To reduce chances of damping-off, root rot, and other problems associated with wet soils, choose a well drained garden site. If such a site is not available, plant on raised beds to promote drainage and faster warming of soil. Divert surface water from flowing across the garden. This will help prevent disease-causing organisms from coming into the garden from outside areas. Since many disease organisms live through the winter in old plants, plow under debris at least six inches deep before planting in such areas.
Sanitation is also effective for tobacco mosaic virus of tomato.
This virus, a common problem each season, can be transmitted through tobacco products. Wash your hands with soap and water before working in the garden if you use tobacco. Or, better still, if you can find varieties which are resistant to this virus pest, give them a try. Most seeds are treated with a fungicide, as indicated by their red, blue, or purple color. If they have not been treated with a fungicide, treat them yourself.