Late Blight Update – July 17th, 2025

Late blight has been confirmed on potatoes in Dufferin County. The identified area was small but risk of late blight should be considered high.

Samples have been submitted for strain ID and results will be shared when available. The late blight strain the last few years has been US-23 which is susceptible to Ridomil.

If you haven’t already applied a late blight specific fungicide, you should do so now. Ensure new growth remains protected. Visit the Ontario Crop Protection Hub to view registered late blight specific products on potatoes and tomatoes.

Review the potato late blight entry in Ontario CropIPM to refresh yourself on what late blight infection looks like. The tomato late blight entry can be found at this link.