Potatoes in Canada

News Diseases
High numbers of late blight spores reported in Norfolk County, Ont.


July 22, 2019
By Stephanie Gordon


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High numbers of late blight spores were found in the filters of two spore traps placed near Delhi, Ont., according to Ontario potato specialist Eugenia Banks.

The Delhi area recently received enough rain to create favourable conditions for late blight disease development.

This news comes after late blight was found on potatoes in Wisconsin earlier last week. At the time of the Wisconsin announcement, spore traps in Ontario had detected only low levels of late blight DNA. Spore traps for detecting late blight are placed in Shelburne, Alliston, and Simcoe-Delhi areas.

Banks urges growers in the Delhi area to keep the crop protected, especially new growth. “It’s the best way to reduce the risk of outbreaks,” Banks added.

In Norfolk County, the larger division where Delhi is located, some early planted fields are being topkilled. Banks says tank mixing Reglone with a copper hydroxide (for example, Parasol) should ensure that spores landing on stem areas are killed thoroughly. Spores that are not killed by Reglone will be killed by the copper hydroxide product. However, Banks adds that the Parasol label states that the product should not be applied within two days of harvest.