Hello and thanx in advance for reading this newb post and giving any advice. I would be much obliged if someone can help me identify the blackish-brown blotches that started growing on these tomato seedlings a few days ago. According to research it is possibly "Early Blight", but there are no yellow halos around the blotches and, besides the blotching, the leaves are pretty dang green. At this point there are only one set of true leaves and the issue currently appears to be isolated to the cotyledons. There are also tiny yellowing tracks in the cotyledons that look like might be evidence of leaf-miner(?), but my camera stinks (no-macro) and the picture below is the closest-up shot I can get without the whole pic going to a blurr. Pretty sure my tomatoes are started too late again this season, but I'd still like to take them as far as I can without contaminating other plants. Not all of the seedlings in the same pot have the blotches, but the problem is happening in 2 of 5 varieties. Should I just cull the seedlings with the blotches, or is it best to dump the whole pot to avoid contamination? Should I even be concerned enough to cull? (I really hate pulling the babes.) Also, these seedlings were started outdoors on June 4th and emerged on June 12. Is their age based on sow date or emergence date?

Thanx for any help you can give me.

~KraZ