As an arboricultural consultant, I get asked all sorts of question whilst carrying out my varied work. The most common question this year is about problems with Horse Chestnuts. They are now affected by three conditions, Bleeding Canker, Leaf Blotch and Leaf Miner. Put all these together and you have trees under stress that will probably die in the near future.
Sudden Oak death is affecting other species including Beech, Sweet Chestnut, Rhododendron and Viburnum. Symptoms on tree trunks are the presence of dark red to black sap oozing from the bark and, as the disease spreads, girdles the trunk causing rapid death. In shrubs, likely symptoms are dying foliage and damage to stems.
A similar disease affecting Alder around the UK is causing dieback, and this can be seen around lakes and along riverbanks. It spreads rapidly and the only methods of control appear to be hygiene - removing and burning the affected tree - or heavy coppicing. More information can be found on the forestry commission web pages www.forestry.gov.uk.
Cures are going to be difficult, or nigh on impossible, to find, and hygiene may be the only choice. In my view, this really shows how important it is to have a diverse tree population in age and species. Avoiding species that are prone to infection in new planting is also advisable. We do have to ask ourselves if this proliferation of tree diseases is a result of climate change?
Are your trees safe?
The picture here, taken last autumn in Cheltenham, needs no explanation, and the occupant of the car was very lucky to escape without serious injury whilst on the way to church. Had the tree undergone regular inspection this accident may have been avoided but, even so, trees do sometimes fail for no apparent reason. I have seen similar incidents in the past, where people have been killed, that certainly could have been avoided.
Recent legal cases reaching the High Court have resulted in some clarification over inspection and what level of qualification is required. This has resulted in an almost panic situation by tree owners, either starting to lop or fell trees for no good reason.
All owners of trees have a 'Duty of Care' to ensure damage to life and property is kept to a minimum. If you have trees on your sportsfields or estate, it is important to keep an eye on them with regular inspections, especially where a number of people are near the trees.
The Heath and Safety Executive (HSE) Management of Risk from Falling Trees is a useful document that should be read by all grounds managers with responsibilities for trees. The HSE have produced a short document offering advice, which can be found at www.hse.gov.uk.
Michael Ellison of QTRA Tree Safety Management has developed a Quantified Tree Risk Assessment (QTRA), that is becoming an accepted system, and a number of trained licensed users can be found around the UK.
For a tree-failure hazard to exist, two criteria must be fulfilled. There must be potential for failure of the tree, and potential for injury or damage to result. The tree owner, or manager, needs to consider the likelihood of a combination of tree failure, people and property, resulting in harm, and the likely severity of the harm.
The system enables tree assessors to allocate numerical estimates of risk, which can be compared with a generally accepted level of risk. There are three components of QTRA - 1) target; 2) impact potential and 3) probability of failure. The product of these component probabilities is referred to as the 'Risk of Significant Harm'. More details can be found at www.qtra.co.uk.
An estate manager now has two choices when inspecting his trees. He either becomes qualified, or has to use a qualified tree inspector.
LANTRA Awards, the sector's skills council, has created two qualifications for tree inspection through the Arboricultural Association:
1. Basic Tree Survey and Inspection
This course is a one day Lantra Awards course aimed at providing specific tree survey and inspection training at a basic level for contractors, highway engineers, tree wardens, grounds maintenance staff, rangers and other persons of a non-arboricultural background or with limited arboricultural knowledge.
The course teaches them to identify obvious defects from ground level, and then to report their findings to a line manager. There is no assessment at the end of the day.
2. Professional Tree Inspection
A three day course that provides specific tree inspection training at an advanced level, for competent arboriculturists to enable them to identify defects from ground level, from a climbed inspection, or an inspection aided by the use of a Mobile Elevated Working Platform (MEWP).
The course provides training in how to specify the necessary remedial works and record the inspection process. This then forms part of a defensible system. At the end of the course, candidates undertake a competence based assessment directly related to tree inspection.
This qualification is being specified by many public authorities for arboricultural consultants carrying out inspections.
Tree Preservation Orders
Want to carry out tree surgery or simply fell a few? Take care, they may be subject to a Tree Preservation Order (TPO) applied by your local planning authority. If you are not sure always check.
Another way trees are preserved is if you are in a conservation area. You need to notify the planning authority of any work you wish to undertake by giving six weeks notice. My advice is always to talk to your local tree officer on a regular basis to sort out the problems before they occur.
From the 1st October 2008 the new TPO regulations came into force. These introduced a standard application form for work on protected trees, and a fast track appeals system.
The forms are readily available on your local council website, usually in the planning section. Fill out the form with details of the work planned and either a plan or sketch of the site. If permission is refused, there is an option to appeal (at no cost) which usually results in a site inspection by a government inspector before a final decision is made.
Useful Web pages:
For land training qualifications www.lantra.co.uk
Arboriculture Information Exchange www.aie.org.uk
The Arboricultural Association (AA), who set out to raise standards and research in the industry, offer a number of training courses at different levels. www.trees.org.uk
Quantified Tree Risk Assessment (QTRA) www.qtra.co.uk
Forestry Commission www.forestry.gov.uk
Phillip Ellis. Email: email@example.com