination and mycelial growth were inhibited by all fungicedes tested.The EC50 value of Difenoconazole was 6.1×10-3 μg·mL-1,the lowest among tested fungicide in inhi-biting conidia germination.Tebuconazole and Imazalil also showed obvious inhibition effect.Thiophanate-methyl was the least efficient with the EC50 value 2.6×101 μg·mL-1.Difenoconazole also showed the highest activity for inhibiting mycelial growth with EC50 value of2.3×10-2 μg·mL-1.Tebuconazole was better than other fungicide.Thiophanate-methyl and Propineb were the least efficient with quite high EC50 value.Furthermore,the size of the lesion after inoculation on excised twigs also revealed that Difenoconazole was most efficient because it showed the smallest lesion of 394 mm2 compared with other tested fungicides.So Difenoconazole and Tebuconazole could be used to control apple tree valsa canker in field to subsititute forbided fungicides such as asomate.
[ 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
