Wally, could you post photos of them? Could you define "dwindle?"
If your impatiens are dying from excess sun, heat or lack of water they will not affect other plants. If they have a disease or fungus, yes possibly, depends on what disease, what the other plants are and how close they are. If it's insects, depends on what else they like to eat. With photos maybe we can figure it out.
Funny, this is the time of year when my
patience with the garden starts to dwindle
