@breeze. My favourite patio clematis is showing signs of wilt though it is flowering. I sprayed it with Bordeaux mix last week. It is throwing up some new stems as well but these are not looking too healthy so is a light watering with the Bordeaux mix in order.
If it survives perhaps I should repot it into a plastic pot as it is in a clay pot and I have to water it a lot as it dries out
If it's got wilt on one stem they will all succumb, you can't stop the ones above ground from catching it, but you can save the plant. Spraying the stems & leaves doesn't work as the fungus will already be inside them. The best thing to do is cut the stems, all of them, right down. I know it's heartbreaking but it's the best way. Then you need to water the plant with the fungicide. Give it a good soaking.
As it's in a pot, you might be better to cut the stems down to about six inches above the compost surface, rather than to the ground like you would in ones planted out. Just incase there's not much stem under the soil, did you plant it deeply? At least five or six inches deeper than in it's original pot?
Put it in a bigger pot so you can bury it deeper. It will give the roots more room too, clematis are thirsty, greedy plants.
Plastic is better than clay as water can't evaporate as quickly. It's a good idea, once it's growing again, to put something on the surface of the pot to help stop surface evaporation & to shade the roots, they like a cool root run. Gravel or chippings, even a few stones will do.
To help prevent it happening again, water it next spring with your fungicide as it's beginning to put on growth. They usually grow out of it once they're well established, though you can still get the odd case of it, especially with ones grown in pots.