Prevent Tomato Late Blight Before It Starts

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Late blight of potato and tomato is caused by Phytophthora infestans, a devastating disease that contributed to the Irish potato famine of the 1840’s. Under cool and wet growing conditions, tomato and potato crops can be destroyed within days if left untreated.

Image of tomato with late blight

The time to prevent late blight is before any signs of it are visible. Prune and trellis plants to keep leaves off the ground and air circulating around your plants. Minimize leaf wetness via trellising and drip irrigation. Choose and start using a rotation of protectant fungicides: even some of the organic options such as copper, biofungicides, and peroxide-based fungicides are much better than leaving plants unsprayed. For more information about this and other crop management, call Cooperative Extension at 828-264-3061.