First report of Fusarium oxysporum causing fruit spot disease on Prunus salicina in China and evaluation of effective fungicides for control

The Asian plum ( Prunus salicina ) is widely cultivated in China for its nutritional and economic importance. In 2024, a previously unreported fruit spot disease was observed on plums in Guizhou Province, China; affected fruit developed depressed lesions that progressed to rot, resulting in substantial economic losses. The causal agent was identified as Fusarium oxysporum based on morphology and a multilocus phylogenetic analysis of TEF1-α , RPB2 , and TUB2 . Pathogenicity assays that fulfilled Koch's postulates confirmed F. oxysporum as the etiological agent of the disease. Fungicide sensitivity of the F. oxysporum isolate was evaluated using the mycelial growth rate method across 13 active ingredients, and field efficacy trials were conducted with six fungicides. Prochloraz (45.0 % EW), tebuconazole (43.0 % SC), and azoxystrobin (25.0 % SC) strongly inhibited mycelial growth, with EC 50 values of 0.0570, 0.0810, and 0.0592 μg mL, respectively. In field trials, prochloraz (45.0 % EW) and tebuconazole (43.0 % SC) provided excellent control of plum fruit spot, with control efficacies of 80.31 % and 78.39 % at 7 days and 76.55 % and 73.50 % at 14 days after the final application, respectively. To the present knowledge, this is the first report of F. oxysporum causing fruit spot on plum in China, and the results identify effective chemical options for disease management.