PJC Consultancy

Spring Brings New Wave of Tree Failures

timh — Mon, 14 May 2012 08:00:39 +0000

The recent heavy rain and strong winds have brought a number of trees to the ground. Heavy rain can saturate the ground, reducing the ability of tree roots to maintain stability and keep the tree upright. High winds can then cause the tree to fail. Trees with newly flushed canopies are particularly susceptible to wind throw, as the canopy acts as a sail increasing the load on the tree’s roots. This kind of tree failure can be impossible to predict which makes it all the more dangerous. The tree below was spotted whilst out and about and poses a serious danger to people using the public highway.

Windblown tree over public highway

Beetle Alert in Kent

timh — Mon, 30 Apr 2012 09:14:06 +0000

A new threat to the UK’s trees has been found at Paddock Wood in Kent. The larvae of the Asian long horned beetle have been found in Poplar trees adjacent to a yard importing stone from China. The beetles are thought to have travelled in wooden packaging used to import the stone. The beetle is a significant threat to forestry as it has the potential to kill large numbers of trees and reproduce rapidly.

Eradication measures will be implemented to prevent the spread of the species, to include felling of trees surrounding the source of the original infestation. The forestry commission is urging anyone who thinks they may have seen an Asian long horned beetle to contact them immediately.

Asian long horned beetle

British Standards Institute Launches Revised Guidance

timh — Tue, 17 Apr 2012 16:45:49 +0000

The British Standards Institute (BSI) has launched their revised document, BS5837:2012 ‘Trees in Relation to Construction - Recommendations’. This is the document used to assess trees on construction and development sites and their influence and constraints on design. It is the industry standard used by all Local Authority Planning Departments, and helps define the planning process. All arboricultural consultants will have to update their reports and working practices to comply with the latest guidance.

Trees in the Wider Landscape

National Tree Safety Group Publish New Guidance

timh — Thu, 12 Apr 2012 13:16:34 +0000

The National Tree Safety Group published their long awaited guidance document at the start of this year. It is slowly circulating and being adopted by a number of tree and landowners forming part of their tree management strategy. You can view two sumaries or download the entire document from either the NTSG or Forestry Commissions website. If you are a tree owner you should check out the guidance to see how it relates to you. A second set of guidelines that may be more prescriptive is being prepared by the British Standards Institute, and should be released soon.

Inspecting trees as part of a tree survey

New Wave of Phytopthora Threatens UK Trees

timh — Mon, 26 Mar 2012 15:33:22 +0000

An outbreak of a new strain of Phytopthora, (Phytopthora austrocedrae) has been identified as affecting the native conifer Juniper at two sites in Scotland. This new strain is damaging to the UK’s native confier population as little is known about its growth habit and spread. It also has the potential to infect Lawson cypress, a common ornamental species planted in UK gardens. Lawson cypress has already been hit by other forms of Phytopthora which leads to foliage browning and eventual death.

If you suspect that Phytopthora may be affecting your trees you can find further info on the Forestry Commissions website under Plant Health.

Phytopthora Affecting Lawson Cypress

Sycamore Tar Spot

timh — Mon, 12 Mar 2012 09:31:42 +0000

Rhytisma acerinum, commonly known as sycamore tar spot, can be seen on trees throughout the country. During the summer, Rhytisma acerinum manifests itself as raised black spots on the leaves of sycamore trees. Although slightly detrimental to the aesthetics of the tree, this fungal infection does not have any significant affect on the health of established specimens.

The black spots found on the leaves are the fungal fruiting bodies. When the leaves fall in the autumn, the fungus continues to live in the foliage detritus on the ground. Airborne spores are released from the fungus in the detritus during the spring, and attach themselves to new leaves and the life cycle continues.

To reduce the affects of infection, removing fallen leaves from the vicinity of the tree and burning them will kill the fungus as it over winters. This method will only reduce the level of infection. To completely eradicate the infection, all sycamore leaves would need to be removed from the area surrounding the tree, which of course would be almost impossible. The airborne spores can after all travel as far as the wind blows!

Sycamore Tar Spot on Leaf

Trees and Safety – A Good Example of Risk Management

timh — Tue, 06 Mar 2012 09:01:09 +0000

Taking a break from our regular series on tree health this week we look at tree safety and public access in the countryside. Whilst people visiting the countryside must accept a level of risk, blatant hazards can be removed or reduced. The pictures below illustrate how annual surveys of rights of way can remove unacceptable hazards. The tree was dead, with the top snapped out and resting precariously over a well used long distance path, the Saxon Shore Way in Kent. In falling the large limb had knocked over the footpath sign which is seen resting against the tree’s stem. The tree was marked and recorded for urgent removal.

Unacceptable hazard

Nectria Canker

timh — Tue, 14 Feb 2012 10:52:33 +0000

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

Knole Park Bat Box Installation

timh — Thu, 09 Feb 2012 15:06:48 +0000

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.

Fatal Fungus

timh — Mon, 06 Feb 2012 16:58:45 +0000

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