Saturday 05 May 2007
Clematis Diseases and Pests
Hello Fellow Gardeners,
Here is a helpful guide to let you diagnose what disease your clematis has, therefore allowing you to cure it!
Clematis Wilt
Clematis wilt is the most common disease affecting young clematis!
It is caused by a bacteria called Ascochyta clematidina. It can happen at any time but usually strikes right before the flower bud begins to open. The bacteria enters the plant through a break in the vine, most often caused by a lack of proper support, winter damage, or slugs. Large flower clematis seems to be more vulnerable than the small flower variety!
The signs… 
If your plant starts to wilt or die from the top, hanging down and looking droopy or even appears dead for no apparent reason, clematis wilt is probably the cause!
In order to save your clematis you must cut back your vine to about one inch past the healthy green tissue. If it is a severe infection then it is recommended that you use a fungicide called Benomyl or a systemic fungicide. Make sure to follow the directions on the back of the container and wear appropriate clothing while using these herbicides!
Mildew
Mildew usually appears towards the end of the flowering season and is usually caused by poor air circulation, lack of sunlight, or an abnormally wet season. If infection is severe use Cleary’s 3336 herbicides, otherwise do not worry it will not kill your plant!
Other conditions affecting your clematis may be:
Yellow leaves
Yellow leaves are caused by a magnesium deficiency. A dose of Epsom salts is recommended for the cure. For a large, two year old plant, about a half a cup of Epsom salts should do, followed by lots of water!
Green Flowers
Green flowers usually happen on white clematis, and is caused by a mineral deficiency. Make sure to give your clematis direct sunlight and add a dose of Sulphate of Potash to your regular feedings and that should do the trick!
No Flowers
Pruning at the wrong time, either by you or Mother Nature (hard winter die back) or over feeding your plant is usually the cause of your clematis not flowering. You can’t control Mother Nature, but if the problem is you– put down those pruners and slow down on the feedings!
For more information about clematis and remedies please take a look at these websites. They are jammed full of information and it never hurts to know a little more!
University of Minnesota Extension
If you would like to try some small flower clematis which are less susceptible to disease, here are some nice choices for cold climates…
Happy gardening,
Marie Suzanne
Marie | flowers, northern gardening
3 Responses to “ Clematis Diseases and Pests ”
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I have spots on my clematis leaves, they then turn yellow to brown and die. The bloom does not seem to be effected. It is not powdery mildew. Help. This happens every year.
HRLP! This was to be my first year to have my two clematis reach the top of the arbor, which it nearly did. Sadly, just before the blooms opened, large sections of the plant truned brown and brittle. The green leaves that are not brown and brittle have black spots. Both large clematises have very few blooms. Several years ago, it was so huge and gorgeous that strangers stopped in to look at it. Now, even I can’t stand to look at it. I want to chop all of it down to the ground. I think it is clematis wilt, but I’m no expert to be sure.