My 3 year old clematis has suddenly developed yellowing leaves with brown spots. It was not cut down at all last fall and is already blooming and spreading. It is shaded by 3 foot high knockout roses. After some research I realize it needs better air circulation and possibly some copper fingicide? Should I cut the whole vine down to about a foot from the ground? The infected leaves are in the center of the vine, starting from the stem, possibly. I think it is a Jackmanii but am not 100% sure. Also, how do I prevent it from spreading to my roses?
I've had a lot of trouble with clematis getting clematis wilt. But if it is that, you will know it. All the leaves rapidly wilt like this, going from healthy to dead in a few days:
If you have that, best thing to do is cut any affected stems off at ground level and dispose of them (NOT in compost pile).
If your leaves are just yellowing/ spotted, but not wilting, it is something else, maybe some other kind of fungus.
Cut off all the affected leaves and then spray everything, including the roses with a baking soda solution, tablespoon of baking soda to a gallon of water.