Luis del Río North Dakota State University

1. Developing a Sclerotinia stem rot warning system for canola in North Dakota Luis del Río North Dakota State University

3. Photo: www.canolacouncil.org Photo: www.canolacouncil.org

4. North Dakota canola producing areas Cavalier Kittson Divide Burke Rosseau Renville Bottineau Rolette Towner Pierce McHenry Ramsey Williams Marshall Mountrail Pennington Ward Warren Benson Nelson Red Lake Eddy Sheridan Wells Foster Griggs McLean Stutsman Fargo

5. A. Lamey Sclerotinia stem rot disease cycle (Sclerotinia sclerotiorum)

6. Model development Disease data collection • Annual field survey (third wk August) • 206 fields from 25 locations per year • SSR incidence on 50 plants per field • SSR mean incidence per location/ year

7. Model development Weather data collection • NDAWN stations • Hourly data on air and soil temp, solar radiation, dew temp, wind speed, etc. • Means and new variables created by periods of 15 days

8. Model development Model development and validation • Logistic regression analysis • Model produced using 177 data points collected between 2001 and 2006 • Model validation using cross-validation option of SAS

9. Model development Model forecasting • Risk of SSR development calculated every 3 days • Color maps available to growers through web site during canola flowering period

10. Results Incidence of Sclerotinia stem rot of canola in North Dakota between 1995 and 2008 Incidence (%) Years

11. Results • Most important weather variables were precipitation and solar radiation • Three models developed, one for second half of June, one for first half of July and a general model

12. Results y= 4.08+0.05(rain3)+0.07(rain4)-0.55(solar4)+0.53(rain5) -0.20(solar5)+0.38(rain6) Parameters Model 1 Model 2 Model 3 Percent concordance77 80 83 Percent discordance23 20 17 Somers’ D 0.54 0.59 0.66 Gamma 0.54 0.59 0.66 Tau- a 0.27 0.30 0.33 c 0.77 0.79 0.83

13. Results

14. Results Risk estimation North Dakota, 2007 July 21 July 18 July 15 July 12 July 9 July 6 July 3 June 30 June 27 June 24 Flowering period Low risk Intermediate risk High risk Cavalier Towner Rolette Mean incidence 4% 8% 3%

15. Results SSR county prevalence and incidence, ND 2007 County Prevalence (%) Incidence (%) Ward Benson Rosseau Bottineau Benson Towner Cavalier Rollette 33 44 0 100 44 53 76 100 2 1 0 25 7 3 4 8

16. Results SSR county prevalence and incidence in 2008 Prevalence (%) Incidence (%) County (%) Fields Cavalier Ramsey Roseau Benson Bottineau Rolla Towner Ward 47 9 5 5 15 9 18 20 68 78 100 80 7 100 28 5 5 4 14 2 1 7 1 1

17. Results SSR county prevalence and incidence, ND 2009 County Prevalence (%) Incidence (%) Ward Benson Bottineau Towner Cavalier 13 25 50 60 47 1 2 1 2 3

18. Results Association between number of high-risk warnings and SSR prevalence SSR Prevalence (%) Number of high-risk warnings

19. Summary • Empirical model developed using weather data • Overall accuracy of model is approximately 75% • Prevalence of high risk warnings associated with higher SSR prevalence

20. Summary • Model improvement is needed • Areas were collaboration is sought: - Modeling leaf wetness duration - Use of Doppler radar data - Quantification of risk of apothecia formation

21. Acknowledgements • Curt Doetkott, ITS • NDSU scouts and county agents • USDA-ARS/Sclerotinia Initiative • North Dakota Canola Growers Association