Downy Mildew Update – June 29th, 2012

To date, there are no confirmed cases of cucurbit downy mildew in Ontario pickling cucumber fields.  While the current hot, dry conditions are less conducive to the spread of this disease, there is no such thing as “zero” risk.  The downy mildew season in the Southern US remains quite active, with a recent report out of Pennsylvania.

Follow a 7-day preventative fungicide program, using only recommended downy mildew fungicides.  While it is tempting to lengthen the spray interval, or even skip a spray, remember that at the pre-harvest stage, we have the most to lose if downy mildew does become established in the crop.  Downy mildew is far less aggressive in fields which have received regular fungicide applications.

For more information on the 2012 Downy Mildew Control Strategy for Cucumbers, visit

Downy Mildew on Cucumber
Early symptoms of downy mildew infection on the upper leaf surface of a cucumber leaf.

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