Objective
This project was intended to determine if recent Sclerotinia insensitivity to fungicide could be related to fungicide resistance or inadequate spray coverage. This project’s objectives were to evaluate the efficacy of Acapela (group 11), Miravis Bold (group 7), and Proline Gold (group 3,7) on controlling Sclerotinia stem rot in canola and to evaluate the effect of increasing water volume from 60 to 120 l/ac has on fungicidal control of Sclerotinia. Also to document the effect of water volume on the coverage and canopy penetration at the top of canopy, first flower level and 5 inches below the 1st flower level using water sensitive paper.
Project Description
A trial was established near Yorkton to determine if poor control of Sclerotinia in canola could be attributed to fungicide resistance or inadequate spray coverage. The fungicides, Acapela (group 11), Miravis Bold (group 7), and Proline Gold (group 3,7) were compared at water volumes of 60 l/ac and 120 l/ac. The crop was a little thin allowing excellent penetration of fungicide into the crop canopy, particularly when the higher water volume (120 l/ac) was used. Unfortunately, Sclerotinia pressure was relatively low and the strong presence of Verticillium wilt made disease ratings for Sclerotinia challenging. While disease reduction and increased yield was associated with the application of fungicide, no significant differences between fungicides or water volumes could be detected. Sclerotia taken from the farm, the year prior to this study, will be part of the western Canada report on “Sclerotinia sensitivity to fungicide”. These results will be presented at Canola week in December 2026.
Grower Benefits
Spray coverage declined with canopy penetration as expected. However, coverage was still very good at depth (5 inches below 1st flower) due to a relatively thin canopy. Increasing water volume from 60 to 120 l/ac substantially increased coverage. Coverage at the deepest level at 120 l/ac was far greater than coverage at the canopy top with 60 l/ac. There was some evidence to suggest Sclerotinia infection was decreased and yield was increased by the application of fungicide, but differences were largely insignificant. While there was a heavy presence of Verticillium wilt, Sclerotinia pressure was low. There was no evidence to suggest control of Sclerotinia differed between fungicides or water volumes. Prior to the initiation of this trial, Sclerotia from our research farm were sent to Lone Buchwaldt (Ag Canada, Saskatoon) to be part of a Western Canada survey. Samples from 56 fields within Saskatchewan were shipped to Germany for testing along with isolates from Alberta and Manitoba. In collaboration with Chris Manchur with the Canola Council, a summary of sensitivity testing of all 400 isolates against six fungicides will be shared at “Canola Week” in December 2026.
