There has been a new development in the late blight situation this week. Recently late blight symptoms were observed on a couple of potato plants in Norfolk County. Industry specialists that were able to visit the infected plants are confident that the symptoms are late blight, but the field was top-killed before OMAFRA specialists were able to obtain a sample for laboratory testing.
Tomato growers should continue to scout for late blight symptoms in their fields, especially late varieties that still have substantial green foliage, and maintain a fungicide spray program that includes broad spectrum fungicides with activity against Phytophthora infestans. Consider the application of a late blight specific fungicide if risk is very high, such as when symptoms are observed in the field or nearby fields.
A summary of fungicides for late blight management in tomato is available here.
If you suspect late blight in your crop, please reach out to the appropriate OMAFRA specialist to confirm the diagnosis.
Tomato – Amanda Tracey (firstname.lastname@example.org, 519-350-7134)
Potato – Dennis Van Dyk (dennis.vandyk@ontario, 519-766-5337)