The worst possible scenario is that it is the early signs of Late Blight which usually hits the top third of the plant first. I have seen it a couple of times in early summer or late spring and it looks similar to what you are showing in those pictures. Keep a close eye out for any signs of a light colored fuzzy looking mold showing up under those kind of spots or lesions on the stems. It probably isn't Late Blight but I never rule it out too early because it can hit any time of the year down here. A friend of mine lost his whole tomato patch to it one year in early June.
I don't think that is gray mold which usually starts in the shady lower portion of the plant first and moves up. It could even be spray damage or some kind of wind damage from all the high winds we have been having lately. It doesn't look like TSWV either but if the plant stops growing and further spots show up I would pull it.
I think using the copper spray is wise and if it is one of those pesky spot or speck diseases it could very well cure the problem. Good luck.
Bill
|