Would anyone know what is causing my tomato seedlings to look like this? I think it must have something to do with my lawn clippings I thought I'll use as a mulch because before putting this down, the seedlings were looking fine. The lawn clipping were placed in an empty compost barrel for a few days before I thought to use the clippings as a mulch.
It sort of looks like you had piled the fresh clippings up against the stems. Most mulch but especially Green mulch should not be in contact with the plants -- leave a gap of at least 1-2 inches of bare soil because they "burn" the plants.
Now, in writing this, I realized I don't know specifically what that means -- it's what they always say. I do know green grass and hay will ferment and heat up -- enough to feel hot and steam, so maybe they do mean literally that the generated heat is enough to kill the plants (but they say something "burns" the plants when talking about putting chemical fertilizer too close, too). I think maybe the fermentation/microbial action could involve/infect the living tissue and break down the cell walls?
With grass clippings, it's a good idea to spread them out snd let them dry out on a paved surface before using them as mulch. Otherwise, they can also become a matted, slimy soggy stinky mess.
No the lawn hasn't been treated with any chemical. You make a lot of sense applestar, I did have the green mulch too close and it was warm to the touch. I'll move it away from the plants and see how they'll go.
It looks like bacterial spot. It has a "greasy" look to it.
Bacterial spot can come from infected seeds but also can come from other plant hosts. I would pull the plant and sanitize the area and not plant anything that is susceptible in that location.
