Morphology,biological characteristics and fungicide screening of the pathogen causing pricklyash leaf mold

The prickly-ash leaf mold was a kind of disease causing prickly-ash defoliation,which occurred recently in Shaanxi Province and the pathogen was identified as Pseudocercospora zanthoxyli( Cooke)Guo Liu. The tests on the biological characteristics of P. zanthoxyli showed that the growth of the pathogenic fungus was best in PPDA medium and that in the PDA medium was the next,mannose was the best carbon source and peptone was the appropriate nitrogen source; the optimum temperature for pathogen growth was 25 ℃,The pathogen colonies favored growth condition with a little acid( pH 5 ~6) and illumination had little effect on its growth. Fungicide screening test proved that the inhibiting effect of tebuconazole was the best with the EC50 vaule of 0. 0471 mg /L,followed by that of mancozeb and thiophanate methyl with the EC50 vaules of 3. 064 mg /L and 4. 414 mg /L,respectively.