Soil borne diseases are controlled by increasing the biological activity in the soil. When microbes are plentiful, the beneficial organisms control the pathogens. Pathogens themselves are not pests when in their proper populations. The best products for stimulating life and the balancing of biological activity in the soil and thus controlling soil borne diseases include cornmeal, garlic, molasses, compost and mycorrhizal fungi products.
A broader scale soil borne diseases can be controlled by improving and maintaining drainage, keeping bare soil mulched, and planting native and adapted plants. Common sense is the basic answer.