Jim Carlock wrote:
James wrote:

Try not growing the same plants in the same spot year after year.


Tomatoes are supposed to be the exception to that rule.


They are not. I've found tomatoes to be exceptionally susceptible to
soil borne diseases and have had to ensure they are rotated and the soil
solarized in between (as some wilts can remain in the soil up to 8 years).

They also must avoid former potato areas which are susceptible to many
of the same diseases. If there were potato scraps or diseased tomato
plants in the compost, the disease will stay around. (I never compost
tomato or potatoes or any part of their plant).

From the OP, it sounds like a wilt disease (or early blight). If the
plants are grown too close together, the disease also spreads very
quickly from plant to plant.

I've solved most of the problem by planting my tomatoes in containers.
One plant per container with new potting soil every year and the
container cleaned very very well. (The old potting soil becomes fill for
parts of the lawn, dumped as soon as the season ends). I also grow
potatoes in containers quite successfully and leave my plots for the
veggies that thrive in almost anything like carrots, onions, garlic,
turnip and beets.

..

Zone 5 in Canada's Far East.