I'm assuming you're saying too much water and that as things start drying up, the problem will subside and not continue? Would it help if I removed the compost mulch which is at it's base?

Water stress means a shortage of water in the top of the plant. That can occur for various reasons.

Typically the roots can't take up adequate water to keep the top turgid and healthy. So that most often means that the soil (or potting mix) is dry. But other circumstances result in the same effect.

Among these are recent transplanting (roots missing), root damage from whatever reason (too wet; too dry; digging or construction which damaged part of the roots) and so on.

I would say that it looks a bit like a fungus to me. First, let's look at a biotic factor like a fungus versus an abiotic factor such as water stress (too much or too little water). I'm seeing leaves above and below the affected leaves (both older and younger) which are not being hit by the same problem. In addition, you can see leaves of the same age which are at different stages of damage. Those things say biotic to me. Also, dead tissue that results for lack of water tends to move from the margins inward much like salt burn (which are often related). I'm gonna go fungus because of the round-edged intervienal lesions as opposed to the angular lesions that you get from a bacteria. Also, you can see that the dead spots are surrounded by a purple ring which often (but not always) indicates fungal infection before it will point to a bacterial infection which more often than not turns watery yellow around the dead tissue.
You can't really "cure" sick leaves. I don't know what the particular pathogen is that's causing the spots, but if it were me I would just pluck the dead leaves, toss them in the trash, and give the rest of the plant a spray with a general purpose fungicide. I'd say an elemental sulfur spray but I don't know what your weather is like right now and and sulfur would be a bad idea if temperatures are exceeding 80 F or 26.7 C. Also, try to avoid overhead watering if you can. You're stems look healthy which suggests that this is a simple leaf spot. It most likely won't kill your plants and vigilance can keep the spot under control.

Twas said: "I'm seeing leaves above and below the affected leaves (both older and younger) which are not being hit by the same problem."

Yes, indeed. Stress is a temporary thing. newer leaves are fine, as can be older leaves.

Was also said: "dead tissue that results for lack of water tends to move from the margins inward much like salt burn"

Yes, indeed. Look closely on the large central leaves -- the edges are dry. And the dry zones between the veins are classic for acute stress. Whereas browning & drying moving gradually upward from the tip is chronic stress.

Again, I say abiotic problem -- that is, non-living, as in not fungal.

Yep, we're seeing the same things and interpreting them differently. That's what makes plant diseases so tough/interesting. Compared to things like people, plants only have a handful of responses to attack and stress to chose from and it can be the same or very similar responses to many different problems both biotic and abiotic. You make good points, jean001 and you could definatley be correct. But I'm still gonna go with fungus because tiffy seemed concerned about too much water (which would give a completely different set of symptoms). Also, she mentioned that the other plants around it are not having similar problems. Without knowing what those other plants are, I would generally assume that if one plant were water stressed that badly, surrounding plants would also be showing symptoms. Biotic factors can be very host specific. Abiotic factors less so.
I feel like we're Bugs and Daffy:
Biotic!
Abiotic!
Biotic!
Abiotic!
Wabbit season!

Also, upon closer inspection of the picture, I notice that the two most prominant leaves of the same age show the problem at very different stages. If this where an episode of water stress, leaves of the same age that went through the same problem at the same time should have a more similar appearence. Also, you can see that there are purple spots beginning to form on leaves above and below the two worst leaves. To me, that looks like the beginnings of new infections from the same pathogen.

On the subject of purple, water stress lesions usually have one of two things. Either no margin seperating brown from green, or a yellow margin which is called the plesionecrotic or "nearly dead" region. Purple is a production of phenolic compounds, more specifically in this case, anthocyanin. It is a pigment with antibiotic properties. It is produced as a reaction to attack from a biotic agent and is an attempt by the plant to kill whatever is attacking. That plant has all kinds of purple going on.

Correction: Anthocyanin is not the antibiotic but rather one of the phenols produced in a complex of phenolic compounds which together have antibiotic properties.

Purpling can be a sign of stress in and of itself. Indicates damage that wasn't sufficient to totally kill the leaf tissues.

Well.....kind of. Purpling isn't an "all purpose" response to stress in general. It only happens in response to certain types of stress. If you chill a plant, or deprive it of sunlight, or cause mechanical injury, and it survives, it's not going to react by turning purple like a bruise after the fact. Nor will water stress alone make a plant purple. An attack from a fungal pathogen in many cases will make it purple. (as well as certain nutrient difficies, nutrient excess toxicities, response to mis-application of chemicals, etc.) However, I will grant you this: You still may be correct. If it were lesions from an abiotic source, it is possible that saphrophytes have moved in to feed on the dead tissue and the plant is responding to those where they make contact with still-living leaf tissue. (although that would only address the purpling immediatley adjacent to the lesions) But, when you stack up purple splotches and rings surrounding dead spots along with all the other clues, they point to a fungal pathogen as the the most likely candidate for the primary source of stress for this plant.

Well, you've both provided great info and I appreciate it.

The vine was just planted last fall and showed what I thought were signs of stress from being at a box store garden center where sometimes plants aren't cared for properly. It may have had a fungus to start with. Can't quite remember.

I will also investigate the water stress issue. The only thing I can see which would be causing this at this time would be moles, but I've seen no signs of them since our cat ate quite a few this spring...

The vine is located in a raised bed so I don't think drainage is an issue.

So I'll check the soil/roots, and then do a treatment with the sulfur and see what happens.

Thanks again! I enjoyed the info!!

Aha! Planted just last fall!

So, I still say water stress, this due to an as yet inadequate root system.

Oops. I forgot to add that I still doubt any fungus is present, including a secondary saprophyte.

Nine or so months is a fair amount of time to establish.
As far as the iron-clad declaration that no fungus of any type is present, can you give a reason? I'm really pretty curious at this point.

Just a note. Some plants do purple up when chilled. It's a phenomenon I see a lot doing winter growing in greenhouses. Lantana is a prime example. I move them to a hotter house as soon as I fire another one up. It is a nutrient deficiency because of poor root uptake. I don't think that is what is going on with those, however.