European Journal of Plant Pathology

, Volume 153, Issue 3, pp 907–914 | Cite as

Inactivation of plant pathogens in irrigation water runoff using a novel UV disinfection system

  • Bassam A. YounisEmail author
  • Laura Mahoney
  • Wolfgang Schweigkofler
  • Karen Suslow


Untreated recycled irrigation water has been shown to introduce and spread plant pathogens such as Pythium and Phytophthora in commercial nurseries. Nevertheless, few nurseries currently treat their recycled irrigation water. Instead, nurseries use prophylactic pesticides to control the spread of plant pathogens, which increases costs and promotes the growth of resistant pathogens. Of interest to California is the spread of Phytopthora ramorum, causal agent of Sudden Oak Death (SOD), responsible for the death of tens of thousands of trees in California and Oregon. This study investigated the use of a novel UV disinfection system to inactivate P. ramorum and other microbial contaminants at the National Ornamental Research Site at the Dominican University of California (NORS-DUC). In this system, the UV lamps do not come in contact with the water and hence remain free of the ‘lamp fouling’ problem. Tests on waters having the same characteristics as run-off from commercial nurseries showed a minimum of 3.7 log removal of bacterial species, 91.7% reduction of fungal counts, and 100% inactivation of the P. ramorum in the effluent. Treating the run-off from plant nurseries limits the spread of plant pathogens and enables the onsite re-use of the run-off.


Phytopthora ramorum UV disinfection Vortex reactor Irrigation run-off Nursery plants 



This work was funded by the Sustainability Training and Research Program (SRTP), University of California – Davis, and by Diamond Developers, The Sustainable City - Dubai. We thank Dr. Suprya Shama (NORS-DUC) for technical assistance in the NORS-DUC lab.

Compliance with ethical standards

Ethical approval

The authors declare that this manuscript reports on original research that has not been published elsewhere. All the authors have read and approved this manuscript. All authors also declare that the data have not been manipulated. This manuscript does not contain any experiments with human participants or with animals.

Conflict of interest

The authors declare that they have no actual or potential conflict of interest.


  1. Abu-Orf, M., Tchobanoglous, G., Stensel, H. D., Tsuchihashi, R., Burton, F., Bolton, G. (2014). Wastewater engineering: Treatment and resource recovery. McGraw Hill Education, New York.Google Scholar
  2. Ali-Shtayeh, M., & MacDonald, J. (1991). Occurrence of Phytophthora species in irrigation water in the Nablus area (West Bank of Jordan). Phytopathologia Mediterranea, 30, 143–150.Google Scholar
  3. APHA (2005). Standard methods for the examination of water and wastewater. In (21st ed.). American Public Health Association/American Water Works Association/Water Environment Federation Washington, DC.Google Scholar
  4. Banihashemi, Z., MacDonald, J. D., & Lagunas-Solar, M. C. (2010). Effect of high-power monochromatic (pulsed UV laser) and low-power broadband UV radiation on Phytophthora spp. in irrigation water. European Journal of Plant Pathology, 127(2), 229–238.CrossRefGoogle Scholar
  5. Bolton, J. R., & Linden, K. G. (2003). Standardization of methods for fluence (UV dose) determination in bench-scale UV experiments. ASCE Journal of Environmental Engineering, 129, 209–216.CrossRefGoogle Scholar
  6. Crittenden, J. C., Trussel, R. R., Hand, D. W., Howe, K. J., & Tchobanoglous, G. (2003). Water treatment: Principles and design (2nd ed.). Hoboken: Wiley.Google Scholar
  7. Erwin, D. C., & Ribeiro, O. K. (1996). Phytophthora diseases worldwide. St. Paul: APS Press.Google Scholar
  8. Ferguson, A. J., & Jeffers, S. N. (1999). Detecting multiple species of Phytophthora in container mixes from ornamental crop nurseries. Plant Disease, 83(12), 1129–1136.CrossRefGoogle Scholar
  9. Ghimire, S. R., Richardson, P. A., Kong, P., Hu, J., Lea-Cox, J. D., Ross, D. S., Moorman, G. W., & Hong, C. (2011). Distribution and diversity of Phytophthora species in nursery irrigation reservoir adopting water recycling system during winter months. Journal of Phytopathology, 159(11–12), 713–719.CrossRefGoogle Scholar
  10. Grünwald, N. J., Garbelotto, M., Goss, E. M., Heungens, K., & Prospero, S. (2012). Emergence of the sudden oak death pathogen Phytophthora ramorum. Trends in Microbiology, 20(3), 131–138.CrossRefGoogle Scholar
  11. Hong, C. X., & Moorman, G. W. (2005). Plant pathogens in irrigation water: Challenges and opportunities. Critical Reviews in Plant Sciences, 24(3), 189–208.CrossRefGoogle Scholar
  12. Hong, C., Richardson, P., Kong, P., & Bush, E. (2003). Efficacy of chlorine on multiple species of Phytophthora in recycled nursery irrigation water. Plant Disease, 87(10), 1183–1189.CrossRefGoogle Scholar
  13. Johnson-Brousseau, S., Henkes, M., Kosta, K., Suslow, K., Posadas, A., & Ghosh, S. (2011). Phytophthora ramorum research at the National Ornamental Research Site at the Dominican University of California. New Zealand Journal of Forestry Science, 41, 101–113.Google Scholar
  14. Jung, T., Orlikowski, L., Henricot, B., Abad-Campos, P., Aday, A. G., Aguín Casal, O., Bakonyi, J., Cacciola, S. O., Cech, T., & Chavarriaga, D. (2016). Widespread Phytophthora infestations in European nurseries put forest, semi-natural and horticultural ecosystems at high risk of Phytophthora diseases. Forest Pathology, 46, 134–163.CrossRefGoogle Scholar
  15. Kong, P., Hong, C., Jeffers, S. N., & Richardson, P. A. (2003). A species-specific polymerase chain reaction assay for rapid detection of Phytophthora nicotianae in irrigation water. Phytopathology, 93(7), 822–831.CrossRefGoogle Scholar
  16. Kovacs, K., Holmes, T. P., Englin, J. E. & Alexander, J. (2011). The dynamic response of housing values to a forest invasive disease: Evidence from a sudden oak death infestation. Environmental and Resource Economics, 49 (3), 445–451.Google Scholar
  17. Lamour K. (Ed.) (2013). Phytophthora: A global perspective. CABI Plant Protection Series; 2, Wallingford, UK.Google Scholar
  18. Mislivec, P. B., & Bruce, V. R. (1976). Comparison of antibiotic-amended potato dextrose agar and acidified potato dextrose agar as growth substrates for fungi. Journal of the Association of Official Analytical Chemists, 59(3), 720–721.Google Scholar
  19. NWRI. (2012). Ultraviolet disinfection guidelines for drinking water and water reuse. In G. M. Vartanian (Ed.). Fountain Valley: National Water Research Institute.Google Scholar
  20. Orlikowski, L. B., Oszako, T., Trzewik, A., & Orlikowska, T. (2007). Occurrence of Phytophthora ramorum and other Phytophthora species in nurseries, trade stands, forests and water. Journal of Plant Protection Research, 47(4).Google Scholar
  21. Reasoner, D. J., & Geldreich, E. E. (1985). A new medium for the enumeration and subculture of bacteria from potable water. Applied and Environmental Microbiology, 49(1), 1–7.Google Scholar
  22. Rizzo, D. M., & Garbelotto, M. (2003). Sudden oak death: endengaring California and Oregon forest ecosystems. Frontiers in Ecology and the Environment, 1(4), 197–204.Google Scholar
  23. Van der Linde, K., Lim, B. T., Rondeel, J. M. M., Antonissen, L. P. M. T., & de Jong, G. M. T. (1999). Improved bacteriological surveillance of haemodialysis fluids: A comparison between tryptic soy agar and Reasoner's 2A media. Nephrology Dialysis Transplantation, 14(10), 2433–2437.CrossRefGoogle Scholar
  24. Werres, S., Wagner, S., Brand, T., Kaminski, K., & Seipp, D. (2007). Survival of Phytophthora ramorum in recirculating irrigation water and subsequent infection of Rhododendron and viburnum. Plant Disease, 91(8), 1034–1044.CrossRefGoogle Scholar
  25. Widmer, T. L. (2009). Infective potential of sporangia and zoospores of Phytophthora ramorum. Plant Disease, 93(1), 30–35.CrossRefGoogle Scholar
  26. Younis, B. A. (2014). Demonstrating a vortex technology to disinfect wastewater with ultraviolet light. Report to California Energy Commission, CR 500-09-050 (also US patent publication number US 2016/0176727 A1, 2016).Google Scholar

Copyright information

© Koninklijke Nederlandse Planteziektenkundige Vereniging 2018

Authors and Affiliations

  • Bassam A. Younis
    • 1
    Email author
  • Laura Mahoney
    • 1
  • Wolfgang Schweigkofler
    • 2
  • Karen Suslow
    • 2
  1. 1.Department of Civil and Environmental EngineeringUniversity of California DavisDavisUSA
  2. 2.Department of Science and MathematicsDominican University of CaliforniaSan RafaelUSA

Personalised recommendations