Onion Growers Reminded To Watch For Downy Mildew

Washington State University is reminding onion growers to be on the lookout for Downy Mildew.  WSU’s Tim Waters said the cool wet spring we’ve seen across the Inland Northwest has allowed the mildew to develop and spread.

“It’s a water mold that’s similar to Late Blight in potatoes, so it doesn’t affect potatoes, but it does affect onions and the spores do move through the air fairly readily.  So, we’ve got some cooler conditions today and I think there’s some thunderstorms forecasted for certain areas, so those are defiantly conditions where a disease like that can move fairly readily.”

Waters said at this point, they have confirmed one field on the Columbia Basin with Downy Mildew, but that does not mean additional cases aren’t out there.  He said it’s important that growers scout their fields and if you come across something that could be Downy Mildew, to contact your local extension office as soon as possible.

Waters noted if you are in an area where Downy Mildew has been confirmed in a nearby field, you’ll want to apply preventative fungicides.

“Especially when conditions are conducive, so cooler, damper conditions are conducive conditions, particularly higher humidity.  We do get humidity when the pivot goes around, but really the humidity we get with rainy weather is more conducive for Downy Mildew development.”

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