Powdery Mildew? Not sure!

opulidoMay 2, 2013


IâÂÂm a newbie gardener, this is my first year and IâÂÂd like to seek the advice or an explanation for the following potential issue I have with my zucchini plant. I noticed a white substance growing from the edge of the leaf towards the center of the leaf. IâÂÂve heard of powdery mildew, but from the pictures IâÂÂve seen online, PM is more of a spot-like formation. Anyway, IâÂÂm not sure what I have on my zucchinis��"or if itâÂÂs normal. IâÂÂve posted a picture, and IâÂÂd appreciate a possible explanation from some of the more experienced gardeners here.

Thanks in advance.

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I should also note that this plant went into the raised bed two days ago. Before transplant, this white stuff was not present; in fact, I have two other zucchini plants that are the same age but still in their pots without this white stuff present. The night I placed this particular plant into the soil I did water, but was relatively careful not to wet the leaves. Temperatures at night have been mid 50's.

    Bookmark   May 2, 2013 at 7:01PM
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jean001a(Portland OR 7b)

More likely environmental stress. Was it hardened off prior to planting? Even if you did, what were the weather conditions following planting -- you know, heat, light, wind, etc.

    Bookmark   May 2, 2013 at 7:45PM
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@ Jean001a:

It was hardened off. And as for the weather conditions following transplant: 90 degree weather and very strong winds (30-40 mph).

    Bookmark   May 2, 2013 at 8:32PM
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Powdery mildew on cucurbits where I'm at normally doesn't happen until the plants are adults and in the middle of summer when it's hot and humid.


    Bookmark   May 6, 2013 at 1:42AM
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Powdery Mildew is more a problem when the weather is hot and dry then when hot and humid.

Here is a link that might be useful: About Powdery Mildew

    Bookmark   May 6, 2013 at 7:18AM
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Thank you everybody for all the responses!

    Bookmark   May 6, 2013 at 7:13PM
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kimmsr: I'm sure UC Davis knows what they're talking about and PM can affect some veggies without humidity-- much like to my snow peas just within the last month. But I deal with it EVERY year and from my experience with cucurbits, it doesn't get bad until it gets humid along with the heat of summer.


    Bookmark   May 7, 2013 at 1:06AM
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