Turkington: Facilitating the Delivery of Practical Sclerotinia Stem Rot Risk Forecasts Based on Improved Assessment of Canola Petal Infestation
Date: April 2013
Term: 3 years
Status: Completed
Researcher(s): T. K. Turkington, Agriculture and Agri-Food Canada (AAFC), Lacombe AB, S. Strelkov, University of Alberta, Edmonton, AB, R. Kutcher, AAFC Melfort SK, B. Gossen, AAFC Saskatoon SK, D. McLaren, AAFC Brandon MB, K. Rashid, AAFC Morden MB
SaskCanola Investment: n/a
Total Project Cost: n/a
Funding Partners: n/a
Project Summary
Sclerotinia stem rot (Sclerotinia sclerotiorum) is one of the most important biotic stresses influencing long-term production and economic stability for canola producers. Researchers with the University of Alberta and Agriculture and Agri-Food Canada conducted a three-year study to develop a rapid, quantitative (q)PCR-based method for detection of S. sclerotiorum DNA on canola petals, which can be related to actual disease levels across the prairie canola growing region. The results indicate that this rapid, quantitative qPCR-based method was able to detect and quantify S. sclerotiorum DNA with a high level of sensitivity and specificity. This approach can provide a direct assessment of in-field disease pressure without the 3-5 day waiting period seen with the current agar plate petal test. If proven to work, this qPCR risk assessment tool will assist canola producers in making informed spray decisions as part of an IPM approach and reduce non-economic fungicide applications.
Sclerotinia stem rot (Sclerotinia sclerotiorum) is one of the most important biotic stresses influencing long-term production and economic stability for canola producers. Although producers and industry have access to existing risk assessment tools such as weather-based forecast maps, checklists, and petal testing, there has been limited widespread use of these tools. Development of a rapid assessment method for the detection of S. sclerotiorum on canola that is related to actual disease levels could represent an important advance in assessing stem rot risk in western Canada.
Researchers with the University of Alberta and Agriculture and Agri-Food Canada conducted a three-year study to develop a rapid, quantitative (q)PCR-based method for detection of Sclerotinia sclerotiorum DNA on canola petals, which can be related to actual disease levels across the prairie canola growing region. The objectives of the study were to develop a (q)PCR-based assay for S. sclerotiorum DNA, assess the relationship between the quantity of S. sclerotiorum DNA on flower petals and final stem rot levels in commercial fields and determine if pathogen detection and weather-based forecasts can be correlated with final disease. Researchers also wanted to determine if this method could be deployed in private seed testing labs with qPCR capabilities for commercial use.
For the study, researchers developed and refined sampling and real-time qPCR protocols to rapidly and quantitatively detect S. sclerotiorum DNA from canola petals. Assessments were performed to ensure no cross-reactivity with other microorganisms typically present on canola flowers. Early and late bloom samples were collected across Saskatchewan, Manitoba and Alberta from 87, 90, and 79 fields in 2010, 2011 and 2012 respectively. Fields were assessed for the incidence and severity of sclerotinia stem rot in August.
In approximately a third of the fields, the average percentage petal infestation with S. sclerotiorum was also assessed using an agar plate procedure (typically 200 petals plated per field and presence of S. sclerotiorum assessed after 3-5 days). Flower samples from approximately100 fields were collected across the prairies every year for 3 years and assessed using real-time qPCR analysis. Final disease incidence was recorded in the same fields and used to determine the relationship between qPCR results and stem rot disease incidence/severity.
Figure 1. Quantitative PCR estimations of petal infestation for canola fields around Edmonton, AB in 2013
Canola petals collected during the study are currently being analyzed to determine the relationship between qPCR results and final disease incidence, which will determine the potential for this assay to serve as a risk assessment tool. Regression analysis will be used to determine the relationship between qPCR quantification and final disease incidence and to set thresholds on which to base spray decisions on.
Overall, the study results showed that the rapid, quantitative qPCR-based method developed by researchers was able to detect and quantify S. sclerotiorum DNA with a high level of sensitivity and specificity. This approach can provide a direct assessment of in-field disease pressure without the 3-5 day waiting period seen with the current agar plate petal test. If proven to work, this qPCR risk assessment tool as part of an IPM approach will assist canola producers in making informed spray decisions and reduce non-economic fungicide applications.
Full Report PDF: n/a