I know this is a marijuana forum but I haven’t got any luck trying to figure out what this is. These are my tomato plants and clearly there is some issues going on. I don’t see any mites/alphids because I thought it might be spider mites but I don’t see any webbing or evidence. there are tiny black specks on leaves. I’ve treated leaves with SNS 203 but hasn’t seem to stop leaves from continually getting worse.
What kind of soil do you have them in and how much light are they getting per day? I currently have 3 tomato plants running and I have the best luck in a good weed soil like Ocean Forest or Happy Frog, but they are in the part of my yard that gets the most sun. Also even though I'd never recommend Miracle Gro for marijuana, I strongly recommend it for tomato plants. If you grow them from seed, wait until the plant is about 4 inches tall and give it a shot of MG. If you are buying starter plants, wait 24 hours after their transplant and give it to them. After the first feedings, I feed every couple months unless they are looking sickly. You might try giving that a shot now and see if they bounce back. Keep the soil damp, but not over watered. Good luck
Damages on pics coupled with the «tiny black specks on leaves» quoted from your post are signature of thrips infestation. Get some neem oil and spray at the end of day before dark. Repeat. Monitor infestation with yellow sticky traps. Read and learn about thrips life cycle; they lay eggs on leaves, pups end up in the soil for next stage of life than go back on plants to mate and lay eggs. I have found that covering the soil with a plastic lid (only good when using fabric pots, otherwise roots will lack of oxygen and rot) like this but on a bigger scale, break their life cycle and really help reduce the population. I also always had good results with Doctor Doom organic insecticides.