Is it true that impatiens have a disease this year that will contaminate the soil?
Yes, you are right there is a disease--a fungus--that infects only Impatiens walleriana. It looks a little like powdery mildew in the beginning and eventually ends up with the stems of the plants collapsing. If you suspect you have diseased Impatiens, dispose of them in a bag in the trash. Do not compost them. If you think you had the disease last year, use Begonias or New Guinea Impatiens or another annual as the spores for the disease may be in your soil. The suggested plants are immune, The disease only affects Impatiens walleriana.