Detection and quantification of Mycosphaerella nawae in persimmon using real-time PCR assay

Circular leaf spot, caused by Mycosphaerella nawae, is one of the most destructive diseases in persimmon orchards in Japan, Spain and particularly in Korea. In this study, we analyzed primary infection period and quantitative mass of scattering ascospore of M. nawae using developed real-time polymerase chain reaction (RT-PCR) and nested PCR assay. Concentration of scattered ascospore and primary infection period was examined using asymptomatic persimmon leaves and collected ascospores using spore traps followed by RT-PCR and nested PCR assay in 2015. As the results, M. nawae was detected before mid of May, and the concentration was gradually increased until mid of June. Quantitative analysis of scattered ascospore using RT-PCR and nested PCR showed similar patterns. Furthermore, the concentration of ascospore increased rapidly at the end of October, during the harvest period. Due to the symptoms of circular leaf spot appearing in early August in Korea, fungicide treatment at the end of June is most recommended. Therefore, based on our results, to control the leaf spot a fungicide treatment should be applied from mid of May. And it is confirmed that RT-PCR can predict the primary infection period, distribution and mass of ascospore in persimmon orchards.