Identification, pathogenic mechanism and control of Stagonosporopsis cucurbitacearum causing post-harvest fruit rot in melon.

Background: Fruit rot, caused by a range of pathogens, represents one of the most devastating post-harvest diseases of melon (Cucumis melo L.). In 2023, we isolated a pathogenic fungus, identified as Stagonosporopsis cucurbitacearum, from infected melon fruits at the a melon cultivation site in Heilongjiang Province, China.

Results: This is the first report of S. cucurbitacearum causing post-harvest fruit rot in melons in China. S. cucurbitacearum isolates causing melon fruit rot promoted cell wall-degrading enzyme activities. Rapid degradation of host cell walls by these enzymes was associated with flesh softening and the rapid proliferation of S. cucurbitacearum, and was probably the main determinant of this fungus as a pathogen. Carbendazim and tebuconazole, the most effective fungicides, completely inhibited sporangioconidial germination at 0.00049 and 0.00161 mg L, respectively, and inoculating melon fruit with these fungicides at 0.000625 and 0.000172 mg L reduced disease incidence by approximately 70%.

Conclusions: On the basis of our findings regarding the pathogenic mechanisms, host range and chemical control, we recommend: (i) application of appropriate concentrations of carbendazim or tebuconazole on the surface of muskmelons during the pre-harvest safety period, and (ii) maintaining melon fruits separate from the fruits of other hosts during storage and transportation. © 2025 Society of Chemical Industry.