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Keywords:

  • disease complex;
  • biocontrol;
  • Meloidogyne incognita;
  • Phytophthora nicotianae;
  • tobacco

Abstract

BACKGROUND

The use of dually antagonistic bacteria (DAB) as alternatives to chemicals for biological control of disease complexes has received little attention. In this study targeting the Meloidogyne incognita–Phytophthora nicotianae complex, DAB from the tobacco rhizosphere were identified and screened against the diseases caused by one or both pathogens in tobacco.

RESULTS

From 450 soil tobacco rhizosphere samples, 26 DAB were identified and had in vitro nematicidal and antifungal efficacies of 37.2–100% and 32.9–73.4% respectively. These DAB were classified into 19 species of 11 genera. In pot experiments, Streptomyces flavofungini SNA26, Pseudomonas putida SNB53 and Serratia marcescens subsp. sakuensis SNB54 effectively suppressed black shank (control effect 72.0–80.2%), root knot (70.0–81.7) and the disease complex (58.7–68.5%) caused by P. nicotianae, M. incognita and both pathogens in tobacco respectively.

CONCLUSION

Nineteen DAB species were demonstrated to be antagonists against the M. incognita–P. nicotianae complex. Because S. flavofungini SNA26, P. putida SNB53 and S. marcescens subsp. sakuensis SNB54 significantly suppressed the infection of M. incognita and P. nicotianae in tobacco, these species have potential for development as biocontrol agents against the diseases and complex caused by these two pathogens. © 2014 Society of Chemical Industry