White stuff on Zucchini Leaves

marythompsonJuly 30, 2009

I'm a beginner suburban gardener with a small patch of tomatoes and zucchini in my backyard. I'm also a relatively new member of GardenWeb and this is my first posting to the forum.

I've had this white stuff appearing on the leaves of my zucchini plants. The zucchini's themselves seem fine, and the leaves don't seem to be harmed by it either. I didn't notice anything on the stalks or flowers. The white stuff is on a lot of the leaves but not all. It looks as if the plants are dusted with powder.

You can see 2 pictures here:


Anyone know what this is? Should I be worried about it? What should I do about it?

A lot of people around here have had tomato blight, but my tomatoes are fine. This is only on the zucchini which I started indoors from seeds myself.

Thanks for any help you can offer,


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Looks like it might be powdery mildew. You can spray it with a milk-water concoction to get rid of it.

    Bookmark   July 30, 2009 at 7:53PM
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Very cool. Thanks for the tip. I found info about using milk and water at the site below. I'll let you know how it goes.


Here is a link that might be useful: Milk and Water Mixture Article

    Bookmark   July 30, 2009 at 8:58PM
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I sprayed the milk/water mix on the leaves this afternoon. I'll post again in a few days after I see any results.

Thanks again,

    Bookmark   August 1, 2009 at 6:07PM
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Good link there, Mary. I use a solution of milk, baking soda, and a squirt of soap mixed in a hose end sprayer. I found some articles on just milk and water (like the one you posted), and some that said the use baking soda and soap. I figured I would try all of them together. It seems to work pretty good so far.

I have found it works best when you first begin noticing the powdery mildew. If you let it go too far, it pretty much takes over. Powdery mildew is a constant battle here in southeast VA.

Good luck with your zucchini!


    Bookmark   August 1, 2009 at 10:41PM
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marial1214(Z 6 PA)

My leaves are silvery too and so far I've been getting a couple squash per week which is plenty for us. Does powdery mildew kill the plants or stop them from producing?

    Bookmark   August 2, 2009 at 10:52AM
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The 'silver' on your leaves is a natural mottling and is not powdery mildew. PM is white, usually starts as round spots, and can be rubbed off. Here is a pic of my container zucchini taken moments ago...no powdery mildew...HTH

    Bookmark   August 2, 2009 at 11:26AM
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I had this same powder on my plants, they were producing zucchini, so I wasn't too concerned. Both of my plants were dead in 2 days. I know what to do in the future now, thanks for the info!

    Bookmark   July 14, 2011 at 11:28PM
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