Study on biological characteristics of cyclamen leaf spot

Leaf spot (Alternaria alternate) was a kind of newly occurred leaf disease of cyclamen in Gansu Province in recent years. The pathogen was identified as Alternaria alternate (Fr.)Keissler according to its morphology, culture character and pathogenicity after isolated and cultured. The results showed that the pathogen could grow at the temperature from 10 ℃ to 35 ℃ , the optimum temperature was from 25 ℃ to 30 ℃ ,when the temperatucre was lower than 5 ℃ or higher than 35 ℃ ,it couldn't grow. The suitabe pH value for its growth was from 4 to 9 ,the optimum pH was 6. The lethal temperature was 55 ℃ for 10 min,the conidia could geminate under the condition of temperature from 10 ℃ to 40 ℃ ,RH from 81 % to 100 % ,and pH value from 4 to 9. The germination rate was the highest at 25 ℃ ,pH value 6 and the RH 90 %.