zucchini leaves bronze/yellow?

[Use Less]

A couple of big leaves (on giant zuke plants) are turning a bronze yellow everywhere but the outer inch or so. I went through a huge online cucurbit disease site w/o seeing a match. Might this be a nutrient deficit, or is it a disease? One zuke plant in the row had a few leaves w/downy mildew. This isn't that. (Those diseased leaves are gone & something fungicidal sprayed over all the cucurbits.) Thanks. Sue

[mekasmom]

How old are they? The leaves begin to die and the whole plant eventually dies after it is finished blooming and putting on vegs. Mine are starting to brown and die out now.

[Raven12]

This year was my first with zucchini and I quickly discovered that there are a multitude of diseases and pests that can destroy plants. Unfortunately, I had a difficult time finding a lot of info on the web. Good luck to you.