Clematis Wilt Treatment – How To Prevent Wilt In Clematis Vines

Clematis wilt is a devastating condition that causes clematis vines to shrivel and die, usually in early summer just as the plants are beginning to show vigorous growth. There is no chemical clematis wilt treatment, but there are several things you can do to help the plant survive. Continue reading to learn more about what causes clematis wilt and how to prevent it.

What is Clematis Wilt?

The first step in treating or preventing clematis wilting is becoming familiar with the issue and its causes. So what is clematis wilt? Clematis wilt, also called clematis leaf and stem spot, is a fungal disease that progresses rapidly. A careful observer may see black spots on the leaves and stems as the disease begins, but the symptoms often go undetected until the entire stem wilts and dies.

What Causes Clematis Wilt?

Learning what causes clematis wilt is important in its treatment and prevention as well. Clematis wilt occurs when a fungus infects a clematis stem near the soil line. The fungus causes lesions, which cut off the vine’s flow of water through the stems, and all parts of the plant above the injury wilt and die. A variety of fungi can cause clematis wilt.

How to Prevent Wilt in Clematis

Keeping the plant healthy goes a long way toward preventing clematis wilt. Plant the vine in a neutral to slightly alkaline soil in a location protected from strong winds that might damage the vines. The roots should be shaded or under a layer of mulch, and the upper part of the vine needs full sun.

When you plant the vine, bury it so that at least two buds along the stem are underground. This helps the vine develop a strong root system to nourish the plant.

Keep the soil evenly moist to prevent stress. Water the soil rather than the vine, and water early in the day so that any moisture that splashes onto the plant will have plenty of time to dry before sunset.

In addition, there are some small-flowering clematis vines that are resistant to clematis wilt, including Clematis macropetala, Clematis montana, Clematis viticella and Clematis alpine.

Clematis Wilt Treatment

Damage is most often seen in early summer and during periods of damp weather. Prune out damaged parts of the vine to help prevent the spread of the fungus. Even when the vines are ravaged by the disease, the roots generally survive and the plant sends up new shoots the following season.

Good fall cleanup is an important part of treating and preventing clematis wilting. Trim affected vines as close to the ground as possible, and remove and destroy all fallen vines and leaves.

Clematis wiltPhona clematidina, Ascochyta clematidina

Look for

Shoots, buds and leaves that are wilting and quickly dying back towards the roots, turning black as the plant dies. In some cases discoloured lesions can appear on stems.

Plants affected

  • Clematis, especially varieties and cultivars that produce large blooms.


  • Clematis wilt is a very common although little understood problem.
  • The disease is caused by a fungus known as Phoma clematidina.
  • The fungus causes lesions on the plant’s stems which in contact with water, release their spores that spread the infection.
  • The disease is thought to also be affected by water-logging, wind and failed grafts.
  • Sometimes clematis wilt is caused or aggravated by root damage and damage caused by slugs and insects, possibly transporting the spores.
  • The disease is rarely fatal to the plant and new shoots normally reappear in the next season.
  • Clematis wilt is often misdiagnosed because damage to the stems and lack of moisture at the roots causes wilting anyway.
  • Critical points that define Clematis Wilt are: Leaves going black not brown; blackening from the top down; rapid onset.



Products containing the following chemical ingredients are all effective on Clematis wilt

  • Myclobutanil
  • Penconazole.

Note: It is important to read manufacturer’s instructions for use and the associated safety data information before applying chemical treatments.


  • Cut back affected stems to ground level
  • Avoid plant stress by keeping the soil well fed and mulched.
  • Plant more resistant varieties of clematis such as c. montana, C. viticella or C. tangutica.
  • Plant Clematis deeply, around 6 inches lower than other plants. This encourages more bud development, so the plant can recover more easily if all the stems above ground need to be cut back.
  • Put a shield around the base of the plants to stop infected water splashing up onto the base of the stems. The top of a fizzy drinks bottle is good for this.

Clematis Wilt

Posted June 26, 2009 09:04h in Pests & Diseases by Becky Robert

This month you may have noticed shriveling of some stems on your clematis, while others of us have been so unlucky as to experience a dramatic demise of the entire plant shriveling and turning black in a week. These symptoms are typical of a disease called clematis wilt.


These dramatic symptoms most often manifest just as the plant is about to flower, typically striking the flower buds and new growth first. In my research, I have found 2 fungi credited with causing this theatrical demise, Phoma clematidina and Ascochyta clematidina. These pathogens enter the vine’s vascular system and clog the fluid-carrying tubes causing all parts of the plant above the clog to wilt as if it needs water.

The new growth of Clematis ‘Piccadilly’ shriveled from clematis wilt. photo credit: R. Robert


Luckily, this disease does not attack the roots. Simply prune out the affected stems or trim the plant to the ground. New shoots will emerge and some cultivars will bloom again in the same season. Be sure to disinfect your tools after pruning the infected plants to avoid transmitting the disease to other plants.

Once the plant has established heavy, tough stems the problem appears to lessen. In other words, the plant can outgrow the disease. These symptoms have lead some gardeners to call the disease “juvenile wilt disease”.

Clematis addisonii, a small-flowered species. photo credit: R. Maurer

These fungi appear to primarily attack early-season, large-flowering hybrids. If you would like to avoid the trauma of seeing your entire clematis shrivel up and die, plant small-flowered species like Clematis montana, C. macropetala, C. alpine, and C. viticella.

How to Care for Evergreen Clematis Plant

Images of Clematis plant and pictures

Recently a new fashion trend as vertical gardening has emerged in landscape designing. It has shown to be a very practical and efficient mean of area decoration. Its use allows hiding the unsightly buildings and creating gorgeous green corners. However, not all of the plants are suitable for this purpose; they need to have special features. Clematis is perfect for creating fascinating green landscapes and can be grown outdoors or indoors.
Its maintenance in general includes watering, fertilizing, nothing special. Therefore, any florist can afford caring for clematis. Nevertheless, the process of planting is associated with some difficulties.

Clematis from the buttercup family includes up to 300 species of plants with different shapes, colors and sizes of flowers, which is why it is such an appeal to gardeners.

Today clematis is one of the most popular plants used for vertical landscaping and has many wonderful varieties and forms as a result of plant breeding.

Clematis is a herbaceous perennial vine that has flexible steams and shoots that rise to a height of 3 meters, large(flower diameter 5-15 cm) or small(2-5cm in diameter). It blooms profusely and for a long time(up to 3 months) and with good care up to 500 white, yellow, pink, strawberry, cherry-red, blue, violet flowers can simultaneously bloom on one bush. All this causes its widespread use in decorative planting. The most impressively look amazing compositions with all sorts of clematis flower color combinations.

Start Off by Planting Your Clematis. Care Instructions for Dummies

Clematis prefers fertile sandy loamy soil rich with humus, from alkaline to slightly acidic reaction. Since clematis grow in one place for more than 20 years, the soil must be arduously prepared in advance. Usually you need to dig holes not less than 60x60x60 cm, for a group planting the entire planting area must be prepared. The upper layer of the earth should be excavated from the pit and purified from the roots of perennial weeds.
Then the soil is mixed with 2-3 buckets of humus and compost, 1 bucket of peat and sand, 100-150 g of superphosphate, 200 g of mineral fertilizer, preferably 100g of lime or chalk, 200 g of ashes.

More peat, humus, clay is added into the light soils. If the area’s soil is moist, dense or loamy, a 10-15 cm layer of gravel, broken bricks or coarse sand is poured at the bottom of the pit. Thoroughly mixed soil is poured into the pit and then sealed.
This process is best to be carried out during autumn in southern areas and in spring or early autumn in areas that are situated further to the north.

You have to install a proper and rigid support in the center of the pit. A stretched rope will not do any

good, as it will not be able to protect the young vines from wind gusts. After having filled half of the pit with soil, you need to make a hill from which the roots of clematis will be straightening down to the sides and the bottom.
Hold the plant with one hand and the mixture close to the roots, making sure that your plant is deeply planted. New buds, shoots and roots will subsequently form after the development of the tillering center. These bushes better tolerate harsh winters and suffer less from the heat.

If you plant clematis at the same level with the surface they will be ephemeral, their root system consists out of 1-2 stems and suffers from waterlogging.

The bigger the seed is the deeper it should be planted: 8-12 cm deep for young biennial plants, 12-18 cm – for big adult or divided plants. If you are going to plant clematis in spring the planting hole should not be filled with soil to the brim, you must leave 5-8 cm unfilled. After having planted clematis, you need to abundantly water it, shade it from the sun and mulch the soil around the plant with peat.
When planting clematis in autumn the planting hole is filled to the brim and the aboveground part is cut to the ground level or slightly higher.

Requirements for the Planting Material

During the autumn planting clematis should have developed vegetative buds and at least one shoot in the spring. The seeds should have at least 3 roots (10 cm in length). It is important to use only healthy planting material: roots of the seeds should be elastic, without any visible damage, blisters or nodules.

Clematis Care and Growing Conditions

During spring clematis plants are fertilized a lime mixture (200 g of lime per 10 liter of water per square meter). When the weather is dry, plants should be watered abundantly but not often; make sure that the water jet does not reach the central part of the bush.

Clematis should be fertilized at least four times per season with mineral fertilizer with micronutrients (20-40 g per 10 liters or diluted with fermenter mullein), mineral and organic fertilization are alternated.

Since clematis can suffer from overheat and dryness, in the spring the soil must be loosened and then mulched with peat or humus (in northern regions) or sawdust(in southern regions). In spring the vines should be tied and directed in the right direction. Otherwise, the shoots are going to intertwine so much that you will not be able to unravel them.
Before sheltering the plants for the winter season in autumn, carefully prune the bushes and remove the old leaves. During the first two-three years in fall or early spring the bushes are fertilized with rotted manure mixed with any king of potash or phosphate fertilizer as well as wood ashes (a handful for each bucket of compost). Clematis should be fertilized with liquid fertilizer every 10-15 days in small doses.
Are you pondering on the question of when to transplant clematis? The best time to transplant an existing clematis is while the plant is dormant before the new season’s growth begins.

Pests and Diseases of Clematis

Clematis most often suffer from fungal diseases as wilting. Plant’s tissues lose elasticity, then wither and dry out. There are a couple of pathogens of such problems, they live in the soil and affect primarily the root system of the plant.
Therefore, it is very important to follow the agro-technical requirements, especially since the disease can manifest itself even in the early spring. In May you should remove the infected area and water the plant with a two percent solution of Bayleton. Severely affected plants need to be removed along with a lump of soil and the place where they were growing must be disinfected. Bayleton also fights against such diseases as gray mold and mildew.
Curling of the leaves might also turn out to be a virus. Clematis is also affected rust fungal disease which manifests itself as orange pads on the leaves and the shoots in spring.

Maintenance and Cutting of the Clematis Vines. How to Prune Clematis?

The beauty of clematis largely depends on how well the trimming was done. When planting you need to shorten the shoots, it is important for the formation of the aerial part of the plant and the root system’s development.
A regulating pruning is carried out during the summer. In order to prolong the blooming period, a part of the shoots is cut in spring. In early summer the vines can be shortened again to the first vegetative buds from which the new shoots and buds are going to grow.

Different Species of Evergreen Clematis

Blooming of different types of clematis occurs in different years, so it is important to know when to trim the vines.

Clematis Jackmanii

Rapid growth, long and abundant blooming, a variety of colors and large flower sizes make clematis jackmanii on of the most popular among the other clematis species. It is a woody vine that reaches 3-4 meters in height with imparipinnate leaves. Its flowers reach 10-14 cm in diameter and have four or sometimes six broad sepals.
The flower color is most likely to be violet-purple or pinkish. Blooming is usually very long, from June up to mid-September. The achenes that form the inflorescence have a whitish color, that is why their fruits in the sun acquire a beautiful silver color. Their maturation occurs at the end of September or at the beginning of October. Clematis jackmanii is winter-hardy but a preventive shelter is desirable.

Сlematis Armandii

Сlematis armandii is a shrubby vine up to 4-5 meters in height. The leaves are often simple with an oblong-ovate shape, large, leathery, glossy and have a dark green or green color. Сlematis armandii profusely blooms in the southern areas in April and May on the overwintered shoots. It can reproduce by seeds, green cuttings and grafting.
Heavily overgrown shoots should be shortened. It is better to plant it in a protected place. Сlematis armandii grows well on the coast of the Black Sea and Caucasus. It is recommended for vertical gardening in the subtropics, as well as for winter gardens and as a wildcard culture.

How to Propagate Sweet Autumn Clematis Vine

Clematis sweet autumn vine images appeal can lead even the most starveling gardener to attempt its cultivation. Who wouldn’t be seduced by the pictures of a climbing vine that gives off ineffable charm?

How to Grow Clematis from Seeds

Unfortunately clematis can be very expensive to purchase for many gardeners; in order to propagate clematis from a seed you need to learn as much as you can about the germination process

All publications about Clematis are below

Clematis wilt

Clematis wilt is caused by a fungus that enters the plant through a wound made by an insect or an abrasion, such as rubbing from a plant tie. It’s spread by water splash, and blocks the uptake of water in the stems, causing instant collapse. Infected foliage must be disposed of immediately, as the fungus can survive on the plant if left lying on the ground. The early, large-flowering varieties are most prone to attack, with smaller-flowering species (eg, C. montana) being the most resistant.



The top of a 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.

Find it on



Cut back affected stems to healthy growth, even if this means to below ground level, and the clematis should send up new shoots. Bin the infected material, don’t compost it. 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 over the root area with slates or stones to keep it cool.

Rhs level 2 certificate year 2 week 19 2019

Rhs level 2 certificate year 2 week 19 2019

  1. 1. RHS Level 2 Certificate Year 2 Week 19 – Introduction to plant diseases and disorders. Physiological disorders and fungal diseases.
  2. 2. Learning Objectives •Explain why plant diseases need to be controlled •State what is meant by the term ‘plant disease’. •Describe the damage caused by plant diseases to include: grey mould, strawberry powdery mildew, damping off, honey fungus, rose black spot, potato blight, club root, holly hock rust. •Describe in outline the life-cycles of: damping off, clubroot, potato blight, honey fungus •Describe methods of spread of EACH of the diseases named above •Describe TWO different methods of minimising the effects (including prevention) of EACH of the diseases stated above. Methods to be selected from more than one of the control options (physical, cultural, or chemical) available. •Explain how knowledge of the life-cycle and biology of diseases stated above contribute to the success of their
  3. 3. Physiological Disorders  Plant problems caused not by pests or disease but by some problem in the environment.  For example: Water availability: frost causes browning of foliage; strong winds, especially in winter when the ground is frozen, can cause die back in conifers.  Fasciation: distorted growth due to damage at the growing tips of stems, flowers and fruit.  Nutrient deficiencies – e.g. interveinal chlorosis in Rhododendron sp caused by iron deficiency in high pH soil.  Lack of light – etioleted or leaning growth caused by plants growing with insufficient light.  Damage to plant cells – fasication.
  4. 4. Fasciation of Syringia vulgaris (Lilac) shoot
  5. 5. Plant Disease  Damage caused to plants by some disease causing agent – bacteria, viruses or fungi. Collectively disease causing agents are known as pathogens.  Plants do not have an immune system, unlike animals. If an individual plant survives a disease it will not be more resistant to another attack in the future.  Some cultivars however are genetically resistant to disease – they are less likely to get it or less affected than others in the same species.
  6. 6. Fungal diseases  Plants under stress are most susceptible to fungal infection – so growing healthy plants in the right place is a good control.  Many problem fungi are normally resident in dead and decaying plant material – moving to living plant tissue through damage to stems (e.g. Clematis wilt) or via dying leaves or flower spikes.  Some garden fungi are beneficial – mycorrhizal fungi form beneficial symbiosis with many plant roots
  7. 7. Grey Mould Botrytis cinerea  Wind spread spores colonise plant tissues in humid conditions producing fluffy white growth  Black fruiting bodies form which will split to release spores  Controls: no chemical; control humidity; cultural hygiene
  8. 8. Powdery Mildew  White or grey dusty growth on leaves and shoots; weaken the plant  Controls: cultural hygiene to remove spores; avoid water stress; no chemical controls now available to amateurs after withdrawal of myclobutanil.
  9. 9. Damping Off disease. Pythium sp., Phytopthera sp and Rhizoctonia)  Fungal disease of seedlings; causes them to rot at the base and die.  Encouraged by thick planting and cold wet soil.  Controls: Control humidity by not overwatering and sow thinly; no chemical controls. Strict hygiene when sowing and watering.
  10. 10. Clubroot  Not strictly a fungus, infects the vascular system of roots, prevents absorption of water and nutrients, leading to poor growth or death of plants. Affects Brassicas mainly.  Resting spores may persist for up to 20 years in the soil. No chemical control available.  Controls: remove infected plants and burn, remove all weeds as these may be alternate hosts. Crop rotation, grow resistant cultivars. Slight soil alkalinity reduces the ability of resting spores to ‘germinate’ so pH 7.5 – 8.5. Spread in soil so do not buy in plants. By David B. Langston – USDA Forest Service, imgnum=5077024, CC BY 3.0,
  11. 11. Honey Fungus  Severe fungal infection that attacks both dead and living wood.  Spread by tough black ‘bootlaces’ through the soil and then penetrates roots and grows into the tree. White web of mycelium may be seen just beneath the bark  Visible signs are yellow or pale brown mushrooms and sudden wilting or death of plant  Controls – remove and burn all parts of the affected plant; use soil barriers to prevent spread. Do not grow susceptible species.
  12. 12. Rose Black Spot  Black spots on leaves, sometimes with yellow halo. Can cause cankers on stems. Badly affected plants may defoliate, cankered stems can die back.  Controls: remove and burn fallen leaves, prune out cankered stems and burn. Chemical controls: tebuconazole or triticonazole or plant and fish oil sprays. However fungus mutates rapidly so spray programme of varied controls needed.  Older roses and species roses less affected than cluster and large flowered hybrids.
  13. 13. Potato late blight  Fungal spores carried by the wind settle onto leaves of Solanaceae (potatoes and tomatoes). When the correct conditions prevail (Smith Period) they ‘germinate’, penetrating the leaves and stems and forming spore bearing bodies, taking nutrients from the plant.  Causes black patches on foliage that spread and cause the collapse of the top growth; may be very rapid indeed.  No chemical controls available; cultural controls – burn all crop residues (even if not obviously affected), remove all tubers at harvest, no cull heaps. Grow resistant varieties. Crop rotation. Early varieties less affected than main crop.
  14. 14. Potato Blight life cycle
  15. 15. Holly Hock Rust  Bright orange spots on leaves and stems; older leaves show problem first. May cause complete defoliation.  Controls – Chemical: tebuconazole or triticonazole or plant and fish oil sprays for organic gardeners. However, fast mutating and reproducing fungus so this may mean weekly spraying. Cultural – grow as a biennial and replace plants after second year. Otherwise remove all top growth and debris in autumn and burn.
  16. 16. Learning Outcomes •Explain why plant diseases need to be controlled •State what is meant by the term ‘plant disease’. •Describe the damage caused by plant diseases to include: grey mould, strawberry powdery mildew, damping off, honey fungus, rose black spot, potato blight, club root. •Describe in outline the life-cycles of: damping off, clubroot, potato blight, honey fungus •Describe methods of spread of EACH of the diseases named above •Describe TWO different methods of minimising the effects (including prevention) of EACH of the diseases stated above. Methods to be selected from more than one of the control options (physical, cultural, or chemical) available. •Explain how knowledge of the life-cycle and biology of diseases stated above contribute to the success of their control.

How to Treat Clematis Wilt

In the book Clematis as a Garden Flower by Thomas Moore and George Jackman, published in 1877, there is no mention of the word wilt! Was there no such thing as Clematis Wilt in those days? It seems that such was the case judging from their enormous popularity a hundred years ago. Since then, however, wilt is a word to strike terror into the hearts of all clematis devotees. Did Clematis Wilt exist one hundred years ago? or was it hushed up in the catalogues and in Jackman’s and Moore’s book? If not, when did it start? It was prevalent in the early 1900s as William Robinson wrote a slim volume on clematis which I once possessed but have now lost. In this, writing I think about the year 1914, he accuses Nurserymen of bringing wilt into clematis by the practice of grafting. This has since been proved to be quite wrong, as when clematis are grafted, the stock is only used as a nurse-stock; by the time clematis are planted out into the garden the scion has produced its own roots and the stock is discarded. The modern method of producing clematis in most Nurseries these days is by cuttings and these have wilted just as easily as grafted plants. A gleam of hope has emerged, however, with the introduction of Benlate, a new fungicide which seems to exercise a certain control over Clematis Wilt, as one of my customers remarked in his letter, ‘Benlate than never.’ Gardeners would be well advised to spray the base of their plants with Benlate in the autumn and again in the spring and once a month during the summer. It seems to be at the base of the plants where this attack takes place. When wilt occurs it is as though the plant has been cut through with a knife or hoe. Everything above this spot hangs limply and it is especially infuriating when the plant is in full bud or bloom and was an apparently healthy-looking plant. The only thing that can be done when this happens is to cut the plant right down to the ground, no good watering and spraying the plant, the damage has been done and all that remains to do is to remove all the wilted stems and foliage. Provided the clematis has been planted deeply, then there is every chance of shoots soon coming up from the buried first pair of nodes. Water and feed well to encourage these nodes to develop.

Many theories have been advanced as to the cause of Clematis Wilt. Ernest Markham in his book Clematis, published by Country Life Ltd., even has a name for the fungus that is supposed to be the cause of the disease. He says, ‘In 1915 a Bulletin was published which dealt with Ascochyta clematidina, as this fatal disease is named. This Bulletin was written by Mr. W. O. Glover and published by the New York Agricultural Experimental Station in Geneva, New York, U.S.A.’

The action of the fungus was described as follows: ‘The plants are killed by the growth of the fungus down the petiole into the stems, thus girdling the plant at the node. The stem may be girdled also by the lesions anywhere in the internodes. Dead stubs left on the vines are a means of holding the disease over a period of time. New shoots may be formed below the girdled region, but the downward progress of the fungus ultimately kills the plant if the diseased tissue is not removed.’

He goes on to say that various spraying experiments were carried out, such as dusting with sulphur, spraying with Bordeaux mixture and with a mixture of 1 lb. soap and 6 lb. sulphur. The last-named seemed to be the most effective, but that sulphur alone was quite useless. He also goes on to say that clematis may become damaged in gales with vines cracking and allowing fungus to enter into the broken tissues.

In the book Garden Clematis by Stanley Whitehead, published by John Gifford Ltd., the author says that the disease has been known for over fifty years (his book was published in 1959), which seems to support the idea that a hundred years ago it was unknown. He says that the fungus Ascochyta clematindina described by the New York Experimental Station is not the same as Clematis Wilt, but is a form of stem rot or leaf spot, which leaves Clematis Wilt unidentified with no clue as to the cause or cure.

Christopher Lloyd in his book, Clematis, published in 1965 by Country Life Ltd., says, ‘My own unsubstantiated suspicions fall on our old enemy the Grey Mould fungus Botrytis cinerea. It is so like it to enter living plant tissue by way of a damaged or dead leaf stalk, since the large-flowering types never shed their leaves cleanly. Against this is the evidence that the fungus sometimes does its damage not at the node, but in between nodes.’

My own personal pet theory, which may be quite wrong, is that it is not a disease at all but a failure of the very thin stem to cope with the sudden demand for moisture from the stem leaves and flowers which results in a breakdown of the tissues at a certain spot. These die, causing everything above to be suddenly cut off from its life-giving sap, and consequently everything collapses. These collapses usually occur at times of high humidity when the plant is growing rapidly and requires several pints of water a day. So my answer is to make sure they have a good supply of water at the base of the roots by giving them a good soaking two or three times a week. Then as water washes out the nutrients from the soil they must be replaced by a liberal application of a general liquid fertiliser once a week. One reason that leads me to support this theory is that clematis grown by rivers always seem to be beautiful plants, and several people who live in such spots have told me that their plants never suffer from Clematis Wilt. With their soil, one has only to dig down a foot or two to come on to water, which means that the plants have a constant supply of water. The stems of their plants are also much thicker than plants of those less fortunate people who have to contend with hot, dry, hungry soils, and so perhaps are more able to draw up the extra moisture demanded at peak periods, without causing damage to the tissues. One way to give the plant a constant source of water is to bury a container about 2 feet underneath the clematis before planting. Fill with stones, top up with water and cover with peat. Then plant in the normal way. A pipe driven down to the container will enable you to top up with water during drought periods and your clematis should have a constant supply of moisture. Even a pipe driven down to below the roots will enable one to get water down to what must be a very dry spot.

Another way to help to avoid Clematis Wilt is to layer two or three shoots around the plant, which provides the plant with extra roots. The only snag about this idea is that one has to grow the plant a suitable size before it can be layered, and then it takes a year for the layer to root, and it is usually during this period that wilt occurs! Once a plant has developed a good thick stem, or, as with a Jackmanii variety, has several stems coming out of the ground, then wilt seldom happens.

In 1965 experiments were tried out in Holland and the following report was given in the Boskoop Annual Report:

Small-scale trials were carried out at an Experiment station. Large-scale trials on commercial holdings.

Infection trials were with isolates from two fungi: Ascochyta clematidina and Coniothyrium clematis-rectae. The following treatments were given: 1.: Mixing diseased plants from the previous year with potting soil of this year. 2.: Shoot wounded and agar with fungus mycelium applied. 3.: Agar with mycelium applied to shoot without wounding. 4.: Spore suspension of fungus injected into shoot. 5.: Spore suspension of fungus rubbed into leaf. 6.: Culture filtrate injected into stem. (No fungus injected, filtrate only.) Results: Treatments 1 and 6 gave no wilting.

Field trials with fungicides have been inconclusive but it is suggested that control might be possible with 0.1 per cent Tuzet applied to the base of the plant.

We often get letters from customers on the subject of wilt, and Mr. Jim Hodgkinson of Frodsham near Warrington has two theories. His first suggestion is that it is caused by a symbiotic union getting out of hand but he writes: ‘I’ve been looking into the reason why I seem to be so lucky in not getting wilt on my clematis, whilst others seem to get ‘it’ so frequently, either I do something, or don’t do something, which others miss. One thing I have noticed is that, as you know, when the stem swelk in the autumn, the epidermis splits longitudinally to reveal the tender cortex and inner portions. At this time I always spray with a fungicide (Benlate of Karathene) as, until the tissue hardens, the stem is open to attack. It could just be possible that spores enter the plant at this time and only reproduce in the spring, so that by the spring and early summer we already have a fungi within the plant, which have entered, not at the height of the growing season, but in the autumn.’

Mr. Hodgkinson’s theory, then, is supported by the findings of the Dutch trials when they suggest that the base of the plant should be sprayed with a fungicide.

Mr. R. W. Sidwell of Ashton-under-Hill, near Evesham, writes: ‘Wilting of leaves is due to failure to replace transpirational water losses. This may be due to infection with plant pathogens and there seems no doubt that under some conditions this can be the cause with Clematis Wilt. Cases are, however, known where it seems improbable that infection is the primary cause. ‘Most plants are capable of developing a certain amount of root pressure which may be sufficient to force water to the tops of the shoots but under conditions of high transpiration this is usually insufficient to replace lost water and the water columns then become in a state of tension rather than compression. This is certainly the case with clematis when at maximum water demand. ‘Water travels up plant stems mainly through the wood vessels which are literally water pipes. In the case of clematis these wood vessels are few in number and very large in size. They remain functional for about one year only and are replaced annually by fresh cambium growth. This exceptionally large size of wood vessel makes the water transport system of clematis particularly vulnerable. Stems with large numbers of small vessels are much better able to cope with heavy stresses in water demand. ‘All the cases of wilting that I have observed on planted-out plants could be explained by water shortage in the root zone, either through competition from other plants or other reasons. Plants grown in deep rich moist soil free from immediate competition have never wilted in my experience. ‘Wilting that I have observed is often just at peak growth, reached in early summer. This might possibly be connected with the ageing of the wood vessels before the newly developing ones are able to take over. This is pure theory but is worth investigating.’

Mr. Sidwell seems to support my theory, then, especially when he notes that plants grown in moist soil have never wilted as I have noticed that plants grown near rivers never wilt. So the answer here is lashings of water if your soil is light and dry.

My answer to Clematis Wilt then is, plant deeply with 3 or 4 inches of the stem below the soil, spray the base of the plant with Benlate in the autumn, again in the spring and during the summer at regular intervals. Keep the plants well watered and fed, especially during humid and quick-growing spells, make sure the soil is moist below the roots, and with a bit of luck this should prevent any attack of so-called wilt.

The Garden of Eaden

How to treat for clematis wilt

Clematis wilt is a very common, fast acting and devastating fungal disease that can affect all species of clematis, although it is more associated with the large flowering hybrids. The fungus has been identified as Ascochyta clematidina but it is believed that other fungal species may also have a part to play. Unfortunately the causes behind clematis wilt are still poorly understood and may not be the same from one plant to another.

Clematis wilt

Typically the younger leaves will suddenly begin to droop as though they are suffering from drought and will not recover when watered. Then the upper parts of the leaf stalks will then blacken followed by the leaves themselves which wither and die. The infection takes hold so quickly that the entire plant can be destroyed within just a couple of days!
Discoloured lesions can occur on the stem at or near ground level and you may witness dark patches on older, otherwise healthy leaves.
How the fungus acts upon the plant is not really known although it is believed that clematis wilt could be a soil based fungi whose spores enters the plant through wounds or insect damage during times of high humidity. Be that as it may there is no evidence that the fungus then develops either mycelium inside the plant or any external fruiting bodies.

How to mitigate clematis wilt

Spraying your clematis with a general systemic fungicide may act as a preventative measure but once clematis wilt has taken hold all that can be done is to cut all the stems down to ground level as soon as the disease has been identified.
The infected stems should be immediately bagged up for burning to prevent the spread of infection. Usually you can expect to see new growth from the base that same season which will be unaffected by the disease.
This is the reason why when planting new clematis, the current practice is to sink the root-ball 6 inches or so below the existing soil level. This encourages the formation of roots from the submerged section of the stem and these appear to be less liable to infection.
However if symptoms do recur repeat the above process and then remove the soil surrounding the root-ball to a depth of 12 inches and replace with fresh sterilised soil.

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