Not present in United Kingdom
Notifiable – see ‘Report a sighting’ below
Scientific name of causal agent - Ceratocystis platani
Plane tree wilt, also known as canker stain of plane, is a disease which can affect several species of plane trees (trees in the Platanus genus). It is caused by the ascomycete fungus Ceratocystis platani, which was formerly known as Ceratocystis platani f. platani.
Plane tree wilt is present in the United States and several European countries, including Italy, France, Switzerland, Greece, Turkey and Armenia. There are unconfirmed reports from some other European countries.
It is not known to be present in the UK. Affected trees decline so markedly that it is unlikely that the disease could be overlooked, so it is unlikely that if it had reached here it would have remained undetected. See ‘Official action’ below for details of a survey conducted in 2014.
C. platani can infect most species of plane trees. Among them is London plane (Platanus x acerifolia), which is widely grown in British towns and cities .
London plane is a hybrid, and its parent species, P. orientalis and P. occidentalis, can also be infected.
This pathogen poses a significant risk to plane trees in the UK because plane is widely used as an urban amenity species in parks and public gardens, and alongside streets and roads. It is vbalued for its shade, amenity value and toleration of air pollution and water shortages. Their habit of shedding bark allows them to cast off particulate pollutants, while their large, stiff leaves make them excellent shade trees. Once infected, trees die within three to seven years.
It can be spread easily through the movement of infected cuttings. It produces resilient, long-lived spores which spread the disease, and these can persist in soil and on un-sterilised pruning and cutting tools.
The disease’s presence in our near neighbours and trading partners in continental Europe heightens the risk of its being accidentally introduced into the UK.
Identification and symptoms
C. platani is a wilt pathogen which causes pronounced staining of the xylem (the cells which transport fluid and nutrients up the tree from the roots), severe wilting and yellowing (chlorosis) of the leaves, and tree death.
Staining can extend longitudinally (above and below) in the sapwood at a rate of 50–100cm per year. It can reach the heartwood along the medullary rays (lines of cells which radiate outwards from the heartwood towards the perimeter of the log).
Infected trees exhibit sparse chlorotic (yellowing) foliage, and sometimes sunken, elongated or lens-shaped cankers (like oozing sores) in the bark (below). These can become roughened and black with age.
Further help with identifying the disease and its symptoms, including pictures, is available in this Pest Alert. (Please note: where contact details in the Pest Alert differ from those given on this page, please use those on this page.)
Some of the 'Additional resources' listed below also have illustrations.
Report a sighting
Although plane tree wilt is not thought to be present in the UK, there is a risk of its being accidentally introduced. We therefore encourage tree and ground-care professionals, plane tree owners and managers, and the public, to be vigilant for signs of it and to report suspected sightings immediately.
People receiving or handling imported plane material should be especially vigilant.
- Report suspected sightings in Great Britain to us using TreeAlert.
- Report suspected sightings in Northern Ireland to the Irish plant health authorities using TreeCheck, the all-Ireland tree disease reporting tool.
Please note that TreeAlert and TreeCheck both require photographs to be uploaded. These should be clear, well-lit, close-up pictures of symptoms.
Alternatively, suspected sightings can be made directly to the relevant plant health authority. This is the preferred route for suspected sightings made on trade premises, such as nurseries and garden centres.
- In England and Wales, contact the local office of the Plant Health & Seeds Inspectorate (PHSI) of the Animal & Plant Health Agency (APHA), or the PHSI headquarters in York: e-mail: firstname.lastname@example.org; tel: 01904 405138; web: www.gov.uk/plant-health-controls.
- In Scotland, contact the Scottish Government’s Horticulture & Marketing Unit: e-mail: email@example.com; tel: 0131 244 8923; web: www.gov.scot/PlantHealth/PlantDiseases.
- In Northern Ireland, contact the DAERA Plant Health Inspection Branch: e-mail: firstname.lastname@example.org; tel: 0300 200 7847; web: daera-ni.gov.uk/topics/plant-and-tree-health/about-plant-and-tree-health.
In all cases, provide precise details of the location and, if possible, clear, well lit, close-up photographs of the symptoms.
Infection commonly occurs through spores entering fresh wounds on healthy plane trees, such as those made by wind damage, birds, insects, and tree-care tools such as saws and knives. Contaminated tree surgeons' and forestry workers' gloves, ropes, clothes and boots might also spread the fungus.
The disease can also be transferred through root contacts between neighbouring trees, and by water. This latter pathway is thought to be the main means by which the famous avenue of plane trees bordering the Canal du Midi in France became infected. (See 'Origins and background' below
Management and control
The disease mostly proliferates through human activity. Its spread can therefore be limited by sourcing plant material from regions free of the disease, and by practising strict biosecurity (plant hygiene), such as disinfecting tools with alcohol before moving on to the next tree. Larger agricultural and landscaping equipment such as terracing machinery should be jet-washed with water to remove any contaminated soil before moving to new sites.
C. platani can persist for months or years in affected wood and roots, so removal and burning of all infected material is the safest form of control. No effective chemical treatment is currently available.
Tolerant hybrid plane trees are being developed and one variety has been released to the market in France.
Further guidance on biosecurity is available from the UK Government website.
On behalf of the Forestry Commission, the London Tree Officers' Association (LTOA) surveyed 2,979 London plane trees in 2014 for symptoms of C. platani infection.
Inspections were undertaken at 53 sites across 28 London boroughs. More than half of the sites surveyed included potential hosts planted during the previous 10 years, and the sites ranged in size from a minimum of 20 to, in some cases, more than 200 trees. No positive findings of C. platani were detected in any of the trees inspected.
The response to discovery of a case in the UK would be guided by the Forestry Commission’s Contingency Plan.
The UK has European Union Protected Zone status for plane material to provide extra safeguards against accidental introductions of this disease on imported plane plants or wood. In short, the legislation effectively bans the movement of plane plants into the UK unless they have been grown in an area free of plane tree wilt, and are accompanied by a plant passport certifying this.
Visit the UK Government website for an explanation of the regulations applying to the importation of:
- plants, seeds, cuttings or other planting material, or consult the Animal & Plant Health Agency; and
- wood, timber and materials made of wood, or consult the Forestry Commission’s Plant Health Service.
Origins and background
The C. platani fungus is thought to have originated in North America. The evidence suggests that it was accidentally introduced to southern Europe from the eastern United States during World War II on crates and boxes made of infected plane wood and carrying military supplies: the first plane trees to be affected were in and around major port towns.
It spread rapidly through Italy and into France and Switzerland. Although its progress through France was initially slower, the fungus has been spreading northwards at a much faster rate in recent years.
For unknown reasons the disease seems to have become less significant in the United States in recent years, but Greece and south-east France have experienced serious losses of shade trees. It is seriously affecting the famous avenue of thousands of plane trees lining the banks of France’s Canal Du Midi, and many have had to be felled.