1. Management of Fusarium root rot on carrots
Kevin Vander Kooi
Mary Ruth McDonald
Ahmed Abdelmagid
Michael Tesfaendrias

2. Fusarium Root Rot of Carrot
Fusarium root rot was identified in the Holland Marsh, Ontario in 2008
Fusarium solani is a soil-borne pathogen but can also be associated with seed
This disease infects both the root and crown of carrots, significantly reducing the marketable yield
Currently, there is no registered fungicides to control the disease
Fusarium solani macro and micro condia

3. Project Objectives
Field trials were conducted between 2011 and 2015 in carrot fields with a history of the disease to:
Evaluate the susceptibility of carrot cultivars to Fusarium root rot in field
Screen fungicides for effectiveness in controlling the disease
Evaluate soil fumigants

4. Screening Trials 2011-2013 2011- two fungicides:
Maxim (fludioxonil 21%) Field 1
Scholar (fludioxonil 230 g/l) Field 2
2013 – five products (In-furrow)
Emesto Silver (Penflufen 9.4% and Prothioconazole1.7%)
Mertect (Thiabendazole 42.3%)
Folicur (Tebuconazole 43% )
Heads Up (Saponins of Chenopodium quinoa 49.65%)
Trichoderma atroviride
– Variety Trials
Field trials
Lab trials

5. Fungicide Trial 2011 NS

6. Fungicide Trial 2013
September
Harvest

7. Results
Disease infects carrots late in season in the field and can cause significant yield losses
None of the fungicides or biologicals reduced disease incidence
Fusarium solani was identified as the pathogen

8. Fusarium root rot lab trial
Cellobunch vs Isolate 2
Envy vs Isolate 1
Fontana vs Isolate 2

9. Variety trial in lab Fusarium solani (isolate 1)
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bcd cd d e a de

10. Variety trial in lab Fusarium solani (isolate 2)bc cd d e

11. Cultivar field trial NS ns

12. Variety Trial Results
Identified different isolates of the pathogen in the Holland Marsh
Different isolates of the pathogen infected carrot cultivars under controlled conditions and caused disease
All carrot cultivars tested were susceptible to Fusarium

13. Evaluation of Pic Plus fumigant for control Fusarium root rot
Pic Plus (Chloropicrin 85%)
Labelled for use in carrots in 2012
Affects a broad spectrum of fungi, nematodes, insects
Injected into soil prior to seeding carrots
Broadcast and banded applications of 108 L/ha
Use in Bradford/Holland Marsh spring 2013
Issues with product in summer of 2013 in SW Ontario
In 2014 PMRA requirements for fumigants changed

14. Pic Plus Applications Banded application Applied at seeding
Tested several rates

15. Evaluation of Pic Plus-2014

16. Marketable yield following treatment with Pic Plus
Marketable Yield t/ha

17. 2015 Harvest Results Several rates tested
Applied at seeding under the carrots
108 L/ha reduced disease
Issue with quality – forked roots

18. 108 L/ha

19. Check

20. 54 L/ha

21. 70 L/ha

22. Fumigant Results
Pic Plus is the only product that significantly decreased the disease incidence under field conditions
Higher rates up to 108 L/ha reduced disease incidence and severity
Use of high rate at seeding caused forking

23. Recommendations If using high rate delay seeding for several days
Avoid late harvest
As the plants mature and carrots bulk up the roots become more susceptible to root rot
Minimizing stress
Anything that stresses the plant such as herbicide injury, or drought may make it more susceptible to root rot
Further research is needed to find effective rates to decrease Fusarium severity

24. Thank you Annual Muck Growers Conference April 12-13 Bradford Ontario
All research reports available online

25. Acknowledgments TriEst Ag Group Inc. (Douglas Ag Services)
HMGA through the Bradford Coop
Plant Productions systems of the OMAFRA and University of Guelph partnership
Cooperating growers