Just rotate your tomatoes into different spots each year. I've never had any diseases here, and have never sprayed either.
I think a mulch is beneficial here as well. Dirt/diseases are prevented from splashing up onto the fruit and foliage, eliminating many problems.

There are gardeners with disease and pest problems constantly and then there are gardeners with good, healthy soil that do not have these problems. If you build up your soil and make it good and healthy it will grow strong and healthy plants that are bothered much less by pests and diseases.
Since very few people rotate their perennials from bed to bed annually simple logic should tell you that it is not necessary to do that with annuals, and I know people that will dilegently plan and rotate their vegetables but will plant annual flowers in the same place every year. Does that make sense? As long as you replenish the nutrients lost each year and maintain a soil with a balanced nutrient load rotation is an unnecessary burden on a gardener with a small (less that 1/4 acre) garden.

Thank you, dirtslinger and kimmsr. I use the no till method, putting down compost, planting the tomatoes, then putting down a layer of newspaper and mulch on top of that. I really don't have the room to rotate. So far, the only problems I've had are poor soil and tomato worms. I'm dealing w/ the first w/ compost and manure, and the second by picking them off- easy enough. I love being able to pick fresh tomatoes! Brandy

Also, don't crowd your plants it you have experienced fungus problems. Allow the air to circulate.

Wayne

I have been on an organic program for 7 years and have recurring fungus problems. I scatter ordinary corn meal under the plants on a monthly basis. If I really get crazy, I will spray diluted milk on the leaves and stems. Dilution is 3 ounces of milk per gallon of water. You can use any kind of milk as long as it came from a mammal, heh, heh.