or maybe something else...

My tomatos seemed to be doing pretty well until yesterday.

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but today I noted spots on the lower leaves. Perhaps I overlooked them since I did not inspect them closely in the past few days, but this seems to be pretty recent (or early) symptoms of something.

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specs on my setup:

(2) 4'x 2.5' containers, made from 2x12 untreated hemlock

All bagged planting soil mixed with bagged landscape topsoil and bagged arena sand.

grass removed on site to a 4 in depth and weedstop fabric doubled below raised beds. fabric was cut in an "x" below the site of each tomato plant to allow deep root to pass through.

Instead of mulch, I used weed stop fabric stapled to the top of the bed and cut out minimum fabric around plants.

Soaker hose operated by timer was enclosed under the fabric to avoid wetting leaves during watering.

Due to high sand content in the mix, and glacial morain (really good) drainage under the beds, I found 2 hours daily did not overwater.

No signs of BER or deficiency based problems. Electronic hydrometer and Ph tester used weekly.

No weed growth in container since there is no room.

Potential problems:

The 450 acres to the south and east of me have been regraded and massive construction and contract landscaping have been going on for 2 years now, and is expected to continue for 2 more years. (1700 housing units)

This fills the air with dust and windblown particulate and seeds to such an extent that my air cleaner filters in the house have to be replaced frequently. Ornamental plants (many non native) by the thousands have been planted.