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Subject: Tree inspection report.
Location: Panthers Wallacia Golf, Wallacia, NSW.
Species: Eucalyptus viminalis.
On Thursday 3rd of February 2011, Geoff Goodwin and myself (Teachers of Arboriculture, Richmond TAFE) inspected several trees on the Panthers Wallacia Golf course site. Panthers Wallacia have kindly allowed us access to this site over the past five (5) years for our students from Richmond TAFE to undertake practical work as part of their studies in the Arboriculture CII and CIII courses. Whilst undertaking the tree inspections, we noticed a large Eucalyptus viminalis located adjacent to the eighteenth (18th) green, which appeared to be in very poor condition, see below for further details.
We have kept this tree (Eucalyptus viminalis) under observation for the past five (5) years, since the first infestation of Winter Bronzing Bug (Thaumasticoridae, see figure 1)) was noticed. It was hoped that the annual use of Merit ® (insecticide) on the adjacent green would aid in the control this insect. Over this period of time the tree has recovered to a certain extent and continued to grow, all be it poorly.
At the time of writing this report, the tree is exhibiting an abundance of epicormic shoot re-growth (see figures 2 & 3); this type of shoot growth is usually an indication that the tree is under stress. Epicormic shoot growth is short term growth and does not have a good attachment to the trunk, much of this growth will fail and the remainder of the epicormic growth that matures may detach and fall from the tree without warning, due to the poor attachment.
Figure 2. Figure 3.
All of last seasons shoot tips have died off after defoliation and the tree is presenting a large amount of dead wood as a result.
On closer inspection there is also significant proof of decay throughout the trunk, which can be evidenced by the ?? Bracket Fungi fruiting bodies (see figure 4, 5, 6, 7 & 8). There is also significant decay at the base of tree on the north east side and when sounded out there appears to be a large void/hollow forming, this hollow does not bode well for the long term stability of the tree, posing an OH&S risk to passers by.
Figure 4. Figure 5.
Figure 6. Figure 7.
When all these factors are put together along with the age of the tree and the cultural practices, which take place in the surrounding areas, the prognosis for the tree in question is poor.
The family Thaumastocoris has had a devastating impact on many Eucalypt species in the Sydney metropolitan area. The host range of this bug has increased from two eucalypt species, Eucalyptus scoparia and Eucalyptus nicholii, to other common Eucalypts through Sydney’s urban forest.
The symptom of infestation is so widespread it has a common name “winter bronzing” due to the red-yellowing of the leaves within the cooler months followed by leaf drop. Severely infested trees are usually removed unless early detection and early treatment is implemented.
The adult Thaumastocoris insects are 2mm long and pale brown in colour (see figure 1), with a distinctive ‘X’ on the upper body. The bugs feed by inserting their sharp, tube-like mouthparts into the plant stem and sucking out the sap. The plants lose water and nutrients, becoming paler in leaf colour and defoliating, this inturn reduces the trees ability to produce food and go through the normal processes which enable the tree to recover from insect and other damage. Add to this the age of the tree and the long period of drought that occurred over the past years, and the health and vigour of the tree has declined significantly.
Unlike other native species of insects, which infest Eucalypts annually or seasonally, this insect colonises the host tree and does not alight with the changes of the season, much to the detriment of tree.
When all the factors are taken into account, the only recommendation which can be considered is the removal of the tree as soon as possible.
I am recommending the removal of all major branches above the first major fork in the trunk and creating a habitat for native fauna of the area (see figure 5).
The removal of the branching from the top of the tree will remove an enormous amount weight from the top of the tree and assist with the long-term stability of the structure. The retention of the structure will still then be able to play a part in the golf course as an obstacle.
I would also recommend that the remaining structure be inspected annually to monitor the decay which is already present.
If you require any further information or further explanation, please do not hesitate to give me a call.