Technical
Giant Polypore
heaviness or end loading. Remedial solutions may include restorative pruning or, in extreme cases, felling. Trees with a dense branch structure can have rubbing/crossing branches which are weakened and at risk of breakage. As trees age, branches start to sink, this can be observed as gaps appear in the canopy. Sinking branches can be at risk of failure. Options for remedial action can include branch reduction or cable supports.
The foliage in the canopy of trees can often be an early indication of serious problems. Reduced leaf size, or leaf density, can be indicative of root and systemic problems. Trees will often suffer from aesthetic foliage problems such as Guignardia leaf blotch of Horse chestnut, Tar spot on sycamore or a more debilitating foliar disease, such as blossom wilt of cherry. As mature trees decline they start to
retrench, that is, the distal parts of the canopy are shut down. This manifests itself as crown die back. This can be a very obvious early indication of tree decline, especially during the summer months.
Ganoderma resinaceum - fungal bracket Trees can also go into decline as a
result of non-pathogens. Trees struck by lightning will have bark cracks and localised area of crown die back. Chemical damage from herbicide spray will cause foliage die back. Insect damage is not generally a serious problem, especially when there are cold winters. However, during mild winters, insect populations can build up in sufficient numbers to cause foliage problems; conifers are more at risk, for obvious reasons. In the past, problems with cypress and spruce aphids have been significant.
Solutions
Once potential serious defects are identified, a management solution needs to be considered. One option is to move the target. This may involve restricting the public from the area or closing part of the course during periods of extreme weather. Remedial tree works should be considered; this may include branch removal, crown reduction and lateral branch reduction, and supporting weak branches with cables or braces. Trees, which have suffered root compaction, can
have the ground decompacted with an air spade, and then mulched, which can help restore root vigour and reverse decline. All remedial tree works should be carried out in accordance with BS3998: 2010. Trees which are in decline or may, in fact, be dead or dying, have a very important part to play in the environment. Where possible, deadwood should be left in trees for invertebrates, and, where possible, dead standing trees should be maintained. These can be cut back to ‘hat stands’ or poles as appropriate, as they provide habitat for invertebrates, bats, birds and potential feeding and nesting habitats. Not to forget hunting and plucking perches for birds of prey. Before embarking on a dramatic solution, which may include felling, specialist advice should be obtained from a suitably qualified and competent arboricultural consultant. More information at
www.trees.org.uk
This article first appeared in Greenside magazine, the official publication of the GCSAI. www.
gcsai.org
Split stem at weak union 108 PC FEBRUARY/MARCH 2012
“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-heaviness or end loading”
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