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Nectria Canker
February 14, 2012 by timh
Nectria canker is a fungal infection that is relatively common throughout the UK. It does not always have a significant affect on trees, particularly larger specimens, but can lower the aesthetic value of a tree. It is identifiable by dead branches or branches with wilted or dead leaves but is most easily identified by large cankers, usually found at the bases of dead twigs.

Nectria cankers can be seen on a variety of broadleaf species but coniferous trees are immune. The fungus, spread by wind or rain, can enter a tree through pruning wounds, natural bark wounds or even through leaf scars (where leaves have fallen in the autumn). It can kill small patches of bark, potentially killing small branches, and may form lesions. These lesions grow during the summer months and die back during the winter months, causing the cankers to form and enlarge over time.

Infection can be controlled by use of fungicides but these are usually only used on fruit trees in orchards. Infection can reduce timber value and lower the visual amenity but on larger trees it will not have a significant affect on tree physiology.

Nectria canker on ash saplings

Category: Arboriculture, Consultancy, Tree death symptoms and causes, Tree Knowledge
Knole Park Bat Box Installation
February 9, 2012 by timh
Knole Park, in Sevenoaks, is one of the few remaining Tudor deer parks to have survived the mass development of our countries landscapes over the past 500 years. The park has seen change over the years; in recent history the park lost nearly 70% of its trees in the great storm of October 1987.

Thankfully, there are still lots of impressive mature trees to behold within the park, trees suitable for the installation of bat hibernation roost boxes.

PJC were commissioned to undertake bat surveys on one of the keeper’s cottages on site that had been ear marked for renovation. The surveys revealed that the building did in fact contain a summer transitional roost at one end of the roof void. The species PJC ecologists identified to be using the roost included Brown long-eared bats (Plecotus auritis), Common Pipistrelles (Pipistrellus pipistrellus) and Natterer’s bats (Myotis nattereri).

As part of the extensive mitigation strategy designed by PJC, a hibernation roost bat box was to be installed within the woodland directly adjacent to the cottage. In conjunction with PJC’s sister company PJ Chaffin Ltd the day of installation was upon us. With the aid one of PJ Chaffin’s experienced tree climbers, Sam Taylor, the sturdy bat box was hoisted high into the tree chosen by PJC ecologist Tom Rothero.

With a bit of jostling and, “no the other left” the hibernation box was firmly secured with a south facing aspect out across the deer park. Sam then descended from the tree via his web of ropes after creating much hysteria from nearby power walkers, “Oh look, a man up a tree!” one woman exclaimed. Another successful step towards bat conservation in the south east had been completed.

Category: Uncategorized
Fatal Fungus
February 6, 2012 by timh
Following on from last weeks tree knowledge post, this week we focus on Kretzschmaria deusta, (previously known as Ustilina deusta). This is a particularly dangerous type of decay fungus. It is relatively common, reproducing with spores carried in the wind and can infect most species of tree.

Kretzschmaria deusta is dangerous for two main reasons. Firstly it attacks live trees. It decays the base of the tree, attacking the heartwood. This can often make the extent of decay within the tree difficult or impossible to identify. It can potentially cause stem failure without warning, particularly if the fruiting body has not been identified.

The second reason Kretzschmaria deusta is particular dangerous is because the fruiting body is difficult to spot. It is not an obvious fungal bracket. It instead grows first a white layer at the base of the tree when juvenile, then transforming into a black layer when mature. It can often look like a thin tar covering at the base of the tree. As the fruiting body only grows at the base of the tree, it can often be hidden by long grass, weeds or other plants within a dense understorey. This is one reason you may see experienced tree consultants kicking undergrowth away from the base of trees when carrying out an inspection.

As Kretzschmaria deusta can cause tree failure without warning, infected trees are often condemned as soon as the fungus has been identified, particularly if the tree is in a high risk location such as at a roadside or adjacent to a building. There is no cure for the infection and it can continue living on dead tree stumps after the rest of the tree has been removed. This makes controlling the disease difficult and we must instead be vigilant to spot infection before serious harm is caused.

Kretzsmaria within stem union

Category: Aboricultural services, Arboriculture, Consultancy, Tree death symptoms and causes, Tree Knowledge
A New Series Starting This Year
January 23, 2012 by timh
With the start of the New Year we are starting a new series of blogs on tree knowledge. This will mainly feature on causes of ill health in trees and will help you identify when further action is required.

Giant polypore, botanical name Meripilus giganteus, is a large bracket fungus, which usually affects beech trees. Its impressive fruiting bodies appear around the base of the tree as this fungus attacks the roots. It is parasitic, meaning it attacks live trees, and can cause trees to collapse in the worst instance.

Giant polypore causes what is known as white-rot. This means it degrades and feeds on both lignin (the substance which makes plants woody) and cellulose (cell walls). Its fruiting bodies (fungal brackets) only survive for a year, and may not form every year. The fruiting body is just one part of the fungus. If the fruiting body is not visible, this does not mean the infection is not present, just as removing the bracket will not stop infection.

Giant polypore usually affects the underside of tree roots. This makes the extent of infection very difficult to ascertain. The severity of infection does not always have a visual affect on the crown of the tree either. For these reasons, it is often unwise to keep an affected tree if it is in falling distance of public or property.

Tree failure as a result of infection by Giant polypore

Category: Arboriculture, Consultancy, Tree death symptoms and causes, Tree Knowledge
Recent Storm Cause Chaos
January 9, 2012 by timh
The recent high winds have highlighted the dangers trees can cause when they fall. Numerous roads and railways were closed or disrupted, and the death of a man in Royal Tunbridge Wells was also reported when a tree fell on his van. Trees can fail in high winds in numerous and unpredictable ways, and can cause disruption when this occurs. The photos below show a road on the Romney Marsh in Kent that was closed for five days due to the large number of trees blocking the road.

Fallen trees close road

Fallen tress also brought down overhead services

Category: Aboricultural services, Arboriculture, Consultancy, Tree death symptoms and causes, Tree Knowledge
New Threats to the UK’s Tree Stock
December 6, 2011 by timh
A number of new pests and disease have been identified as affecting UK trees in the past few years, with more on the horizon. Most people will have spotted the defoliation caused by leaf miner moth on our horse chestnut trees. Various species of bleeding canker have also been reported affecting horse chestnut, oak, lawson cypress and larch. This can cause dieback of the foliage and eventual death of the trees depending on the strain infecting the tree. The Forestry Commission have been actively felling affected trees in the south west to prevent the spread which seems to be preventing widespread further infection.

A new potential threat is the potential arrival of the pine processionary moth. This is moving up from its usual home in southern europe with one theory on its migration being linked to global warming. If it arrives in the UK it could devastate the countries pine population. The hairs on the caterpillars body are extremely irritant. The oak processionary moth has already made it to the UK, and is the subject of a control operation. It is harmful to humans rather trees, with its hairs causing extreme irritation which can lead to hospitalisation in some cases.

Further information on the above can be found on the Forestry Commissions website, along with contact details should you think there is an outbreak near you.

Pine processionary moth on the move

Category: Uncategorized
Room for All – Bats and Loft Conversions
December 5, 2011 by timh
We have been involved in many projects that required licencing and mitigation for development especially involving bats. Many of these projects are complex and require careful consideration of factors such as: species present, the ecology and behaviour of that species and designing mitigation that in our opinion, has the most likely chance of being utilised by that species. Therefore, last week we were happy to see the successful outcome of one of our projects.

We carried out a follow up survey for a licensable project involving a loft conversion at a family home. Originally, the type of roost present within the roof of the house was a brown long-eared maternity roost and an occasional summer roost. We had designed for an area of the roof to be retained as a “Bat Room” (with bespoke ‘bat door’ see photo) and transferred droppings on insulation to the garage roof void where there had previously had a small number of droppings present. On visiting the family home on completion of the works, we found signs that bats had used the “Bat Room” over the summer months with large new piles of droppings present in several locations. The garage roof void was inspected and the number of new droppings was found to have increased throughout. Both showed signs of being used by several bats recently. Therefore was classed as being successful!

The specially designed bat door

Fresh droppings - success!

Category: UncategorizedTags: bat mitigation, brown long eared bats, license works, loft conversion, maternity roost |
A New Approach to Tree Risk Management
November 30, 2011 by timh
Whilst out surveying our arboriculturalists spotted this sign. It represents a new approach to managing risk from trees, alerting the public to potential tree failure! We are not sure how effective this management strategy is or how it would stand up in court if damage or harm was caused to people or property.

An effective measure?

Category: Aboricultural services, Arboriculture, Consultancy, Tree Knowledge
Why We Inspect Trees – Part 2
November 22, 2011 by timh
Whilst out on the road our surveyors spotted a tree that had suffered structural failure and was leaning over a heavily used A road. Closer inspection showed the tree had been previously coppiced and decay had set in within the coppice stool, a common occurrence. The local area highways office was contacted, and the threat logged. Unfortunately the tree was sited on third party land and couldn’t be taken down straight away. The landowner was served with a 21 day notice to deal with the tree, which they promptly did.

Regular inspection of trees on your land can highlight tree defects before they can become a threat. Trees next to the public highway, surrounding properties and areas of high public usage should be surveyed on a regular basis to satisfy the duty of care as described by the Homeowners and Occupiers Act.

Failed coppice stool

Failed tree hanging over road

Category: Aboricultural services, Arboriculture, Consultancy, Tree death symptoms and causes, Tree Knowledge
Tree Pollarding – An Ancient Art
November 8, 2011 by timh
Tree pollarding is common practice throughout the UK. It is a method of tree pruning that is often employed to prolong the safe life expectancy of high value trees or to limit their potential size in confined spaces. The practice involves the removal of the majority of the trees crown. Pollarding is only appropriate on certain species of trees, as less vigorous species will not produce re-growth. Vigorous, fast growing species such as willow or poplar react best to heavy reductions or pollarding.

Pollarding a tree removes all of the foliage from the tree, effectively stopping the process of transpiration. This significantly reduces water uptake of the tree, which can in some cases reduce subsidence of nearby buildings or structures. It is only a short-term solution to subsidence as the tree will re-grow and the process of transpiration will begin again.

The points to which branches are pollarded, and where the majority of new growth stems from, will produce ‘muscle wood’ and eventually form ‘knuckles’. It is possible for these points to be subject to decay, although the decay is not always visible externally. If the trees are left for many years after pollarding without re-pruning, the pollard points can potentially fail. For this reason, pollarded trees need a system of cyclical pruning to be implemented. The rate of re-pruning will depend on the size, location and species of the tree.

Pollarding a tree that has become too large for its location, such as a crowded urban area, will allow its retention. However planting a suitable species in an appropriate location should always be the aim of urban planners. Pollarding a tree with a relatively minor stem defect will reduce the ‘sail area’ of the tree as well as the weight on the stem, therefore prolonging its safe retention.

One of the most appropriate uses for pollarding is the safe management of veteran trees. These are trees that have often past their species usual life expectancy, and possess exceptional landscape, historical, cultural or ecological value. Veteran trees are not usually tidy trees. They possess snapped branches, deadwood and decay pockets, all of which can be valuable to wildlife. Pollarding a veteran tree increases its safety and if correct pruning cuts are used, pollarding can accentuate the trees benefit as a wildlife habitat.

Tree operations to produce a pollard

Category: Aboricultural services, Arboriculture, Consultancy, Tree Knowledge

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