Help - can someone ID this foliage disorder? (pics)

[Eric02476]

This progressive brownish discoloration started appearing on lower leaves about 2 weeks after setting out my seedlings in EarthBoxes. It is spreading to upper leaves and also appears to be spreading plant to plant -- or at least it's affecting the other plant in the same EB and the plants in the adjacent EB (1 foot away).

The discoloration gets darker as time passes, and the leaves on the oldest affected leaves are now curling. The discoloration is on both sides of the leaves. Suspecting a fungal disease, I did start spraying with Daconil shortly after the first symptoms appeared. It hasn't seemed to stop the spread, although I was using 2-3 year old Daconil (I just bought new stuff today).

The affected plants are now about 10" and are still producing new growth, but I don't know if they can outrun this. I am very concerned.

I have consulted many online tomato problem solver photo sites and cannot recognize this particular pattern. I don't know if this is a disease or a physiologic problem. We've had some temperature fluctuations and some cool, wet weather recently.

Does anyone recognize this? (See photos attached). The photos show an earlier stage and a later stage - the later stage shows the leaf curl. I'm in Zone 6A, eastern Mass.