Leaf curling alone is a physiological condition caused by stress; it's common in stressed plants, including young plants which don't have the root system to support all their foliage yet, or in times of unusually bright sunlight. If you get it by itself, look to see what may have stressed the plant recently; often it's nothing to worry about. The wilting, dead green leaves symptom resembles bacterial wilt, but that's pretty rare in your neck of the woods, and tends to take the whole plant down very rapidly. Stem borers can sometimes do it; look for little holes in the affected stems. Look for any damage to the stem, in fact. With the yellowing and necrosis -- it's hard to see in that small a photo, but it looks like the dark lesions are following the veins. That's diagnostic of a toxin of some kind -- no virus I know of does that in tomato, no bacterium or fungus is that specific, and no deficiency kills the veins before the interveinal spaces. I've seen a symptom almost identical to that in a case of alcohol poisoning (someone had a cocktail party in a library foyer and apparently the drinks weren't very good, as the potted plants looked pretty rough afterward). It was an unusual enough symptom that it became a teaching example. Toxins can come from outside or from the soil. Pyola is perfectly safe for tomatoes, and the heat wasn't excessive, but make sure the dilution was correct, as too high a concentration can burn leaves much like that. Spray damage can also cause wilted and dead green leaves. If you can sacrifice a plant that's badly affected, dig it up to look at the roots, see whether it has lots of crisp, white, fine roots, not dark or knobby ones. Shave away the skin at the soil line to look for discolorations in the woody stem underneath; cut open wilted green shoots to check for hollow centers from stem borers; and finally split open the main stem to see whether it's hollow or discolored inside. I don't expect much except maybe root symptoms, but you really never know. My personal guess is soil toxicity, especially given that the lower and terminal leaves are the worst affected by the yellowing and dying, and some things take a while to build up in the leaves enough to kill them. One important thing to note is that not all toxins are synthetic chemicals -- an excess of certain minerals or nutrients can poison a plant. pH affects root uptake of anything enormously, especially minerals, but it can have its own effect as well. You may need a soil test -- call your Agriculture Department, Cooperative Extension, or U of O to find an affordable lab. I don't see your symptoms in any of the common nutrient toxicity listings, though, which means it could be something chemical, and there is no general panel for that. Down here in California I'd send it to Sacramento's Plant Diagnostics lab or the extension pathologist at U. C. Davis, but I don't know what pathologists you have at your disposal. This is certainly not a cut-and-dried common disease problem, and even a specialist is going to need some lab work to figure it out, I suspect. I wish I had more answers for you, sorry. --Alison

Same thread at link. Also, additional images and several responses. Here is a link that might be useful: other thread

It looks like water stress and sounds like WAY too much water. My tomatoes are in the ground and I don't water until they are dry a full finger-depth down (a little over 2"). Since your plant is in a container it is probably harboring lots of water at the bottom. Try backing off the watering to just once every couple of days. I bet that helps a lot.

Yes, the pot looks small and the plant looks underfed. You are giving it only about a quarter of its nutrient needs: Citrus Focus instructions say "Add 10ml of Citrus Focus in every litre of clean water, weekly. If leaves are pale or yellow, increase frequency of application."