Biocontrol Of Strawberry Replant Disease By Antagonistic Microorganisms

Strawberry replant disease was one of the problems threatening strawberryproduction. This reaserch tried to screen effective antagonistic microorganisms from soilsamples that were collected from different rhizosphere. The aim was to provide a newclue for controlling strawberry replant disease effectively.1. The biological characteristics of Pestalotiopsis photiniae were studied. Theresults showed that the favorable condition for mycelia growth was 25℃, pH5, glucoseas carbon source and carbamide as nitrogen source. The optimal condition for conidiagermination was 25℃, pH6, maltose as carbon source or carbamide as nitrogen source.2. Four hundred and forty eight isolates with differently morphological colony wereisolated from 50 soil samples collected from 20 different fields. 1 strain of fungal, 26strains of actinomycoces and 253 strains of bacteria were got after confrontation trainingselection. The most effective antagonistic microorganism to each of the 4 pathogens wasas follows. The inhibition zone of JP50 against R. solani, JP61 against F. oxysporum,JP130 against V. dahliae and JKX84 against P. photiniae was 20.33 mm, 20.00 mm,18.50 mm and 13.67 mm, respectively. Research showed that: the microorganisms fromstrawberry replant disease fields at florescence had obviously efficiency. Strains JKX78,JKX83,JKX84,JP132 had broad-spectrum antifungal activity on Rhizoctonia solani,Fusarium oxysporum, Verticillium dahliae and Pestalotiopsis photiniae. Afteridentification they were considered to be Bacillus subtilis.3. The 4 strains of Bacillus subtilis were fermentated. The inhibition of the mixturesand the singleness fermentation were tested on the mycelium growth and conidiumgermination of 4 kinds pathogens. The most efficiency inhibition to mycelium growthwas KX78+83 against R. solani and F. oxysporum, JKX78+JP132 against P. photiniaeand JKX83+84 against V. dahliae, the inhibition rates were 84.40% and 78.90%, 79.90%and 84.10%. Inhibition rate of conidia germination JKX78+83 against F. oxysporum andV. dahlia, JKX83+JP132 against P. photiniae, was 91.00% and 79.00%, 83.00%. Theeffect of JKX83+84,JKX78+83 against the mycelium of R. solani,F. oxysporum,V.dahliae,P. photiniae were good, The effect of JKX78+83 and JKX83+JP132 against the conidia of F. oxysporum,V. dahliae,P. photiniae were good.4. The optimum fermentation condition of isolate JKX78, JKX83, JKX84 and JP132were screened. The isolate JKX78 was cultured in liquid media GB, pH9.5, 25℃, 24h.The isolate JKX83 was cultured in media SY, pH6.5, 25℃, 24h. The isolate JKX84 wascultured in media PD, pH8.5, 25℃, 24h. The isolate JP132 was cultured in media GY,pH9.5, 20℃, 24h.5. The control effect in vivo showed that the mixture JKX83+JP132, JKX78+JP132and JKX83+84 had excellent effect. The control efficiency was more than 60%.