Do I need to fertilize?? Let the soil dry out for a few days? Or treat them for blight?

The first two definitely, especially the part about cutting back on watering. That is the main source of the problems IMO - overwatering.

The fungicide is your choice. I don't see any symptoms on the pics, just one leaf that's a maybe.

Unless you want to start a regular weekly fungicide spray program from day of plant out you can't prevent Early Blight, just slow it down. Otherwise I'd just remove the leaf and keep an eye on it.

Dave

What he said.

Are plants from "Big Box Stores" really hardened off when you buy them? The stores do not look like my garden. I would buy them several days before I wanted to plant them, then go through a hardening-off procedure before I transplanted them to my garden.

I use a 3-4 day process for moving my tomatoes and peppers from my greenhouse to my garden. I have an outside shelter made from old storm and patio doors and screens, that reduces the wind velocity and sun exposure by 1/3 to 1/4 where my plants spend several days before they are introduced to the cruel outside world.

Both the Lowe's and the WM here keep their tomato and veggie seedlings outdoors. At the Lowe's, the plants are on the side of the building which faces ESE, so they get sun at midday and all afternoon. WM's plants are on the south side of the building, so they get sun all day.

These are mostly Bonnie Plants seedlings. Where Bonnie keeps them before delivery, I have no idea, but I know that Bonnie (and, I think, also Metrolina Greenhouses at Lowe's) send staff to the stores to water the plants. The store staff don't handle any plant care, and I'm sure they don't move seedlings around to harden them off.

I don't know if the seedling display shelves have wheels or not, but Lowe's outdoor display tables in the same area are simply metal mesh panels set on cinderblock legs. If there are wheels on the seedling shelving, I suppose Lowe's or WM might bring those displays into the fenced garden area at night to prevent theft. But there certainly isn't space indoors (particularly during the day) for plants being hardened off.

We have a HD as well; I think I've been there a whole 3 times over the years, but as it happens, I was there last month. The tomato seedlings were in a fenced area near the outdoor check-out area; Google's satellite view shows that area with some sort of roof, maybe translucent fiberglass panels.