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

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North Dakota canola producing areas DivideBurke RenvilleRoletteTowner Cavalier Mountrail Williams Ward McHenry Pierce Benson Ramsey WellsFoster Eddy Stutsman Griggs McLean Bottineau Rosseau Kittson Marshall Pennington Warren Red Lake Sheridan Nelson Fargo

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

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

 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 Weather data collection Model development

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

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

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

Percent concordance Percent discordance Somers’ D Gamma ParametersModel 1 Model 2 Model 3 Tau- a c Results y= (rain3)+0.07(rain4)-0.55(solar4)+0.53(rain5) -0.20(solar5)+0.38(rain6)

Results

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

Ward Benson Rosseau Bottineau Benson Towner Cavalier Rollette Prevalence (%)Incidence (%) County SSR county prevalence and incidence, ND 2007Results

Cavalier Ramsey Roseau Benson Bottineau Rolla Towner Ward Prevalence (%) Incidence (%) County (%) SSR county prevalence and incidence in Fields Results

Ward Benson Bottineau Towner Cavalier Prevalence (%)Incidence (%) County SSR county prevalence and incidence, ND 2009Results

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

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

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

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