Why clematis wilt

Common name Clematis wilt Scientific name Calophoma clematidina syn. Phoma clematidina, Ascochyta clematidina Plants affected Clematis spp. Main symptoms Rapid wilting and death Caused by Fungus. Jump to What is clematis wilt? Symptoms Control Biology. What is clematis wilt? Research has clarified two important points: Wilting in large-flowered hybrid cultivars may be caused by Calophoma clematidina , in which case it should be possible to find some of the symptoms described below Wilting in resistant hybrids and species clematis is very unlikely to be C.

These other problems are equally common on the large-flowered hybrids So, although wilting in clematis plants is often blamed on C. Symptoms The symptoms of fungal infection and environmental stress can be similar. Affected leaves may then shrivel and the leaf stalks turn black. Leaf infection is followed by wilting of the stems Infection can also occur directly through stems.

Freshly affected stems show black discolouration of tissue when split open Young healthy shoots may be produced from the base of affected stems, sometimes from below ground. Control Non-chemical control Try to create a suitable root environment by deep cultivation and mulching, to minimise root stress If clematis wilt infection is suspected, cut out all wilted stems back to healthy non-stained tissue and promptly destroy the affected material to prevent it contaminating the soil.

Clematis 'Comtesse de Bouchaud' ; C. Biology Calophoma clematidina can survive in the soil on dead plant material and organic matter. You may also like. Clematis slime flux. Clematis: green petal.

They are easily damaged while you tie them to a trellis, or by a strong wind. Slugs, snails and small rodents can also damage these fragile stems, usually close to the ground.

If the damage is extensive enough the plant will wilt. All of these abiotic problems cause wilt which leads gardeners to conclude that they have the disease; clematis wilt.

Jim Fisk, a clematis expert who was instrumental in making them popular in gardens and who has written several books on clematis, is of the opinion that clematis wilt is not a disease, and he is not alone.

This explanation is supported by gardeners who report that plants grown in soil where there is a good subsoil water source, never get clematis wilt. The problem usually happens just as the plant is ready to open a lot of flowers and all those expanding flowers put a big drain on water resources.

This fact, coupled with a very thin stem, seems to support the idea that clematis wilt is a watering issue. The disease angle has also been examined and there is now clear evidence that a known fungi can infect clematis and cause the observed symptoms. That fungi can be extracted from wilted plants and used to infect other plants.

Most authorities no longer believe it is just a watering issue, although a lack of water might explain some instances in gardens. I think it is best to consider watering issues along with slugs and wind as a possible explanation of the symptoms but not the true cause of the disease, clematis wilt.

Clematis showing a clear leaf spot infection, photo by Grant Smith. Several fungi have been found on clematis showing the disease symptoms but the most likely candidate is Phoma clematidina syn Ascochyta clematidina. The RHS calls it Calophoma clematidina. This is considered to be a wound pathogen that gains entry in plants when the tissue is damaged.

For example, a partial break in a stem allows the fungus to infect the plant. This is common near the soil where moisture levels are higher. Infection can also occur on leaves and on leaf petioles even without a wound. When the pathogen lands on a leaf its hyphae enters the leaf, causing a visible leaf spot. This leaf spot has a characteristic ring formation as shown in the above picture. Clematis leaf petiole is infected and half black as the hyphae move towards the main stem, photo by Grant Smith.

Once the leaf is infected, the fungal hyphae grow inside the leaf and work their way down the leaf petiole, causing the petiole to turn black. When this happens the stem above the infection starts turning black, but the stem below the infection stays green. The pathogen has essentially turned off the water that is normally moving up the stem and everything above the infected node, wilts. The time between infection and wilting is in the order 10 to 40 days.

Infection occurs more often on leaves that are wounded. Some clematis seem to be resistant to the disease and initially it was thought that the fungus could not penetrate resistant varieties, but does not seem to be the case. This process is not nearly as fast as gardeners think, because they normally only see the final wilting stage, which happens quickly.

Fungal infection has now entered the leaf node. Notice the petiole on the right, the source of infection, is now dead and the left one is still green, photo by Grant Smith. Phoma clematidina can survive on dead plant tissue and it can survive in soil. Water splashing on these materials will move the spores onto plants.

Garden tools can also move spores between plants. It is also suspected that some insects might move them and this could explain how the disease moves from garden to garden. Plant roots are not normally infected when planted in the ground, however, they can be severely damaged when the pathogen infects roots of containerized plants. The reason why roots in the ground are not affected is that this pathogen is not systemic; it does not travel throughout the plant.

Develop and improve products. List of Partners vendors. Warning To reduce the chance of clematis wilt re-infesting next year, remove all remaining vine and leaf growth in the fall and dispose of it outside of the garden—somewhere other than your compost bin. Featured Video. Related Topics. Plant Problems. Article Sources. The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles.

Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. University of Illinois Extension Clematis Wilt. Read More. Your Privacy Rights. To change or withdraw your consent choices for TheSpruce.

At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. These choices will be signaled globally to our partners and will not affect browsing data. It is curious, though, that wilt most often hits the plant at the most critical pre-blooming stage. Others have observed that clematis, even large flowered hybrids, that are planted in a spot where there is a subsoil water source such a spring, a stream or at a river bank, wilt is almost non-existent.

The wilt is truly a mystery. University studies, supported by the British Clematis Society and others, into the exact cause s of clematis wilt are presently under way in England.

The good news is that wilt is rarely fatal to the plant. It might take up to a year, but the plant will usually sprout a vigorous shoot from under the ground to live another day.

This is why it is important to place the transplant deeply, at least two to four inches deeper than the level in the starter pot. One wants to bury some latent buds so that the plant has a bud to sprout from if it is hit by the wilt or chewed off to the ground by one of natures many four legged animals.

Also make sure that the plant is well marked so you know that the new shoot that emerges next spring is not a weed. Until the real cause of clematis wilt is known, most growers use a systemic fungicide called Benomyl Benlate see Editors note below both as a prophylactic and as a cure for the problem.