Please find attached a copy of the report relating to your tree. You'll see that it was written in February of this year (and my records indicate that it was also sent at that stage) but, as I was on the verge of a major IT failure around that time, it's possible that my Email programme's record of sent messages is erroneous. I didn't realise that you hadn't received a copy until our recent discussion and your Email below, and I'm sorry that you had such a long wait. I hope you'll find that it answers the need outlined in your message.
Best regards
Steve
Dr Steven Hendry
Forest Pathologist
Forest Research
Northern Research Station
Roslin
Midlothian
EH25 9SY
Condition of mature sycamore located in Cemetery Road, Dalkeith
Background: In June 2014, the Tree Health Diagnostic and Advisory Service of Forest Research received a request from Mr. Gerry Goldwyre & Mrs. Susan Goldwyre to investigate a rapid decline in the condition of a mature sycamore (Acer pseudoplatanus) within the garden of their house in Cemetery Road, Dalkeith. The tree in question, located at an Ordnance Survey grid reference of approximately NT327669, lies close to the boundary between the Goldwyres’ property and land owned by the Dalkeith Lawn Tennis Club immediately to the south. A house built in 2009 is situated several metres to the north of the tree, though building works reportedly took account of impingement upon the tree’s rootplate and no decline in the condition of the tree had been observed in the years following its construction.
The tree is reported to have shown no signs of ill-health in 2013, and not to have appeared unhealthy at the time of bud-burst in mid-April 2014. Shortly after flushing, however, browning and wilting of the foliage occurred over much of the tree’s crown and affected leaves started to be shed thereafter. The condition of the tree in early June 2014 is illustrated in Figure 1, which indicates that more pronounced browning and thinning of the southern side of the crown had occurred at that time.
Figure 1. Condition of the sycamore in Cemetery Lane, Dalkeith on 3rd June 2014. Semi-aerial view taken from the water tower on the opposite side of the road. Photograph provided by Susan Goldwyre.
Site visit and subsequent investigations: A site visit to investigate the possible cause(s) of the tree’s decline was undertaken on 27th June 2014. Activities in the vicinity of the tree were discussed and it was established that no invasive ground works or chemical applications had been carried out within the boundaries of the Goldwyres’ property in the recent past. Whilst herbicides were occasionally used in the garden to control weed growth this was confined to paved areas and did not occur near to the tree in question.
An examination of the bases of the stems and the major surface-lateral roots was undertaken which revealed only the presence of living, healthy bark: no evidence of physical damage or fungal infection at the base of the tree was detected. Inspection of the major limbs of the tree revealed no signs of bark exudation or sunken areas which might have been present if killing of bark on the stem had occurred or was ongoing. Substantial defoliation had occurred throughout the crown of the tree (Figure 2) but was clearly directional in nature with the limbs on the northern side of the tree displaying the best retention of foliage (Figure 3).
Branch samples were obtained from the lower crown of the tree using high pruners and were inspected for signs of xylem staining and bark death on site. Although death of the fine twig structure was evident, and patchy necrosis on small-diameter branches (<5cm) was noted, this was not associated with overt evidence of the presence of a pest or pathogen. The samples were therefore bagged and transported to the laboratory for subsequent microscopic examination.
Figure 2. Condition of the sycamore in Cemetery Lane, Dalkeith on 27th June 2014. Ground view from the same aspect as Figure 1.
Permission to inspect the area to the south of the tree was obtained from Dalkeith Lawn Tennis Club via Mrs Goldwyre and the presence of a recently-created stump which apparently belonged to a sycamore was noted. The stump had been cross-cut in a manner suggesting that herbicide had been applied to the cut surface at the time of its creation to prevent subsequent sprouting of suckers from the root system (Figure 4). The distance from the stump to the boundary with the Goldwyres’ property, and the distance from the boundary to the base of the tree, was measuredusing an open-reel tapemeasure. The distance between the stump and the affected tree was thereby established to be approximately 8 metres.
Figure 3. Condition of the sycamore in Cemetery Lane, Dalkeith on 27th June 2014. Ground view from the north, illustrating foliar retention on the limbs of the tree nearest to the house.
Figure 4. Cross-cut stump located within the grounds of Dalkeith Lawn Tennis Club to the south of the affected tree
The branch samples obtained during the site visit on 27th June 2014 were examined microscopically in the laboratory and isolations made from both the bark and xylem to determine whether infection by a fungal pathogen had occurred. No signs of fungal colonisation were observed on the leaves, shoots, twigs or branches and isolation from both xylem and bark yielded no cultures of plant pathogenic fungi.
Conclusions / recommendations: The speed and pattern of symptom development which was evident on the sycamore located in Cemetery Lane, Dalkeith was only consistent with the actions of a limited range of potential damaging agents:
1. A rapidly developing root pathogen (such as a Phytophthoraspecies) killing the bark in the main roots and at the stem base of the tree, thereby depriving the crown of the necessary resources to survive.
2. A vascular wilt pathogen infecting the conducting wood within the stem & branches, thereby preventing the flow of water from root to crown necessary for the survival of the shoots and foliage.
3. A chemical agent capable of systemic spread, introduced into the tree via its rooting system or at its stem base and subsequently transported by the tree’s vascular system to the shoots and branches, killing these directly.
The first two of these possibilities can be discounted on the basis of the site investigation and subsequent laboratory examinations reported above. No evidence of bark death at the stem base or in the major roots was detected (eliminating possibility 1) and no evidence of a wilt pathogen was found either in the form of xylem staining or via isolations to determine the identity or the fungi associated with dysfunctional bark and wood within the tree (eliminating possibility 2).
Contrastingly, the speed, nature and pattern of symptom development which were noted on the tree in question would all be consistent with damage by a chemical agent capable of being transported within the tree’s vascular system (such as a systemic herbicide). Such an agent could have been introduced into the tree by a variety of routes:
1. Direct injection into cuts or holes in the stem or roots of the tree.
2. Treatment of suckers at the base of the stem or emanating from its roots.
3. Treatment of another tree / stump of the same species sharing a root graft with the affected tree.
No evidence for direct introduction of a chemical into the affected tree was found, though a careful examination for signs of such an introduction were made. Possibilities 2 / 3 are difficult to separate in practice, particularly where the production of suckers from the roots of a large tree, and at some distance from its stem, is a possibility (as is the case with sycamore).
Circumstantial evidence suggesting that possibilities 2 / 3 might apply in this particular case was found in the form of a recently created stump which had been cut in a manner consistent with the application of a herbicide to it. The stump was of the same species as the affected tree (as confirmed by examination of historic photographs showing the tree from which the stump had emanated) and was located on the side of the affected tree which had developed the most severe symptoms. It therefore appears possible that a herbicide was applied to the stump in question and that it was translocated into the rooting system of the affected tree via natural continuity of their vascular systems or via a root graft between them. However, information supplied by Mrs Goldwyre following discussions with Dalkeith Lawn Tennis Club suggest that, although a translocated herbicide (glyphosate) was indeed applied to the aforementioned stump, this action took place after the affected sycamore had started to display symptoms of poor health at the beginning of 2014.
Nevertheless, the symptoms displayed by the sycamore in Cemetery Lane are consistent with damage by a chemical agent capable of being transported within the tree’s vascular system and not with infection by a pathogen: the introduction of such an agent may have occurred via a route which was not uncovered by the site investigation. Chemical analysis of shoots from the affected tree could be undertaken to confirm this diagnosis but would be of little value in the absence of evidence as to the source of the chemical concerned.
Trees may recover from chemical damage if a sufficient quantity of dormant buds are present on their branching structures to promote recovery growth in subsequent years. It is therefore recommended that the tree in Cemetery Lane should be retained until the spring of 2015 (provided that tree safety considerations make this a viable option) and that the extent and vigour of any recovery growth be assessed at that time. Since certain chemical agents influence the form and colouration of foliage produced in the year after the tree’s initial exposure, this action might also serve to provide an indication of the identity of the damaging agent concerned.
Dr Steven Hendry
Forest Pathologist
Forest Research
18th February 2015.
Postscript - Susan Goldwyre
Sorry that the photos don't appear from the report. This is one of the photos, already posted by myself previously when I described what was found on the tennis club ground. The club maintain that they treated this stump after they observed the leaves on our sycamore tree turn brown. The club would not supply a sample of what they applied to the stump. The stump is from a sycamore tree felled without permission, and it is large enough to have required permission. I didn't hear of any action levied against the club for the removal of this tree without permission.
The space, the light and the Katsura tree planted in the new space are wonderful. As is the wood for burning. Almost makes up for the cost of felling. Doesn't compensate one bit though for raising a complaint about an insignificant wood store that cannot be seen by anyone and will cost over £200 for planning permission. Shame the club didn't have to pay £200 for felling a tree w/o permission and probably inadvertently killing off a mature TPOd tree at the same time.
