Fungicide And Insecticide Tank Mixes
Growers in southern Alberta and southwestern Saskatchewan often spray for cabbage seedpod weevil at 20% flower. This is also an ideal time for sclerotinia spraying if conditions warrant a spray.
Canada's crop protection rules allow growers to tank mix two products as long as they are both registered for the crop in question and at the timing and rates used. But these rules do not ensure these products can be mixed without problems in the tank (they may create a gummy mixture that ruins the sprayer) or without antagonizing each other (both products becoming less effective.) Growers are advised to ask the retailer or the crop protection company before trying a tank mix for the first time.
Of the six products registered for sclerotinia management in canola, only one has a registered tank mix with insecticide. That is Astound with Matador. Serenade, which has a biological active ingredient, explicitly says "Do not tank mix with pesticides."
The key with any tank mix is to make sure both products are in fact needed. It may be convenient to tank mix because you're going over the crop anyway, but applying an unnecessary product adds to the cost without providing a benefit to justify this cost. It could also cause future problems by reducing levels of beneficial organisms which regulate potential pests.
Source: Canola Council of Canada