Late Blight Update – July 24th 2025

Late blight strain ID testing has confirmed the strain found on potatoes was US-23. This is the same strain that has been found the last few years in Ontario and the important note is that it is still sensitive to Ridomil.

Late blight has not been reported in any other commercial potato or tomato field in Ontario since the initial finding last week.

Cornell Extension has reported late blight confirmations on potatoes and tomatoes in Western New York. With forecasted thunder storms over the next few days, late blight risk remains high.