Fusarium Wilt

[Christa B.]

One of my tomato plants started wilting heavily on one side. The leaves didn't turn yellow, they were just extremely wilted so I cut that section of the plant off. several days later more of the plant began to wilt the same way, green wilted leaves. I pulled the plant up, just in case it was diseased. I wish that I would have taken a photo before I pulled it out but I didn't think to do it. After I pulled it up, I did cut the stem open and I took some photos. What do you guys think? Is it fusarium wilt? I read that fusarium is most often a southern plant disease. I live in southwest, Ohio, zone 6a. Some would say my winters are cold, others would say they aren't that bad. I would say that I have a middle of the road kind of climate, not southern and not really northern either.
I should also mention that I have woods growing around my yard and there are several black walnut trees in there but I have never found any roots in my garden so I doubt that juglone from the walnut trees is the issue, I would assume that the entire plant would wilt in that case. This was a plant that was very close to having ripe tomatoes on it. Thanks for any help! Besides occasionally reading about it on the internet, I have no experience with fusarium. I did read that the leaves turn yellow with fusarium, is that always true? That didn't happen to mine.