Not likely--by this time the hot weather has killed any active spores.

It likes stable temperatures around 66 degrees with a humidity above 85%. But, if the weather has been like that, it usually starts at the top of the plant and works its way down, unlike BS, which normally infects the bottom of the plant first.

Here is a link that might be useful: ARS Article on Downy Mildew

This post was edited by zack_lau on Fri, Jul 11, 14 at 14:29

Thank you Zack, I did read every thing I could on DM and it does not sound as if it's that. Disease is starting at the bottom going up. It's not black spot. As it progresses up the cane, it turns lime green with spots on cane and leaves and the thorns turn black. Spots on leaves are segregated and don't cross the veins. The bush is Pomponella an extremely healthy bush. I've already cut back to the crown bush appeared to sick to wait.There are two more Pomponellas in area. Hope someone knows what it is.

Patty I am sorry but I don't know what it is, never seen it before. Will you please provide a little more info.
Have you used fertilizer? What kind? How much. Sprayed? With what, how much. Weather? Watering? ETC
Maybe some kind of Root fungus?
Add anything else that may help.

I fertilized in spring with milorganite, alfalfa meal, cotton seed meal and a little epsom salt. Other than that they get leaves and straw pulled back from crown. They have always been happy blooming fools with just leaves and straw. I don't spray my roses with anything they are disease free roses especially the ADR roses. Had several rains followed by nights in the fifties but the days are warm. We are having the same weather pattern we had for winter. The weather men are calling it the summer polar vortex. Hot for a few days, then rain followed by cooler than normal for a few days. Haven't had to water yet. The snow melt is still in the ground. Been growing roses for 20 years and I've never seen this before. For what it's worth it looks bacterial. But I was by it two days ago and saw nothing. Saw it today and it was an oh,oh moment. Like seeing rrd in your roses. Perhaps not as deadly but she looked to be on deaths doorstep. Any thing else I can tell you about the rose? She in pretty good soil holds moisture but not flooded or muddy. Has been growing there for a good ten years.

Take a sample to your local county extention office. Keep us informed and good luck!

The leaves look sunburned or spray-burned, but that seems unlikely unless it's near a lot-line and your neighbor hit it with oil or something. The canes, I don't know, and the only way too find out is to do what kentucky_rose suggests.

That reminds me of the crud that Compte de Chambord used to get. I don't spray so he no longer lives with me.

You could try painting the infected areas with 3 % drugstore hydrogen peroxide. In addition to possibly actually killing whatever it is, it should help booster the plant's immune system.

Aspirin tablets placed in the ground may also help with the immune system.

http://forums2.gardenweb.com/forums/load/roses/msg0610421011109.html

Here is a link that might be useful: aspirin thread

Thank you everyone. Since I've already cut it down to the crown I'll be waiting to see what grows back. Will call extension Monday. My guess is that a sample of a rose bush would need to be sent to the University of Illinois.