I also grow in Earth Boxes. This year due to excessive rain my tomatoes developed fusarium wilt which is caused by a fungus which can be airborne according to what the farmers extension told me. My plants were all started from seed by me, and were very healthy, after one got the fungus it started to spread to every other tomato plant. I sprayed with Serenade and Draconil and the first spraying saved all but the original plant.

I believe the farmers extension either mis-diagnosed your problem or is mis-informed. According to several university agricultural departments (and Carolyn) Fusarium Wilt enters the plant through the roots or is seed borne. It spreads to other plants through the soil so it shouldn't jump between Earthboxes. Serenade and Daconil and not effective against it. You must have had some foliar fungal disease.
I was interested in knowing if others had obtained diseased seed.
Thanks for you input.

well, hubby was one who went and asked them and he just told me it was a fungus and also a bacteria - guess I just assumed it was fusarium wilt- but apparently there's a ton of different types of fungus & bacteria looking at some of the other websites!- whatever it was the Daconil and Serenade dleared it right up. Never had this problem any other year and there was excessive rain this year.