Tree Health and Tree Surgery

Pruning trees often causes more harm than good. Good advice is the best start to care for your trees. The Council provides a |list of tree contractors and a |list of arboricultural consultants who work in the Elmbridge area and a |checklist to help you select a tree contractor.

Links to Sections on This Page
|Tree work operations
|Protected trees
|Current tree diseases prevalent in the borough
|Tree health links

|Tree Work Operations

Tree works generally fall into the following categories. Here is a guide to the terminology you are required to use when applying to the Council:

Crown Cleaning:
Crown cleaning removes the weak, diseased, and dead branches or limbs throughout the crown of the tree to prevent them being a nuisance or causing damage if they were to shed. This is normally the ONLY operation that is recommended to be carried out to a healthy tree.

Crown Reduction:
Crown reduction is the reduction of the complete outline dimension of the canopy, from the tips of the branches to suitable internal branches. Crown reduction is harmful to the tree as it removes the tree's leaf area and buds, important carbohydrate stores, and exposes cut branches to infection from disease. It also promotes vigorous regrowth at cut branches ends which will need regular future pruning to ensure it is safe. Crown reduction should be carried out only where there is a danger of damage or injury and no other solution is available. Crown reduction should be specified as a final height and spread rather than a percentage.

Crown Thinning:
Crown thinning removes a proportion of small live woody growth to reduce the density of the foliage throughout the canopy. It can help temporarily with light issues however most trees will grow back to their original or greater density within 2-3 years. It is important to avoid removing larger limbs from the central structure of the trees when thinning. This leads to 'lion-tailing' which causes limb failure. Crown thinning should be specified as a percentage.

Crown Raising/Lifting:
Crown raising or lifting increases the distance between the ground and the lower branches of the canopy by removing parts of branches or whole branches. Excessive harm to the tree should be prevented by ensuring the pruning wounds left do not exceed 50mm diameter. This is common practise where trees overhang roads or footpaths and should be specified as a final clearance height above the ground. This operation can also increase the amount of light in a garden.

Pollarding/Re-pollarding:
Young trees are sometimes pollarded to maintain them to a particular size or shape. This enables a large species to be grown in a confined environment. Cyclically the new growth is cut back to just above the previous pollard points. Historically pollarding was a way of growing trees for coppicing (wood production) in livestock fields. The trees were cut at a point above which the livestock could browse young shoots. Mature trees which have not be grown as pollards cannot be pollarded.

|Protected Trees

There are three ways to check if a tree is protected by TPO, Conservation Area, or Planning Condition. Either |use this form or |email Planning Services stating the address, location, and type of the tree, or call 01372 474792. You can also purchase a copy of a TPO from the Council for £16 inc. VAT.

If your tree is protected and you are considering works, the Council usually offers free pre-application advice to householders to discuss the best management of protected trees. Please |email Planning Services stating the location and type of the tree, or call 01372 474792.

Please note: From October 1st 2008 the government has introduced a mandatory application form for works to TPO'd trees. You can download the |tree works application form and |guidance notes for completing the application form or call 01372 474792.

|Current Tree Diseases Prevalent in the Borough

Horse Chestnut Leaf Miner

The horse chestnut leaf miner (Cameraria ohridella) is a moth of the lepidopteran family Gracillariidae. It probably originated in Asia, and first appeared in Europe in 1985. Its larvae are leaf miners on the Common Horse-chestnut (Aesculus hippocastanum), causing significant aesthetic damage to the trees.

The larva digs its way into the leaves of the tree, damaging the leaves and stunting growth. Infected leaves are covered in small brown patches, which spread rapidly across the entire tree, giving an autumnal appearance. Eventually the leaves die and drop off; when new ones grow they are again infected. This cycle can repeat itself several times in one season.

Damage by C. ohridella is primarily an aesthetic problem, and there is no evidence that infestation, on its own, causes dieback or a decline in tree health, or tree death. Consequently, there is no reason to fell and remove trees just because they are attacked by C. ohridella. Even severely infested trees will re-flush as normal in the following spring.

Further info can be found on the Forest Research website - |Horse chestnut leaf miner - Cameraria ohridella

Bleeding Canker of Horse Chestnut

Trees of all ages have been affected by the recent upsurge of Bleeding Canker (Pseudomonas syringae pv aesculi). Young trees with a stem diameter of only 10cm (4 inches) have been found with advanced symptoms. However, the impact on the environment can be particularly profound when large, mature trees are infected and disfigured by the disease. If the disease is severe and the areas of bark which are killed are extensive, large trees can undoubtedly be killed. However, younger trees (10-30 years old) are at greater risk and can succumb to the disease in just a few years (3-5) as the smaller diameter of their trunks means that they can be girdled more quickly.
No treatments are available.

Further info can be found on the Forest Research website - |Bleeding Canker of Horse Chestnut

Cypress Aphid

Aphids (Cinara cupressi or Cinara cupressivora) cause damage by sucking cell sap from within plant tissues. The Cypress Aphid causes patches of yellow foliage from the base of the tree in late spring and summer, which later turns brown and dies. Further branch die-back spreads upwards and to adjacent plants. The aphids are active from May to November, with numbers peaking in early to mid-summer. Although they are comparatively large aphids (2-4mm long) with pear-shaped grey to yellow-brown bodies, they can be difficult to see.

Treatments are not usually economically viable on large hedges but Smaller plants can be treated with an approved aphid control insecticide as soon as symptoms are seen (usually early summer). Domestic products now available contain either imidacloprid (Bayer Provado Ultimate Bug Killer Concentrate) or bifenthrin (Scotts Bug Clear, Doff All-In-One Garden Pest Killer or Bayer Sprayday Greenfly Killer Plus).

Further information is available from the Arboricultural Information Exchange - |Cypress aphid

Acute Oak Decline

Over the past three to four years there have been a growing number of reports across the country of oak trees with symptoms of severe and extensive stem bleeding. These symptoms have been linked to a new disease, Acute Oak Decline. Trees affected so far have been at least 50 years old and both of Britain's native oak species, pedunculate oak (Quercus robur) and sessile oak (Q. petraea), are affected.

Some trees die within 4 to 5 years of the onset of symptoms. In the early stages of the disease no changes in the condition of the health of the tree canopy are noticed but as trees approach death canopies may be visibly thinner. It is thought that bacteria cause AOD and tests are currently underway by Forest Research to identify these bacteria and confirm their role, they have also produced guidelines for monitoring potential symptoms. Council Tree Officers are liaising with Forest Research and are currently monitoring a number of protected trees, in connection with AOD.

Further info and contact details for reporting a tree with symptoms can be found on the Forest Research website - |Acute Oak Decline

It would also be very useful for Council Tree Officers to be informed of trees displaying symptoms of AOD as neighbouring trees may subsequently be infected. Please call 01372 474792.

Oak Processionary Moth

In 2006, larvae of the oak processionary moth, Thaumetopoea processionea (Notodontoidea: Thaumetopoeidae) were found at several locations in London. This species is a major defoliator of oak in Europe. The larvae (caterpillars) feed on the foliage of many species of oaks, including English, Sessile and Turkey oaks (Quercus robur, Q.petraea and Q.cerris). Hornbeam, hazel, beech, sweet chestnut and birch are also reported to be attacked, although mainly when growing next to severely defoliated oaks.

Larvae of the oak processionary moth are also a risk to human health. The larvae are clothed in numerous long white silky hairs, but much less evident is the covering of many thousands of much smaller irritant hairs (setae) that contain a toxin. Contact with these small hairs, or their inhalation can result in severe skin irritation and allergic reactions.

Further info can be found on the Forest Research website - |Oak Processionary Moth - Thaumetopoea processionea

A guidance note published by The London Tree Officers Association can be downloaded from here: |Oak Processionary Moth Guidance Note

Please report sightings to the |Forestry Commission or to your |Local Authority.

Address to Contact if You Think You Have Seen This Insect:

Forest Research
Tree Health Division
Alice Holt Lodge
Farnham
Surrey GU10 4LH

Tel: 01420 22255
Fax: 01420 23653
Email: research.info@forestry.gsi.gov.uk

|Below is a list of links to organisations who can provide advice on tree care:

|Forest Research - The Research Agency of the Forestry Commission

|The Arboricultural Association - Useful for registered tree surgeons and consultants

|Tree-care.info - Useful online forum for tree advice

|The Tree Advice Trust - Tree advice

|The Royal Horticultural Society - The UK's leading garden charity