Occurrence and molecular characterization of Diaporthe eres causing stem canker on sweet cherry trees (Prunus avium) in northern China

Sweet cherry (Prunus avium) is a commercially important species in China, experiencing a rapid increase in production. In June 2022, a severe infection, affecting more than 8% of sweet cherry trees, was observed on the Tetian cultivar in a 2-3-year-old orchard in Dalian City, northern China. Initially, spindle-shaped brown disease spots formed on the surfaces of the branches. These spots continued to spread and merge, and the middle portion of the cankers sunk inward and gradually dried. Small black particles were found on the surface of the stems. The disease spread was more prevalent during the rainy season, leading to the withering of numerous branches and the death of the whole plant. Seven isolates, named lncy1-1, lncy4-1, lncy5-1, lncy6-1, lncy7-1, lncy8-1 and lncy9-1, were obtained from 24 disease samples. Phylogenetic analysis based on three loci (rDNA ITS, TEF1 and TUB2) coupled with morphological identification confirmed that these seven isolates belong to Diaporthe eres. A representative isolate, lncy1-1, was inoculated onto sweet cherry branches in a controlled environment, and showed that the isolate lncy1-1 was pathogenic. The fungus isolated from diseased tissues was identified as D. eres based on morphological and molecular criteria. To the best of our knowledge, this is the first report of stem canker in sweet cherry caused by D. eres in China, which will promote disease management and expand the known host range of D. eres.