As we come to the start of July and look out into our canola fields, we are seeing beautiful cabbaging canola that is starting to bolt. One of the big questions we always have from our growers is whether or not it is worth spraying canola for sclerotinia. As growers are facing tight margins and pricey costs of application, the question always is, “Will we see a ROI from a sclerotinia application?”
Forecasting Tools Available to Growers
Growers have some great tools that can help them forecast the development of sclerotinia in their area. Some of these tools include: Risk assessment maps put out for the prairie provinces that are available on the Canola Council Website, a checklist based on environmental conditions, and our personal favourite, petal testing. There is no method that is 100% accurate, but these different tools can help us make an educated decision.
Conditions Favorable for Sclerotinia
For sclerotia germination, spore production and spore growth, we need to have favourable environmental factors such as rainfall and soil moisture. Summers with wet, damp and humid conditions are the perfect weather for us to see high amounts of sclerotinia in the canola. Another condition that is favorable for sclerotinia is a dense crop canopy. When we have these dense heavy canopies, we see a lack of sunlight able to penetrate through and evaporate the moisture under the canopy.
Ideal Bloom Staging
When we are looking at doing a fungicide application for sclerotinia, timing is critical. For application timing, we are looking at between 20%-50% flower, and prior to significant petal drop. Fungicide application needs to begin when it is at 20% flower – meaning, we see 15 open f lowers on the main stem. When the number of open flowers on the main stem exceed 20, we are at 50% flower, and this is a sign that our application window is closing for fungicide. Canola fields will be at it most yellow during this stage.
For more question on Sclerotinia and fungicide options, please contact your local Synergy AG agronomist.