SEMINAR II Part II
(Northern Venue) 26 & 27 May 2005: Fountains Abbey, Ripon, N. Yorkshire.
By Tony Whitehead
Writing as a resident of Ripon, only 2 miles from Fountains Abbey, I am perhaps a little biased in stating what a fine location Fountains Abbey is for holding seminars. The bias of residency notwithstanding, Fountains Abbey is one of the most visited properties within the National Trust portfolio (300,000 visitors a year).
In addition to the 800 year old Abbey the estate has magnificent water gardens including superb temples and follies which wind their way down to the deer park. If you are thinking of a day out at Fountains Abbey I recommend the web site at www.fountainsabbey.org.uk
The seminar was held over two days: The fist day concentrating on principles and the second on practice.
Dr Olaf K Ribeirio
The first speaker to open the seminar was the extraordinarily impressive Dr Olaf K Ribeirio, a plant pathologist of 30 years experience of diagnosing plant health. He is the author of many scientific papers, a worldwide authority on Phytopthora and is owner of the Robeirio Plant Lab inc.
Dr Robeirio’s infectious enthusiasm for the nature of soil and how the soil’s health interacts on tree health carried the audience through a complex analysis of the various components of the soil community and how they interact upon one another to promote tree health or pathology.
Focusing on the nature of soil Dr Ribeirio takes a holistic approach to diagnosis. Aiming to detect root pathogens early and through individual treatment help prevent the loss of the tree. He starts by profiling the soil’s bacterial, fungal, nematode and nutrient levels and from this knowledge he is then able to diagnose and prescribe the corrective cultural procedures.
The techniques of Dr Ribeirio have been practically applied recently in attempts to halt the decline of several trees of high historic value on the Capitol Grounds in Olympia. WA. The actual procedure used included:
- Laboratory analysis of the soil in the root zones of these trees for potential rooting fungus pathogens.
- Diagnosis of any other foliage and branch disorders that might be present
- Analysis of soil nutrients
- Evaluation of the degree of soil compaction
- Excavation of the major anchor roots (where deemed necessary) with an air spade to evaluate any decay that might be present.
Once this data had been correlated procedures were initiated to ameliorate the problem, as follows:
- Treatments for disease problems encountered
- Applying a custom blend of nutrients, microorganisms and mycrrhizae
- Amending soil in the dripline these trees with specific laboratory analyzed composted materials and
- Monitoring irrigation to lessen the risk of re-infections.
The practise described above is both simple and yet still complex. As a general rule Dr Ribeirio’s procedure is to excavate the root plate using an air spade and then to back fill with a composted mulch. However in order for the exercise to be successful, it is necessary to apply the right mulch which has the appropriate organic base. He was not a proponent of woodchip because analysis has established that a mulch with more than 60% woodchip will not reduce Phytopthora infection. In the case of barley straw, if a mulch of barley straw and raw manure is applied without being appropriately composted you will increase the risk of Phytopthora not decrease it.
Dr Ribeirio and friends produce their own mulches with added ameliorants for treating trees. One ameliorant used is Trichoderma. Apparently it is easy to produce your won tricerderma cultures using coffee beans as a substrate.
Fellow American Ed Hayes followed Dr Ribeirio.
Ed Hayes worked for the Minnesota Department of Natural Resources on Forest health for 26 years and now runs his own consultancy practice specializing in tree health and safety. He is the author of the popular field guide “Evaluation Tree Defects” , which is now in its second edition.
Ed covered four subjects in his two presentations:
- Ground Penetrating Radar (GPR) for decay detecting in trees and mapping the structural root systems below the ground
- The Californian Tree Failure Programme
- And the to be introduced International Tree Failure Database
- The Biomechanics of Summer branch drop and the value of failure databases for identifying potential summer branch drop failures
Ed Hayes’ gave informative profile of the current status of GPR. The equipment has been featured in the Newsletter before, and consists of hand held unit which is both the transmitter and the receiver for the radar which links to a laptop computer. For root mapping the equipment is carried in a three wheel cart. At the present moment the TRUTM system is not available with processing software consequently on site the laptop computer is working as a data logger rather than as a processor as per the Picus equipment.
The decay detection in tree trunks is by way of a series of transverse profiles. These profiles are akin to a non-invasive decay detecting drill log. The profiles are not generated on site and are obtained by sending away the site data to the parent or supply company for post processing
The mapping of structural roots is undertaken by walking around the tree with the TRUTM unit in a buggy. Fat anchorage roots appear as a pulse of white light against a black screen.
I had reservations as to how ready for the market this equipment is. The decay detecting traces did not provide a single whole transverse picture of the tree trunk as per the Picus machine and the transverse traces generated by a decay detecting drill are likely to be more accurate and are produced immediately on site. In regard to mapping tree roots, the AA had a presentation in the mid 90s from a company that produces GPR for forensic and archaeological purposes and they were the Company that surveyed west’s garden for further corpses. They advised that GPR does not work well in clay soils or stony soils and that the ideal medium is fine sand or silt. I have reservation as to whether the information at the mid 90s AA conference does not hold true to this day.
Ed Hayes followed his profile of GPR by an analysis of the Californian Tree Failure Report Program which was started in 1987 by Costello and Berry. Costello and Berry collated questionnaires received from arborists on tree failures. The information generated enabled the development of specific tree species failure profiles. The hope is that this database will inform arborists to better evaluate failure probability. Access to the data is available through the website http://groups.ucanr.org/treefail.
In private practice we undertake surveying on a daily basis. However our surveys are normally for a single client with a specific purpose. In the case of designing National surveys, the first question to ask is what questions do you wish to answer?
The CTFRP is limited to the major species in Northern California, San Francisco Bay area. Ed Hayes went on to illustrate how some trees in the database perform differently in different parts of the USA and that the number of species profiled does not necessarily include the major species in other States.
The CTFRP has produced some very interesting information on tree performance and the US forest Service in co-operation with the ISA have developed a similar system that can be used throughout the world. The International Tree Failure Database hopes to build on the CTFRP and produce an international profile of species failure.
Ed Hayes’ second talk gave an in depth profile of summer branch drop. This included an investigation into the causes of summer branch drop from a survey of opinion in the USA, to a thorough round up of the bio mechanics of summer branch drop including the works of such luminaries as Matteck, Shigo etc.
Dr. David Lonsdale is so well known that I doubt he requires introduction. It suffices to say that he was a researcher at Alice Holt. His researches over the years have included ‘Phytopthora of Alder’, Beech Bark Disease’ and ‘Latent Stress Dependent Pathogens in Sap Wood’. He was awarded the AA Prize for Arboriculture in 1999 and is probably best known for his authorship of ‘Principles of Tree hazard Assessment and Management.’ In 2000 he was contracted to re-design the government funded annual survey of non-woodland trees involving volunteers.
Giorgio Catena and Neville Fay (Photo: Andrew Cowan)
Dr Lonsdale gave a thoughtful analysis as to why bother to undertake surveys and to what benefits said survey may bring. He also highlighted the problems of setting down and maintaining standards. It is not until I heard Dr Lonsdale speak did I realise the complexities and difficulties in undertaking National surveys especially with modest funds. In private practice we undertake surveying on a daily basis. However our surveys are normally for a single client with a specific purpose. In the case of designing National surveys, the first question to ask is what questions do you wish to answer?
Because at the end of the day the designer has to come up with a serviceable remit.
David’s solution to standardizing the National Tree Health Survey was to design a questionnaire for the volunteer tree surveyors to answer on each trial plot. The questionnaire has a set of 20 questions ranging from diameter at 1.3m to premature leaf fall. The qualitative questions have a ranking of 0-3. When the volunteers were shown the form apparently many were horrified and the volunteer survey force was greatly reduced. David commented that if the form was found to be so frightening by some of the tree surveyors he questioned the quality of their observations. Despite this David went on to say that the outbreak of virtually all new pathogens in the UK have come to the Forestry Commission’s knowledge due to a concerned member of the public contracting their advisory service.
At first sight Dr Catena’s infrared camera would appear to make all AA registered consultants redundant and all that is necessary is to take one photograph and your decay analysis is in your hand within minutes.
David also profiled the health of woodland surveys undertaken by the Forestry Commission and showed how important they were in determining the rise or fall of exotic pests and the potential effects of changes caused by global warming. He ended on a positive note by showing how successful the FC’s acid rain tree survey was in putting the matter in context.
Dr. Giorgio Catena is a remote sensing, aerial photography and thermal imaging expert. He has written many scientific papers. 40 on tree assessment via using thermography.
Dr Catena gave a presentation at the AA conference 2 years ago and the Treework Environmental Practice seminar gave a welcome opportunity to review this new technology. Infrared photography has been used for many years for failure diagnosis in numerous disciplines. Dr Catena gave two excellent examples: the first was of a shot of overhead powerlines and the cold spot showed identified the faulty connection. The second was of an under floor heating system the broken coils clearly showing up as blue lines in the picture.
Thermography has been used successfully for identifying foliage and canopy disorders – the ailing trees photograping hotter than the healthy trees. Dr Catena gave several examples ranging from the spread of Phytopthora in a woodland to pollution damage.
The system in essence is very quick and easy. You photograph the trunk, or relevant part of the tree, and adjust the temperature control on the cameral to give a contrasting reading. The advantage of this method is it is extraordinarily fast and aerial parts can be inspected from the ground.
At first sight Dr Catena’s infrared camera would appear to make all AA registered consultants redundant and all that is necessary is to take one photograph and your decay analysis is in your hand within minutes. In practise the converse is true and there is a high level of interpretation and it is easy to condemn healthy trees. The camera is not effected by temperature so the time of year is not relevant but it is thrown by foliage. Leaves show up as dark green spots, which if were not compared to an ordinary photograph of the tree could be interpreted as a large area of decay.
The illustrated temperature scale is the standard light spectrum of red being hot through to blue being cold. Decayed or diseased tissue has a lower temperature than healthy tissue. The interpretive or complex part of using the camera is that the scale is relative. That is when viewing the tree through the camera the inspector adjusts the temperature variation scale until the tree is displayed in an appropriate range of colours. The infrared photography is not relative in the terms of a decay detecting drill where the test is relative in that the drill trace is an indirect reading of decay. However in the case of decay detecting drills it is the same test you are applying to every tree. In the case of infrared the surveyor his altering his scale bar until he/she considers it to give a true reading.
Despite my reservations regarding the relativity of the instrument, Dr Catena gave a superb example of quantified monitoring for a parkland tree. The tree had a basal heart rot and he took photographs annually over a period of years. The infrared camera was able to give a superb track of the spread of decay and to show at what point the tree should be removed. Though the Picus is currently the most accurate machine it is relatively slow to set up on large trees and annual monitoring using this device is unlikely to be realistic whereas to take a thermal imaging photograph on an annual basis is not an arduous task.