Potatoes in Canada

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New mefenoxam-resistant strain of late blight found

A new strain of late blight, US-25, has been identified in New York state, according to Eugenia Banks’ latest potato update.


August 30, 2018
By Potatoes in Canada

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While this strain of late blight has only been found in tomatoes so far, under a laboratory setting it has infected potatoes. Christine Smart at Cornell University has been keeping potato pathologists informed of this new type which is now known to be mefenoxam resistant and of the A2 mating type.

So far this year, the US-23 strain has the been the most prominent strain of late blight found. Incidents have been reported in Ontario, Michigan, Illinois and Wisconsin. US-23 is still susceptible to mefenoxam-based fungicide, like Ridomil.