Plums are commercially cultivated worldwide for the rich nutrient value of their fruit. In May 2019, plums with symptoms of fruit rot were collected from fields located in Liuma town, Guizhou Province, China. The incidence of the disease varied from 10 to 20%, which was observed in 15 plum orchards (18 hectares) surveyed. Estimated yield loss was from 5 to 10% for each field. Diseased fruits showed deformity, wilting and sunken lesions, and subsequently became melanized and rotted.
Scientists at Guizhou University have collected diseased tissues and conducted morphological analyses. Based on the cultural and conidial morphology, the isolates were identified as Fusarium fujikuroi. To confirm the morphological diagnosis, DNA sequencing and pathogenicity assay were performed.
"Fruit were artificially inoculated and maintained in a growth chamber with 90% relative humidity at 25°C, and a daily 12-h photoperiod. After 5 days, the artificially inoculated fruit showed blotches with sunken lesions similar to those observed in the orchards, whereas no symptoms were observed on the control fruit. The experiment was repeated twice with similar results. Fusarium fujikuroi was reisolated from infected tissues and confirmed by sequence analysis. To our knowledge, this is the first report of F. fujikuroi causing fruit blotch of plum in China. Considering the economic importance of plum in China and throughout the world, F. fujikuroi may be an emerging problem for plum cultivation. Thus, further study of fruit blotch of plums is warranted," the scientists explain.
Source: Haijiang Long, Xianhui Yin, Zhibo Zhao, Youhua Long, Juan Fan, Ran Shu, Guifei Gu, 'First Report of Fruit Blotch on Plum caused by Fusarium fujikuroi in China', 2021, Plant Disease.