Have you had alot of rain lately like most of us. If so then the bacterial diseases are running wild. Your's looks like Bacterial Speck/Spot is a real possibility. There are all sorts of recommended sprays but most are only minimally effective with the bacterial diseases IME so I only use either of them in extreme cases. But you can try them if you wish.

Hydrogen peroxide 1 part to 20 parts water or Chlorox bleach 1 part to 20 parts water. They need to be lightly misted on, not drenched, need to be sprayed in the early AM not in the direct sun or the heat of the day, and they will cause additional leaves that look normal to the eye to die as well as they kill the bacteria.

Main thing is to strip all the affected leaves off the plants, bag and dispose of them and keep removing the leaves as they appear. As the rain stops (no overhead watering) and the weather warms and the plants dry out it will decrease on its own if you keep ahead of it.

Hope this helps.

Dave

I wouldn't spray with bleach unless you are sure there will be an uninterrupted set of dry weather days in the forecast, or it could backfire. I generally don't like spraying bleach on live plants, though others go on about how much they attribute improvement to it. I'd rather be aggressive with pruning of the worst petioles daily without being a butcher.

Can't be sure what the disease is here but agree, spot/speck might be more likely than Septoria. I like the peroxide spray suggestion. 1 to 40 dilution if fresh bought H2O2 is what I used this season, and a very fine spray. digdirt's plan is about as comprehensive advice as could be offered. Copper might be another possibility. I just mention it as a wetter weather thing to try, to be complete, but honestly not much of a fan of it, either. I probably would use it on my other 3 plants though.

Not sure that pulling the plant will help the your overall yield, doesn't seem like a gamble at this point I'd take. I definitely would be super careful not have any overlapping suspicious leaves near the plants that look healthy, since drip contact is a surefire way to infect. Be very careful when irrigating/splashing the raised bed too.
PC

yeah, we have had quite a few periods of rain in NJ, several heavy days in a row, a brief respite then back to rain again

Should I just remove that plant or if i keep removing the leaves as I see them and let it dry out it could be ok?

These are pretty personal decisions. I would only remove it at this point if the tomato fruits have disease on them too because I would be hoping to save a bird-in-hand.

Imagine the life of a commercial farmer dealing with these questions for 1000's of plants when part of the field gets infected. How aggressive will it spread? We're not positive which disease it is (but make no mistake, it's one of them).

Thoughts like, if you pull it now and tomorrow spots start showing up on other plants who can you blame LOL... Or, on the other hand, if you don't pull it and are able to control it and get most of the tomatoes from all 4. The only thing for sure at this point is if you pull it you lose perhaps 25%. Seems a stiff penalty to me. Size up the situation as best as you can YMMV.

I've got my worst leaf mold plant that yielded the weight for 3 other plants and the tomatoes are great. In my case the best producer was the one that get sickest, probably because it was stressed from all its production more than anything else. And I've got a leaf mold problem that it made a bit worse for sure but I lucked out overall.

I'd be preventative with copper spray for your three good plants and keep my fingers crossed. If rain gives a chance to hit the sick leaves with peroxide, I'd be all over that trying to save my maters. If I failed spectacularly I'd pick myself up and dust off and convince myself it was a learning experience. If you reach a point where the plant is obviously no longer going to be productive, nothing more is lost by pulling it then, which you decide crossing that bridge. At this point the going assumption is you have developing tomatoes to save, right?
PC

<Should I just remove that plant or if i keep removing the leaves as I see them and let it dry out it could be ok?>

Your choice but what we are both saying is there is nothing gained by removing it and it might recover.

Dave

PC and I were typing at the same time I guess. :)

Unfortunately the choice was taken from me. Went to look at the garden after the storms in NJ yesterday and the other tomatoes were doing well but the mortgage lifter had collapsed into itself and most of the leaves were dead :(

If one plant had to go at least it was that one :( So sorry to hear what happened, most reviews on Mortgage Lifter are that it tastes so good.

Like digdirt suggested initially for the diseased prunings, carefully removing the entire dead plant material into plastic bags for disposal now ... the sooner the better, if you haven't already done it. It's not the kind of thing to have around as mulch. Best of luck with the other three; hope they are nice varieties too!
PC

It is kind of weird you posted this because of my experience last year. I planted a Mortgage Lifter last year because of the taste reports. It was the only tomato plant (11 total plants) that did poorly because of disease. Maybe just coincidental....