Leaf Damage I.D.

[SuntannedSwede]

Hello,

I have noticed that a fair number of my tomato plants are showing the same signs of leaf damage, all on the lowest branches. I'm not too worried about it, seeing as the newest growth is fine, but I'm just trying to figure out what may have happened to them so I can avoid it next year.

I will post some pictures here, you will notice that they are quite large to be in solo cups, they were started way too early.

Does this look like a disease issue? I tried to do some searches here but was never really sure of what it could be. They were started in Miracle Gro Potting Mix so would the fertilizer added to the soil be enough to hurt the leaves? They are dry and brittle to the touch, and the branches that are really bad (all leaves heavily damaged) break off readily.

Thank you for your time