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Are my butternut squash plants diseased? New to gardening..

I posted 3 pics of 3 butternut squash plants. Some have spotted white leaves, some have nearly all white leaves and the 3rd has a combo of both. I live in Southern CA. Are these squash plants diseased? If so, are they able to be saved or should they be dug up and replaced with new healthy plants?

This is my first ever garden! Thank you for advice.

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Senior Member
Posts: 230
Joined: Mon Mar 19, 2007 6:52 am
Location: North Georgia

Hi there! I believe this is a case of Powdery Mildew, a fungal infection. From what I have read, it is common when temperatures and humidity are both high, and late planted squash are especially more prone to fungal infections of this type.

You can apply garden quality sulfer, or a good sulfer based fungicide or cholorothalonil, each of these as per label instructions for whatever kind you decide to use.
Another option you can use is a paraffinic oil [a horticultural oil] with baking soda [3 tablespoons of oil and 3 tablespoons of baking soda into a gallon of water] to spray on the plants.

Either way, if this is indeed Powdery Mildew, a good fungicide treatment should clear up the problem, and it probably wouldn't hurt to repeat the treatment in a couple of weeks. Make sure to get the soil around the plant as well as the plant itself with the spray, as the fungus can lurk in the mulch around your plants when it is moist.

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Posts: 168
Joined: Wed Jun 13, 2007 12:12 pm
Location: El Dorado, CA.

thanks rodger,..thats good to know. I have been seeing a bit of that myself.... :cry:

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