To clematis wilt, a disease that just can't wait even one week so we can first enjoy the flowers!
A fungus (Ascochyta clematidina) infects clematis stems, presumably through weak points such as cracks. The disease proliferates, kills that section of stem and everything above that point wilts and quickly dies.
Our biggest complaint is that Clematis wilt usually begins killing for the season at just about the time the large flowered hybrids are budding up to bloom (late May, for us). We watch the vine load itself with buds, happily anticipating a great show, then see sudden wilt in some or all of the tip growth and buds.
There is no cure for an infection already begun. The tips die first but the stem below will die, too, and with it all of its leaves and side shoots.
All of the large-flowered hybrids are prone to this disease and many other clematis species can be infected. If you love clematis and grow a number of them, it's not a question whether you will see wilt but when.
Clematis do have other troubles... but wilt disease is the most serious by so far and away as to eclipse the rest.
- Christopher Lloyd, in his book Clematis -
Good hygiene and prevention are the only known controls.
If a clematis wilts, cut out the affected stem below the dead/discolored section, which may mean cutting below the soil surface.
Remove all dead and discolored leaves, even from otherwise lively stems. The fungus can cause a leaf spot and although the pathogen can't move directly from leaf into stem its spores in the spot may become a source of infection to the stem. Burn suspect stems and leaves or dispose of them securely and at a distance from your garden.
If a clematis has not wilted and shows no other symptoms, it gains some protection from infection if regularly coated with a copper-based fungicide.
Don't plant new clematis into the same spot where wilt claimed a clematis.
Choose small flowered late blooming varieties rather than the wilt-susceptible large-flowered hybrids. There seems to be resistance and perhaps immunity in the small flowered, late blooming species C. alpina, C. macropetala and C. viticella, the glorious big spring bloomer C. montana and various shrubby- and groundcover types. (More about many other Clematis species in Clematis Types.
Always plant clematis at least an inch deep so that buried nodes will sucker, quickly creating a multi-stem vine. Then, if one stem of that plant is infected at the soil level and must be cut below the surface there may be unaffected stems to carry on.