Clematis wilt
Clematis wilt disease is caused by a fungus that enters the plant through a wound, made either by an insect or an abrasion, such as rubbing from a plant tie. The top of the clematis suddenly wilts, collapses and dies back, and the problem quickly spreads downwards through the plant.
When the problem spreads from a leaf, its stalk turns black. Cut back affected stems to healthy growth, even if this means to below ground level, and the clematis should send up new shoots. Dispose of infected foliage, as the fungus can survive on debris left on the ground.
If the problem recurs, replant in rich, fertile, well-drained soil, with the top of the rootball 8cm below ground. Avoid stressing the plant by keeping it well watered and shading the roots – try covering the root area with slates or stones to keep it cool.