I'd like to know what is happening to the stems and some veins of some of my rainbow chard. Everything written that I found was about foliar diseases or pests that eat the leaves. This is not that; the plants look otherwise fine; they are giant and healthy. And not all of them have this, mostly just the yellow ones but some of the red ones as well. These look kind of evenly spaced lesions, they are bumpy with little crater-like indentations. I ate some of the other chard but avoided eating these since I was not sure if it could be fungal.