| Potato common scab is an important economical disease caused by plant-pathogenic Streptomyces spp. It has taken place in most potato planting areas and has become a main disease in potato production in China now. It is urgent necessary to find some effective methods to control potato common scab. On the bases of four different potato scab pathogens we collected from potato growth areas in previous works, antibacterial factors against different potato scab pathogens were screened in this paper. An antagonistic strain ZWQ-1 which we obtained before was identified, and the synergistic effect between the antagonistic strain and chemicals also be studied in this work.The characteristics of morphological feature, physiology, biochemistry tests and the 16S ribosomal DNA （rDNA） sequences were used to classify the antagonistic strain ZWQ-1. The results indicated that it was positive of gram, rhabditiform germ and utilized glucose, sucrose, mannitol, fructose as carbon source, it could reduce nitrate, hydrolysis starch and gelatin. Hydrogen peroxidase and V-P reaction are positive, but pitrate is unavailability. The 16S rDNA sequence （1610 bp） of ZWQ-1 was similar to Bacillus subtilis JQ398853（99%）、JN399219（99%） according to the phylogenetic tree analysis. All of the test results showed that the strain ZWQ-1 should belong to B. subtilis. In addition the strain ZWQ-1 has the inhibition to all four different potato scab pathogens in plates （the inhibitory diameter ranged from 6.59 to 18.75 mm）, it also showed inhibition to other pathogens, such as Cephalothecium roseum, Botrytis cinerea and Verticillium dahliae, all of the inhibitory diameters were over 20.00 mm. So the strain ZWQ-1 is a potential sounce on biocontrol plant disease.Forty-seven kinds of bactericides were screened using paper plate method in this work, the results showed that 72% agricultural streptomycin, 90% xinzhimycin, gentamycin sulfate and neomycin sulfate have better inhibition effect to all of four different potato scab pathogens. For S. scabies CPS-1 pathogen, agricultural streptomycin(959μg·mL-1) was the best, inhibitory diameter is 22.23 mm. For S. galilaeus CPS-2, Xinzhimycin and agricultural streptomycin were better, the inhibitory diameter were 30.48 mm and 30.42 mm. For S. acidiscabies CPS-3, Gentamycin sulfate was the best, the diameter of inhibition was 30.93 mm. For S. turgidiscabies SHXHZ-3, Agricultural streptomycin, gentamycin sulfate and xinzhimycin were better, the diameter of inhibition zone were 37.56 mm, 35.26 mm and 31.83 mm. With the Synergistic Effect of strain ZWQ-1 of the bactericide was screened using paper plate method. The results show that 500μg·mL-1 for lincomycin hydrochloride, 668μg·mL-1 for moroxydine hydrochloride with copper acetate and other six bactericides were no influence to strains ZWQ-1. Those can be used together with antagonistic strain ZWQ-1 for further disease control.The results of pot bioassay in greenhouse indicated that the strain ZWQ-1 had better control efficiency（range from 49.68% to 79.09%）to four different potato scab pathogens. The control efficiency were 85.01% and 80.00% with 800μg·mL-1 for neomycin sulfate and 500μg·mL-1 for lincomycin hydrochloride to CPS-1. The control efficiency was 80.96% with 500μg·mL-1 for neomycin sulfate to CPS-2. The control effects were 88.11% and 81.89% with 959μg·mL-1 for agricultural streptomycin and 800μg·mL-1 for gentamycin sulfate to CPS-3. The control efficiency were 72.46% and 72.02% with 800μg·mL-1 for gentamycin sulfate and 1200μg·mL-1 for cymoxanil to SHXHZ-3. Together with antagonistic strain ZWQ-1, 668μg·mL-1 moroxydine hydrochloride with copper acetate have 94.01% and 88.47% control efficiency to CPS-1 and CPS-3 respectively, 500μg·mL-1 lincomycin hydrochloride had 90.48% control efficiency to CPS-2. |
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