https://ag.umass.edu/vegetable/fact-sheets/cercospora-leaf-spot-of-swiss-chard-beets-spinach

Looks like the beginnings of leaf spot. Keep the garden cleaned up well to keep potential sources of infection from the location and use a copper fungicide.

Rodney

That looks like a pretty old leaf anyway, so no I wouldn't eat it. But not because of the leaf spot. Because of the age. Personally I wouldn't use copper on it. I'd just grow it fast, clean up dead stuff and eat it young. That's a very small leaf for its stage of maturity so I suspect your chard could do with a lot more water.

It actually is a fresh leaf, but other leaves that have leaf spot, would you/could you still eat them or you discard them?

"Fresh" is quite different from old or new leaves. Fresh only means recently picked.....old or new leaves refer to how long they have been present on the plant. With chard or kale, you want to be harvesting the youngest/newest leaves, not the older tough ones.

And no, it won't hurt you to eat the spotted leaves.

Does one even eat chard raw? I never have :-) If sauteed or creamed or used in other dishes, the spots will be unnoticeable. And even if used raw in salad, etc, wouldn't the pieces be small enough that any spots woud be invisible? Or just use a creamy dressing to disguise :-)

Swiss chard is an "always" in our evening salad. We only eat the greens raw. Though when the stems get really large, we chop them up and use them in soups instead of celery. We never cook the leaves. If I'm going to cook a green, I'll cook collards.

I eat it cooked like spinach. It's a winter veg for me and I tend not to fancy salads in winter. If I do I eat salad it's mixed lettuce, rocket, etc. Not the giant, thick leaves of chard. In spring I might add chard seedlings to a salad.

I eat salads in the winter. My chard leaves are no larger than Romaine this time of year. They get pretty big in the summer, but that just means big salads!