Are all of the leaves like that? Discoloration-wise.

Not all of them, just a good handful. But spots of PM are present on 1/3 of them at least so far.

I cut off all the leaves with the dark brown/black coloration today.

Well, I take that back. It seems much more of the leaves are starting to get that light green colored spots as well.

It's starting to show on all three of my zucchini plants

The PM seems to be getting pretty bad on the underside of some of my plants as well.

As for the yellowing, I would pray there's enough Nitrogen out there. But I would personally say that this plant is salvageable!

http://www.organicgardening.com/learn-and-grow/powdery-mildew

Have faith :)

If it was any other cucurbit than zucchini, I might give up. But zucchini can be pelted with PM and just keep on kicking out fruit. Just remove the affected leaves, and treat the rest of the plant with a fungicide.

is that a cage? if so, why?

Kevin

I think I read about caging them last winter. The idea just stuck. I can't remember the specific reasons for doing it. It was on some SF gardening site. I think it was to save space

Don't get me wrong... I love cages. But not for zucchini or squash -- just too cumbersome of growth

But one of the reasons why PM propagates quickly is lack of air circulation. In the future, you may want to just let them flow and grow..

JMO

Kevin

This post was edited by woohooman on Fri, Jun 28, 13 at 20:10

I was thinking the same thing as Kevin. Squash are so prone to mildews that I would do away with anything that gathers all the leaves together like that.

I cut away the tomato cage. Hopefully the air helps then instead of making worse faster.

I have trouble every year with powdery mildew. This year I even had it on the butternut squash in the greenhouse. I read an article about using milk mixed at a rate of 1 part milk 3 parts water and it was more effective than synthetic fungicides. So I gave it a try. It worked. Three applications. First two three days apart, third one week later. gone. I did loose some leaves but the new leaves look ok. I'm going to do a weekly spray in the garden and see what happens this year. It is rumored to help with fungi on other plants too. Tomato blight, black sooty mildew. There are a lot of articles on the internet The one I read said most effective at 19% milk or higher for the mix and skim milk works as well as whole milk. If I can find the article I will post the url