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Rhizoctonia solani causes okra (Abelmoschus esculentus) seedling damping-off in South China with biological characterization and fungicide sensitivity profiling

Summary

Researchers identified Rhizoctonia solani as the fungus causing a serious disease in okra seedlings in southern China that was destroying about 35% of crops. The fungus dies when exposed to high temperatures (45-48°C) and grows best at about 28°C. Among seven tested antifungal treatments, a combination of trifloxystrobin and tebuconazole was most effective at controlling the pathogen, providing farmers with practical strategies for managing this crop disease.

Background

Okra is an important vegetable crop cultivated globally for its nutritious pods, but it faces emerging threats from seedling damping-off and blight in subtropical regions of South China. A severe outbreak with 35% disease incidence was observed in Guangdong Province in 2022, with the causative pathogen initially unidentified.

Objective

To identify the fungal pathogen causing okra seedling damping-off in South China, characterize its biological properties including thermal tolerance, and evaluate its sensitivity to commercial fungicides for effective disease management.

Results

Three Rhizoctonia solani isolates were identified as the primary causal agent of damping-off. The pathogen showed mycelial and sclerotial lethal temperatures of 45°C and 48°C respectively, with optimal growth temperature of 28.22°C. Among seven tested fungicides, trifloxystrobin + tebuconazole (1:2) showed the highest efficacy with mean EC50 value of 0.43 mg·L⁻¹.

Conclusion

R. solani is confirmed as the primary pathogen causing okra damping-off in South China, representing the first conclusive evidence in East Asia. The study provides critical insights for disease management through soil solarization above 48°C, targeted fungicide application with trifloxystrobin + tebuconazole, and temperature-adjusted planting schedules.
  • Published in:Scientific Reports,
  • Study Type:Experimental Study,
  • Source: 10.1038/s41598-025-14836-w
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