With canola beginning to flower, it is time to assess risk for sclerotinia stem rot infection and 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, and 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.