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Co-application of dazomet and azoxystrobin reconstructs soil microbial communities and suppresses the violet root rot of Codonopsis tangshen under a continuous cropping system

Summary

Codonopsis tangshen is an important medicinal plant in China, but it suffers from a serious fungal disease called violet root rot when grown repeatedly in the same soil. Researchers found that treating soil with dazomet fumigant followed by azoxystrobin fungicide completely eliminated this disease while dramatically increasing plant yields. The treatment works by reducing the harmful fungus while promoting growth of beneficial soil microbes that naturally suppress disease.

Background

Violet root rot (VRR) is a devastating soil-borne disease caused by Helicobasidium pathogens that severely affects Codonopsis tangshen production under continuous cropping systems. Limited effective control strategies are available for VRR management. The disease can cause yield reductions up to 50% in mild cases and complete crop failure in severe cases.

Objective

This study aimed to evaluate the efficacy of dazomet fumigation alone and in combination with azoxystrobin in controlling VRR in continuously cropped C. tangshen. The research examined effects on yield, VRR incidence, medicinal components, soil biochemical properties, and rhizosphere microbial community structure.

Results

DA treatment completely prevented VRR occurrence in both years while increasing yield by 173.8% in 2019 and 520.9% in 2020. DA significantly decreased pathogenic Helicobasidium abundance and increased beneficial microbes (Rhodanobacter, Saccharimonadales, Acidothermus, Tetracladium). The treatments altered soil biochemical properties and shifted microbial community structure, with DA exhibiting superior disease control compared to dazomet alone.

Conclusion

Co-application of dazomet and azoxystrobin effectively controlled VRR through two mechanisms: direct reduction of pathogen density and reconstruction of disease-suppressive microbial communities. This integrated approach provides an effective, sustainable strategy for managing VRR in C. tangshen cultivation with potential for broader agricultural applications.
  • Published in:Microbiology Spectrum,
  • Study Type:Field Experiment,
  • Source: PMID: 40698824, DOI: 10.1128/spectrum.01088-25
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