Why are my impatients dying, again?

Once again, my impatients are dying off for no obvious reason. Not long ago, my beds looked like the bed in the pictures with the rosebush. Now they are looking like the other one with almost have of the impatients dying off. I have included a closeup as well.

This has happened to some degree or other for the last few years. I cannot find anything on the plants or roots that looks out of the ordinary. All of the inpatients get the same amount of water and fertilizer and all the beds are prepared the same way, so I have no explanation for why some of these suddenly die off and others look just fine. This doesn't seem to happen with any other plants in the yard.

The only different between these beds is that the one that is dying off has been edged and mulched with brown earthgrow mulch. I just didn't get to it with the other one yet. I can replant some here, but I am reluctant to do that without knowing what is causing the problem.

Advice would be appreciated.

LMHmedchem

You probably have the Impatiens downy mildew which once you have it, you probably won't be able to get rid of it. Allegedly a lot of garden centers, nurseries are going to stop carrying bedding impatiens due to this fungus.

http://msue.anr.msu.edu/news/impatiens_downy_mildew_a_curse_and_opportunity_for_your_garden

I am having a little bit of that,but the plants I bought early in Spring are doing better than the ones I bought in early June.I made this hanging basket later and it is still doing well except I am picking of a few yellow leaves here and there.

I have very carefully examined the leaves of all of the dying plants and I don't find any white material on the underside as the link suggests. The leaves seem to curl up as they are dying, but I don't know if that means anything. Impatients are pretty cheep this time of year, so I will replant and see if the next crop does any better.

All of my plants were planted at the same time in June. Some of them are doing very well, but this one bed is on the way out. This has happened to the occasional plant almost every year for a while now but I have never lost more than 5 plants or so.

LMHmedchem

That you are losing the same species in increasing numbers does hint that there is something in the soil, or else some nearby plant is interfering, and getting larger each year, causing more problems. Could be allelopathy, could be that the other plant hosts some disease or parasite.

Try this: Dig out a hole large enough to plant a large pot in there, pot and all.
Plant at least one Impatiens in the pot, not in contact with the soil.
Same location, but isolated from the soil.

If you continue to lose impatiens then it is time to switch to something else. Why fight a losing battle? New Guinea Impatiens are not affected like the Impatiens walleriana (bedding impatiens) to Impatiens Downy Mildew

Doing a Google search for dying impatiens shows many factors (downy mildew is one I mentioned due to a commercial grower stating the fact that once you get that mildew, then all hope is gone and that garden centers are dropping impatiens like hot cakes). Here are the top 5 hits that came up and most mention Impatiens Downy Mildew.

http://www.gardeningknowhow.com/ornamental/flowers/impatiens/impatiens-problems.htm

http://homeguides.sfgate.com/impatiens-flowers-dying-60209.html

http://www.almanac.com/blog/gardening-blog/impatient-impatiens

http://www.bettyongardening.com/gardening-articles/what-you-need-to-know-about-impatiens-blight-idm/

https://www.youtube.com/watch?v=Q-H3EIXRzhE

When I Google "disease on impatiens" I get this:

Well that image didn't come out very well. Here it is again after I crop into it. I hope it shows better on DG than the original.

http://davesgarden.com/guides/articles/view/4156