Doesn't look like it to me. What sort of feed have you given it lately? Did you inherit the plant and just put it there or did you just buy the property plant and all? If you really want to know send some good and infected plant material to a lab and have it looked at. For both diseases and nutritional toxicities. It doesn't look like a deficiency. Most garden woes are self-inflicted.

Wow, I just came here to ask the same question! My clematis (also a Niobe) is having the same problem -- a purple spot forms, turns brown, and then the leaf goes yellow. The entire lower third of my plant is showing this. Any help?

COTW is trying to collect pics and has a link for diseases and pests...that looks like one of those NON-Serious leaf spots...is it getting enough water?..Jeanne

Here is a link that might be useful: COTW Disease and Pests

What I meant is that the plant was already there when we bought the house. Last year I hardly watered it much with my kids being around all the time and not in a condusive spot. This year tons of rain so I have only watered it a few times. I don't recall it looking like this last year but I can't be sure.

Tons of blooms today, what would you do?

It sounds as if it isn't a watering issue so I would assume that it is fungal in nature, especially if it develops as Valeree describes. The safest thing to do would be to get a general purpose fungicide and start using it on the plant. Just realize that fungal issues, including mildew, are not cured once established on the leaves. Fungicides typically only prevent the issue on newly formed leaves or noninfected leaves.

One other point to consider is that Niobe, if treated as a type II, can develop yellowing leaves on the lower stems as the plant ages and the stems become more woody in nature. That is why mine is treated as a type III.

Aha! So I should have cut it down to about 6 inches in March or so? What would you suggest doing now after it blooms?

Why not Redsox? If nothing else, it might get you another round of blooms later in the season and will rid you of the discolored leaves. If you don't get reblooms, then you will have the plant set up for next year!

Hard pruning will definetly take care of the problem right now. Not knowing the exact cause will just prolong it. Some Fungicides are broad spectrum and some are specific. The good stuff isn't cheap and a person(in general) that won't spend more than 6 bucks on a plant won't even consider buying the good stuff. And buy the way if you don't know what you're fighting then how do you know what to buy? Kitchen sink approach doesn't always work.