Today I was Asked,

 Today I was asked,

How do you deal with the white mould on the leaves that makes it way down the stems? I've given up on zucchini because of it? And what causes it? Thanks.

And I responded,

Answering the meaning of life might be easier but here goes.

How do you deal with the white mould on the leaves that makes it way down the stems?

There two organic ways I can think of, 1st is using something like Copper Oxychloride. Just follow the instructions on the packet. https://www.searlesgardening.com.au/.../SCX200--searles...

2nd is milk spray and this video shows this very well. https://youtu.be/4LOHItzP28w

Another way I'm trying this year, and so far with good results, is to buy mildew and virus-resistant seed. The variety I'm trying is from "Lambley Nursery" called Nitro F1. https://lambley.com.au/.../zucchini-nitro-f1-cucurbita-pepo

Also, remove the older leaves as soon as you notice any sign of powdery mildew forming and bin the leaf/leaves.

What causes it?

Humidity and underwatering and it is just in that family of plants that are really susceptible to powdery mildew.

Hope this helps.