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European Journal of Plant Pathology

, Volume 134, Issue 2, pp 357–365 | Cite as

Inactivation of Phytophthora and bacterial species in water by a potential energy-saving heat treatment

  • W. Hao
  • M. O. Ahonsi
  • B. A. Vinatzer
  • C. Hong
Article

Abstract

Plant pathogens, especially Phytophthora and bacterial species, in re-circulated irrigation water present a significant health risk to nursery and greenhouse crops. Heat treatment at 95°C for 30 s is one of the most reliable technologies for irrigation water decontamination. The primary objective here was to examine whether the water temperature required to inactivate major pathogens in re-circulated irrigation water can be lowered from 95°C to conserve energy and improve horticultural profitability while reducing environmental footprint. Specifically, we investigated the effect of water temperature on Phytophthora nicotianae zoospore survival in the laboratory and on annual vinca under greenhouse conditions. We also assessed the effect of water temperature on survival of chlamydospores of P. nicotianae, oospores of P. pini, six plant pathogenic bacterial species and Escherichia coli. The zoospores of P. nicotianae did not survive and cause any disease on annual vinca when exposed to 42°C for 12 h or 48°C for 6 h. No chlamydospores of P. nicotianae survived 42°C for 24 h or 48°C for 6 h, nor did the oospores of P. pini at 42°C for 12 h or 48°C for 6 h. In addition, none of the seven bacterial species survived 48°C for 24 h. These results indicate that the required water temperature to eliminate Phytophthora and bacterial species may be lowered substantially from 95°C by longer exposure time, improving the economics and environmental footprint, without sacrificing efficacy of heat treatment.

Keywords

Chlamydospore Nursery and greenhouse crops Oospore Re-circulated irrigation water Zoospore 

Notes

Acknowledgements

This work is partly supported by the Fred C. Gloeckner Foundation, Inc and a grant from the USDA National Institute of Food and Agriculture - Specialty Crop Research Initiative (Agreement #: 2010-51181-21140). We would like to thank Dr. Anton Baudoin, Dr. Erik Stromberg, and Dr. Michael Benson for their valuable advices on this study, and we also would like to thank Patricia Richardson, Xiao Yang, and Lauren Achtemeier for assisting with the greenhouse experiments.

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Copyright information

© KNPV 2012

Authors and Affiliations

  • W. Hao
    • 1
    • 3
  • M. O. Ahonsi
    • 1
    • 2
  • B. A. Vinatzer
    • 3
  • C. Hong
    • 1
    • 3
  1. 1.Hampton Roads Agricultural Research and Extension CenterVirginia TechVirginia BeachUSA
  2. 2.Energy Biosciences Institute, Institute for Genomic BiologyUniversity of IllinoisUrbanaUSA
  3. 3.Department of Plant Pathology, Physiology, and Weed ScienceVirginia TechBlacksburgUSA

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