I recently purchased a house that came with several clematis
vines. I am not positive which
cultivars they are. They came up beautifully this spring and have
bloomed heavily. But now, two of them have wilted and turned brown -
they appear to be dead. Can you tell me what it is, and what I can
do to prevent this from happening again? I would hate to lose all of
these clematis vines!
That sounds like the heartbreak of
This common fungal disease causes the symptoms you have described.
It occurs most frequently on the large-flowered hybrid clematis
varieties. Species clematis and their hybrids, and small flowered
hybrids tend to be more resistant.
Clematis wilt is caused by the fungus Phoma clematidina. It often
occurs when the vines are growing vigorously. Succulent, new growth
tends to be more susceptible to infection than mature growth that
has hardened off.
When to expect Clematis problems
To add to the heartbreak, clematis wilt often
strikes just as the flower buds are about to open. Instead, the
entire vine wilts, and then turns brown right down to the ground. It
is most common when we have a very wet summer, as we did several
years ago, but I have received a number of questions about it this
On small plants, the entire plant can wilt and die in a matter of a
couple days. New shoots can grow from the roots, and often go on to
grow and bloom normally, so do not be in a hurry to dig the affected
vines out. On large, more mature plants that have many stems, some
stems are affected while others are not. Clematis wilt does not
always kill the entire plant, especially well-established specimens
such as yours.
Clematis growing on a
split rail fence
The best course of treatment is to prune out wilting stems as soon
as you notice them, at or even below the soil line. New stems should
grow from the roots to replace them. Clean up dead leaves and stems
as thoroughly as possible. Dispose of infected stems in the trash or
by burning them, rather than throwing them on the compost pile. The
fungus can survive in the soil surrounding infected plants. It
usually enters healthy stems through a wound, so be very careful
when you work around your vines and avoid nicking the delicate
stems. When you prune them, be sure to make clean cuts that will
heal rapidly. Have a trellis in place for them when they come up in
the spring, rather than trying to tie up the tangle of stems that
seem to grow overnight when you do not have the trellis in place
soon enough. You are guaranteed to break some of the stems when you
are wrestling them into place after the fact.
Proper planting location
It is also important to provide the proper environment for clematis
to grow well. These vines prefer an evenly moist, yet well-drained
soil. Heavy clay soil that holds too much moisture around the roots
and stems makes them more susceptible to clematis wilt. Clematis
performs best when the soil pH (acidity or alkalinity) is near
neutral, or 7.0, and when it receives at least six hours of direct
sun daily. Although clematis grows and blooms best in full sun, it
is important to mulch the roots, or underplant clematis with
low-growing flowers or groundcovers to shade their roots. If you use mulch, do not bury the base of the vine with it. Two inches of mulch
is sufficient to control weeds and cool the soil. Try to avoid
having the mulch physically contact the stems.
If you lose the affected plants entirely, consider planting ones
that are more resistant, such as our native virgin's bower (Clematis virginiana), sweet autumn clematis (Clematis terniflora) or one of
the viticella types (Clematis viticella), such as 'Ernest Markham,'
'Lady Betty Balfour,' or Madame Julia Correvon. Please remember that
resistant does not mean immune. When disease pressure is high and
environmental conditions are favorable, so-called resistant plants
can become infected, too.
How to prune Clematis
Bees in the Garden