1. Aqueous Ozone in Nursery and Greenhouse Production Systems
Addressing the Threat of Sudden Oak Death & Other
Plant Pathogens with Aqueous Ozone Technologies
Thomas Graham1, Michael Dixon1, Youbin Zheng1, Weizong Liu1,
Ping Zhang1, Diane Cayanan1, Aaron Cena2, Laura Greenway2, Dave Greenway2, Jennifer Llewellyn3
1 University of Guelph, Department of Environmental Biology,
Guelph, Ontario, Canada. N1G 2W1
2 Purification Research Technologies Incorporated, 400 Southgate Drive,
Guelph, Ontario, Canada. N1G 4P5
3 Ontario Ministry of Agriculture Food and Rural Affairs
Will be focusing on the nursery applications but many of the concepts are applicable to greenhouse production as well

2. Outline Some Greenhouse & Nursery Stats
Sudden Oak Death & Other Beasties
What, Where & Why
What’s on the Go
‘Bench’ trials
Coming Soon…
Commercial Trial Plans
Summary

3. Industry Significance
Farmgate value over $2.7 billion
Economic influences beyond $4 billion
Courtesy of Statistics Canada, 2004
Does not include vegetable greenhouse production…add another ¾ billion

4. Issues in the Industries
Legislation/Regulation
Nutrient Management Act; Source Water Protection Act; US/Global Market Access
Environmental & Social
Ecosystem protection; ‘Good Neighbours’
Economic
Resource utilization efficiency
Low cost foreign imports/competition
The Ubiquitous Pathogen Threat!
As with all industries, there are issues to contend with
Drinking water protection
Tightening border restrictions
Increasing labour and energy costs
Low cost foreign competition
Pathogens…One pathogen in particular is currently giving the nursery growers insomnia

5. Sudden Oak Death If you have it… Phytophthora ramorum
Quarantine
Trade restrictions
Crop destruction
Bankruptcy
Can wipe out entire tracts of forest
Pathogen of particular interest is the casual agent of SOD
Threat is not so much that it will wipe out nursery species, but rather the regulations will. The real biological threat is to our natural forests

6. Forest Threat
Western Sonoma County, summer near Table Mountain, west of Cazadero Photo courtesy of Dave Rizzo, UC Davis

7. SOD distribution

8. California Oak Mortality Task Force
SOD Distribution
California Oak Mortality Task Force

9. Other Pathogens of Concern
Phytophthora
Pythium spp.
Fusarium spp.
Phytophthora spp.
Rhizoctonia spp.
Powdery Mildews
Fusarium
Powdery Mildews

10. Residual is left and water is applied to the crop?
Working Premise
Ozone can be used to address pathogen proliferation & water use efficiency issues in the greenhouse & nursery industries
Standard Approach
Treat irrigation water
Treat run-off water
But what happens if…
This is all and well, but we need to know now is the best way to go about it…and we need to be able to convey this to the growers
Residual is left and water is applied to the crop?

11. IF we leave a residual… What are the phytotoxicity levels?
Is off-gassing going to be a problem?
Can foliar pathogens be controlled?
Can hardware handle it?
etcetera

13. Nursery Bench Trials Determining appropriate application levels
Five economically significant nursery crops
Five treatment levels (control; 0.5; 1.5; 3.0; 6.0 mg/l)
Split-plot design

14. Test System
Raw Water

15. Response to Ozone Application

16. Sample of Leaf Injury

17. Ozone Loss During Irrigation

18. Pathogen Control Capacity
Are the levels of ozone that are plant safe sufficient to control the pathogens?

19. At least in some cases… Currently looking at; Pythium spp.
Fusarium spp.
Phytophthora spp.
Rhizoctonia spp.
Powdery Mildews

20. Early Results

21. Outline Coming Soon… Commercial Trial Plans
The Greenhouse & Nursery Industries (in Canada)
Sudden Oak Death & Other Beasties
What, Where & Why
What’s on the Go
‘Bench’ trials
Coming Soon…
Commercial Trial Plans
Summary

22. The Next Step Summer 2007 Complete ‘loop’ scale up
Nursery commercial trials
Initial small volume trial; rising to 0.6+Ml/d
Greenhouse trials
Begonia operation
Cut rose operation
Complete ‘loop’ scale up
Evaluate pathogen control

23. Commercial Trials
Greenhouse
Nursery

24. Scaling Up
1000’s litres litres/day
10 000’s litres/day

25. Summary Nursery bench trial results Engineering work to be done
Direct application of O3(aq) is possible but needs to be tested on the species of interest
Promising for foliar/root pathogen management
Engineering work to be done
Balance doses needed to treat water with residual levels that do not result in phytotoxicity
Lots of work yet to be done
Monitor foliar pathogens under ozonation
Expand the number of species tested
Investigate other production systems
NFT, drip, flooding etc.

26. Canadale Nurseries Inc. (Tom Intven)
Thanks To
Earth and Environmental Technologies
Agricultural Adaptation Council (Agriculture & Agrifood Canada; Ontario Ministry of Agriculture Food and Rural Affairs)
Matt Hannaberg
Canadale Nurseries Inc. (Tom Intven)

27. Thank you for your attention!
Questions?