Hey everyone, I'm sure there's a million threads describing scenarios like this, but after looking through quite a few, none really quite seemed to match.

In a nutshell, one well established German Johnson plant started to yellow at the end of the lower leaves...didn't look dead at all, in fact they looked entirely normal other than the color (think sunflower yellow, maybe a touch paler). The yellowing then seems to spread up each leaf towards the stem, then to different areas on the plant, without splotches..just systematic yellowing. Interestingly, it was almost uniformly the "sucker" leaf sets at first, but it eventually spread elsewhere.

I was hoping it was just the plant, and I yanked it out, but I have four GJs planted right together and it seems to have begun on a second plant now, and maybe a third. Plants seem otherwise healthy, but the one plant had 2/3 of its leaves starting to yellow when I pulled it.

The plants have been there for a 40 or 50 days now and are several feet tall, so that makes me think its not a pH problem (though I haven't tested the soil), but it could be nutrients, virus, or maybe fungal. Thoughts and ideas?

I've got about 35 tomato plants, and would prefer not to lose a bunch of them...