My guess is that the soil may have been to fertile. Once they deplete the soil they will probably flower more. It could also be from the heat many of my Impatiens species have stopped flowering and are just sitting there. They will start again once the weather cools. The white spots dont look dangerous to me and is more then likely environmental.

You're impatiens have a virus called--

tomato spotted wilt tospovirus

It is spread by thrips. It started in tomatoes at one time years ago but now it has spread to many different plants including Impatiens. Spray the plants with a fungicide--I'm sorry I can't tell you which one but your garden center should know.

You will probably have to do something about the thrips too if you see them

It not virus. If it were virus it would have spread through the whole plant not just a leaf or two. If it were wilt virus the plants would be wilting as if they had a lack of water. Mosaic virus the plants would have a mottled look to all the leaves. There is no cure for any virus the only course of action is to throw the plants away or burn them.

When a virus first starts and only 1 or 2 leaves are infected the plants do not wilt. It is only after it is all over the plant that they wilt.

You can indeed treat some viruses sucessfully if you get it early enough. The more it spreads the harder it will be to treat. I just had leaf spot on my impatiens and the plants infected are coming back.

The thing with viruses is to get it early. Pick off infected leaves so the spores can't spread to other leaves and spray with a fungicide for that disease and you have to spray often and treat the soil too because the virus may be there too

I've never heard of miracle grow being too fertile either. It's always been on the lower side as far as nutrients go and it has already been long enough for the nutrients to be depleted. I've always added more fertilizer to miracle grow potting and garden soils.