Journal of Plant Diseases and Protection

, Volume 117, Issue 3, pp 102–109 | Cite as

Antimicrobial activity of phosphites against different potato pathogens

  • M. C. LobatoEmail author
  • F. P. Olivieri
  • G. R. Daleo
  • A. B. Andreu


Phosphites have low-toxicity on the environment and show high efficacy in controlling oomycete diseases in plants, both by a direct and an indirect mechanism. We have shown that they are also effective in reducing disease symptoms produced by Phytophthora infestans, Fusarium solani and Rhizoctonia solani when applied to potato seed tubers. To gain better insight into the direct mode of action of phosphites on different potato pathogens, and to ascertain chemical determinants in their direct antimicrobial activity, four potato pathogens were assayed with respect to sensitivity toward calcium, potassium and copper phosphites (CaPhi, KPhi and CuPhi, respectively). The influence of acidification and ionic strength changes after Phi addition on the antimicrobial activity, and the fungicidal or fungistatic activity, were evaluated. Results showed that phosphites were able to inhibit growth of all pathogens. Phytophthora infestans was the most inhibited pathogen by all phosphites, followed by Streptomyces scabies, while Rhizoctonia solani and Fusarium solani were less inhibited. CuPhi had the highest antimicrobial activity against the four pathogens analysed, and CaPhi and KPhi showed similar antimicrobial activities. Inhibitions by CuPhi and CaPhi could be partially explained by acidification of the media. However, results obtained with KPhi demonstrated that the phosphite anion has antimicrobial activity itself. The increase in ionic strength after Phi addition was not important in the antimicrobial activity of Phi. The activity of phosphites on germination of F. solani spores showed to be fungistatic rather than fungicidal.

Key words

disease control Fusarium solani growth inhibition Phytophthora infestans Rhizoctonia solani Streptomyces scabies 

Antimikrobielle Aktivität von Phosphiten gegenüber verschiedenen Kartoffelpathogenen


Phosphite besitzen eine geringe Umwelttoxizität sowie eine gute direkte und indirekte Wirkung gegenüber Oomyceten- Pathogenen von Pflanzen. Wir zeigen hier, dass sie ebenfalls die durch Phytophthora infestans, Fusarium solani and Rhizoctonia solani verursachten Symptome an Kartoffeln nach einer Knollenbehandlung vermindern. Vier Kartoffelpathogene wurden mit dem Ziel untersucht, die direkte Wirkungsweise von Calcium-, Kalium- und Kupfer-Phosphiten (CaPhi, KPhi und CuPhi) auf die Erreger sowie die chemischen Determinanten ihrer direkten antimikrobiellen Aktivität zu ermitteln. Weiterhin wurde die Wirkung von Azidifizierung und Ionenstärke nach Zugabe von Phosphiten auf antimikrobielle, fungizide und fungistatische Aktivität untersucht. Die Phosphite beeinträchtigten das Wachstum aller untersuchten Erreger. Phytophthora infestans wurde durch alle verwendeten Phosphite am stärksten inhibiert, gefolgt von Streptomyces scabies, während die Wirkung auf Rhizoctonia solani und Fusarium solani geringer war. CuPhi besaß die höchste antimikrobielle Aktivität gegenüber den vier untersuchten Pathogene, gefolgt von den ähnlich wirksamen CaPhi und KPhi. Die Wirkung von CuPhi und CaPhi kann zum Teil durch die Ansäuerung der verwendeten Medien erklärt werden. Die mit KPhi erhaltenen Ergebnisse zeigen dagegen, dass das Phosphit-Anion selbst antimikrobiell wirksam ist. Die Zunahme der Ionenstärke nach Phosphit-Applikation war nicht für die antimikrobielle Wirkung verantwortlich. Die Beeinträchtigung der Sporenkeimung von F. solani zeigte, dass die Wirkung der Phosphite eher fungistatisch als fungizid ist.


Fusarium solani Krankheitsbekämpfung Phytophthora infestans Rhizoctonia solani Streptomyces scabies Wachstumsbeeinträchtigung 


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Copyright information

© Deutsche Phythomedizinische Gesellschaft 2010

Authors and Affiliations

  • M. C. Lobato
    • 1
    Email author
  • F. P. Olivieri
    • 1
  • G. R. Daleo
    • 1
  • A. B. Andreu
    • 1
  1. 1.Instituto de Investigaciones Biológicas, Facultad de Ciencias Exactas y NaturalesUniversidad Nacional de Mar del PlataMar del PlataArgentina

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