Late-seeded and re-seeded canola fields are beginning to flower. These fields should now be assessed for risk to sclerotinia stem rot infection to determine if a fungicide application will be economical. Remember, many factors affect the risk of infection including:
- Heaviness of the crop canopy
- Amount of moisture received in the two weeks prior to flowering and potential for further rainfall
- Years since last host crop
- Disease incidence in the past
- Presence of apothecia in neighboring fields
Thin stands which result in a light, open canopy will likely help lower risk in a number of locations this year. However, regular precipitation and high humidity at early flowering can still lead to significant disease development in thin stands, especially if plants begin to lodge.
The link https://canola-council.merchantsecure.com/canola_resources/product11.aspx is a “Canola Disease Scouting and Risk Assessment Card” which can help with risk assessment: This card will help determine if fungicide applications are warranted, particularly where yield potential is reduced by late maturity or low plant numbers.
Alberta Canola Producers Commission has an audio discussion on scouting for sclerotinia and making fungicide decisions with Dr. Kelly Turkington, Agriculture and Agri-Food Canada at the following link: http://www.canola.ab.ca/.