Ruth69, Mine did the same thing and the best I have been able to find out is that there is a "downy mildew" epidemic going on right now with impatiens.(It is a fungus) Several websites have said the only thing to do is pull them up and destroy them. One site said to burn them or bury them at least 20 inches. Pulled mine up yesterday and it was painful....don't know if I will replant with anything at this point. Hope this helps.

Here is a link that might be useful: Royal Horticulture Society

That is shocking information, oldstew. I was calling it powdery mildew, I didn't realise it was downy mildew. A gardener on Irish radio said milk and water helped, maybe he didn't know what he was talking about.

Thanks for your comments. I emailed Bonnie Plants for help and they didn't mention this at all. However, they are sending me a check to cover what I lost. I told them they had to have a disease or something. I'll let you know if it is what I told them how much it costs me. Asked for a site to send pictures and no response on that just will send me a certificate for my loss. I shall go directly out and pull the rest up and dispose of them in the garbage.

Thanks again! Ruth

Milk really will help with downy mildew. I don't know if it will work on impatiens, but it will on vegetables.

According to Steve Bender's blog post, downy mildew is a water mold not a fungus. Really a bummer any way you look at it.

Here is a link that might be useful: Downy mildew