I'm currently fighting this with a zucchini plant. I'm trying to do it organically by making sure it has plenty what it needs. It's having issues even putting out female buds...only have had 2, and one failed to pollinate.

I have the same experience, after the first few fruit the plants get brown leaves and soon die. This is the story on beans, tomatoes, peppers and cucumbers. It's very frustrating since I never had this problem on Maui and on the mainland. I just started putting copper sulfate in the spray mix I use of baking soda, dish detergent, and canola oil. I know this is a big problem for commercial growers, I know one and he has to use commercial fungicides heavily on his crop of Thai Basil.

dish soap is NOT equivalent to horticultural soap ...as it can have certain harmful chems in it ...

kimmer in the garden clinic is the spert on that topic ...

i understand you live in paradise.. but you are still in the northern hemisphere.. i ask ...

is growing in winter.. different than in summer.. with the reduced sunlight intensity??? .. perhaps choosing certain crops for certain seasons.. might help ...

and..mildews thrive in dark humid nights... NEVER allow your plants to go into dark wet ... IF you can avoid such .... which you might not ....

your bottom line.. is basically .. if the local pros can barely beat it... i doubt there is anything you are going to be able to do about it .... two thumbs up for consulting local peeps ....

ken

My basil has been doing great for a while now...interesting. I ended up having to pull out the zucchini. Hopefully the cucumbers I planted don't merry the same fate...

Try adding a little Apple Cider Vinegar to your home brew fungicide.
Always spot test a leaf or two.