Late blight has been confirmed on tomatoes in Wayne and Ashland counties this week. We also found downy mildew in basil, cucumber and melons in our sentinel plot in Fremont, OH.
Downy mildew is assumed to be widespread on cucumbers and melons in Ohio, but we have not yet found downy mildew on squash or pumpkins. The late blight and downy mildew pathogens are related and all are favored by moderate temperatures, rain, high humidity and cloudy skies.
Tomatoes, potatoes, cucurbits and basil should be scouted regularly and treated with protectant fungicides. Management recommendations have been posted this summer for all of these diseases.
See u.osu.edu/miller.769 for management recommendations.
Sally A. Miller