Potatoes in Canada

Crop Watch News Diseases
Late blight symptoms observed in Delhi, Ont.


August 26, 2020
By Stephanie Gordon


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Late blight symptoms on a potato plant. Photo courtesy of Eugenia Banks.

Late blight symptoms were observed on a couple of potato plants near Delhi, Ont. a couple days ago, according to the Ontario’s Ministry of Agriculture, Food and Rural Affairs (OMAFRA) vegetable crop report on August 26.

Industry specialists that were able to visit the infected plants are confident that the symptoms are late blight, but the field was sprayed before OMAFRA specialists were able to obtain a sample for laboratory testing.

According to OMAFRA’s vegetable team, 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. Growers are asked to 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.

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A summary of fungicides for late blight management is available here.

For more, Ontario’s potato specialist Eugenia Banks shares early summer, mid-summer, and late summer practices to protect growers against late blight in their potato fields.