Technical
Inonothius dryadeus - fungal bracket
An important element to any strategy is having a risk management programme whereby trees will be subject to regular inspection, especially older trees. In order to prepare a meaningful strategy it is important to have a comprehensive inventory of tree resource.
When managing trees on a golf course for risk, certain criteria need to be considered. The landowner has a duty of care under the occupier’s liability act to ensure that anyone entering onto the land is not at risk of injury. Therefore, it is important that trees, or parts of trees that are potential hazards, have been identified and appropriate action is taken.
In the event of an incident, in order to avoid being held legally responsible for that incident, a landowner must be able to prove due diligence and show that all possible and reasonable precautions have been taken, and that proper checks and records were made.
When undertaking a hazard risk assessment, an important consideration is the potential target. Where a tree with defects is located in an area, which is rarely, or occasionally used by golfers or staff, it may be acceptable to retain such a tree which, if it were in an area of frequent use, would warrant immediate felling.
When assessing trees, an understanding of the trees biology and growth habit are important, together with a knowledge of the diseases and defects that are likely to affect them. There are three areas of a tree, which need to be reviewed:
Honey fungus on a stem
1.The roots, root buttresses and lower stem
2.The stem and branch structure
3.The foliage
Each area will have specific issues that may need attention. As trees age, they are more likely to be affected by root and butt rots. These are decay fungi, which are part of the natural environment, which can weaken the structure of the timber in the tree and render it prone to failure. The fungi are often tree species specific. Different fungi have different pathology and, whilst the presence of some fungi can mean the risk of immediate failure, others are very slow degenerating fungi and their presence may not require immediate action. For example, the presence of Ustulinia on beech is usually very serious, whilst Beefsteak fungus on oak is a manageable pathogen. Decay fungi produce brackets, fruiting bodies (mushrooms). These can be annual, and annual brackets are seasonal. Dryads saddle appears in May/June, and Giant Polypore appears in the autumn, late August-October. The brackets can also be perennial, that is they remain on the tree and often increase in size every year.
Being able to recognise each fungal
bracket is important, and appreciating its significance is critical. Field guides such as the Arboricultural Associations publication An Arborists’ Field Guide - Fungi on Trees, is a very useful booklet to identify the various common fungi that cause problems for trees. It is important to examine the base of
trees for basal cavities, wounds on root buttress and movement or cracks in the soil, which can be an indication of root problems even in the absence of fungal brackets. Problems with trees can also manifest themselves on the tree’s stem. Loose bark can be an indication of stem decay. Excessive peeling bark on sycamore can be an indication of Sooty bark disease, however, this observation should be cautioned with the normal bark peeling of a similar species, plane trees. Bleeding cankers, both bacterial and fungal, will produce tarry exudates from the bark, which can be terminal for some species, such as Horse chestnut infected with Pseudomonas syringae pv aesculi. Structural defects may also show up on the stem, such as spiral cracks, increment strips, and buckling and loose bark. Bark creases and cracks are often an indication of internal weakness in the stem.
The presence of ribs on the stem, these
are protrusions on the stem, which are indicative of an internal crack. Pointy- nosed ribs are often more dangerous than snub-nosed ribs. Non-uniform swellings in the stem can be an indication of internal defects and possible failure points. The crown of the tree can also pose
problems, especially in mature trees such as unions, which are points of potential breakage. These are most problematic in maples and beech. Trees which have been previously pruned and that have produced regrowth, which is often multi-stemmed, can be at risk of breakage due to top-
“A tree strategy provides a clear rationale for ensuring that adequate resources are allocated on an ongoing basis”
FEBRUARY/MARCH 2012 PC 107
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