Planting disease resistant varieties is just one of the measures needed to reduce tomato "blight." Go here to learn about those measures:
When purchasing seeds or transplants, look for VNFT or some combination of these and other letters on the packet or label that indicate resistance. Unfortunately, varieties listed as resistant are not immune to the listed diseases and almost all varieties have little or no resistance to one of the most common tomato diseases-- septoria.
The following information may be of interest: