Abstract:Background Curcuma kwangsiensis, a valuable medicinal crop in Guangxi, China, suffers serious yield losses due to leaf spot disease caused by fungal infections, necessitating precise identification of the causal pathogen and effective control strategies to support growers’ economic sustainability.Objective To identify the fungal pathogen causing leaf spot disease in C. kwangsiensis, characterize its biological properties, and evaluate the disease management effects of fungicides.Methods Diseased leaves from C. kwangsiensis in Nanning, Guangxi were sampled, and fungal strains were isolated via tissue culture and single-spore isolation techniques. Pathogenicity of the isolates was confirmed according to Koch’s postulates. The pathogen was identified through morphological characterization and multi-locus phylogenetic analysis (ITS, EF-1α, TUB, HIS, and CAL). Growth responses of the isolates to varying environmental conditions and sensitivity to five common fungicides were assessed.Results Isolates CK30.1 and CK36.2 were confirmed as the causal agents of leaf spot disease and identified as Diaporthe passifloricola. The fungus exhibited optimal growth on the PDA medium at 28 ℃ and pH 6.0, with mycelial death occurring after incubation in a 10 min water bath at 52 ℃. Among five tested fungicides, 50% carbendazim and 75% tebuconazole·trifloxystrobin showed the highest efficacy, with EC50 values of 0.15 mg/L and 0.17 mg/L, respectively.Conclusion This study confirms D. passifloricola as a novel pathogen causing leaf spot disease of C. kwangsiensis in Guangxi and recommends 50% carbendazim and 75% tebuconazole·trifloxystrobin as highly effective fungicides, providing a foundation for targeted disease management in the field.
