Screening of fungicides against the pathogen causing brown spot of Ziziphus jujuba Mill.cv. Hu-pingzao

Brown spot of Hupingzao was a serious fruit disease in Shanxi Province.The typical symptom was the brownish spots occurred on the top or shoulder parts of jujube fruits.The pathogen of this disease was identified as Alternaria alternata(Fries) Keissler with karyokinesis spores.The in vitro inhibition of mycelium growth and spore germination caused by 9 fungicides against pathogen was tested by means of mycelium growth rate method and hang drop method.The results indicated that Mancozeb,Iprodion,Carbendazim,Jianban and Propiconazole could significantly inhibit mycelium growth with the inhibition rates over 90% and Tanzujue,Mancozeb,Carbendazim,Jianban and Propiconazole could greatly depress spore germination with inhibition rates over 90% as well.Results of toxicity test showed that EC50 of Propiconazole,Carbendazim,Jianban and Mancozeb was 14.45,20.83,28.47 and 149.93 mg/L respectively and Propiconazole was the best.The correlation coefficients of four fungicides were all above 0.93,indicating a highly positive correlation between fungicide concentration and its inhibition ability.