Assessing Fungal Decay

Sean Freeman

What I would like to do is use this thread to stimulate thoughts in all of you as to just how you go about assessing (where visually present) fungal decay in trees you are asked to look at/work on.

Its not about how clever I am, or Ekka is, its about looking at some visual examples and talking through what each of us thinks about different approaches. If you don't want to post a response fine but at least think through what is being discussed and how you might have approached it and why.

(Some of the photos I'll use are from a while back and one or two may have been posted in other threads)

The first case study is of a mango Mangofera indica groing in a fence line at a kindy next to a main street that has very high volume traffic usage. The tree is approx 50-60yrs old, 13m high with an asymmetrical spread of 11m. I was conducting a base line audit of the trees in this school for a tree management plan.



At the base of the tree where the ground level meets the bark was a small fruiting body of the fungi Ganoderma sp


Here's a better shot also showing a classic depression in the stem spreading up from the ground in the shape of a rough triangle.




So sounding the stem also confirms the same conclusion altered state in the wood tissues in the indicated area.

We know Ganoderma is a fairly agressive root rot fungi, so strongly suspect that the root system on the knidy side will have been compromised. The root system on the footpath and road side certainly has been!

The tree is providing substantial valuable shade to the grassed playground of the kindy area, but this also means that very high value targets are present under the canopy of this tree as well.

Now remember schools have slightly more capital resources than private tree owners (generally!) and have a much higher commitment to the Health and Safety of those under the canopies.......so given that we have no resistograph, and I have no faith in pico's our next logical step is to do a root crown inspection to assess just how much of the root system has been compromised.

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Sean Freeman

Couple of added points Mangofera is a very effective compartmentaliser, one of the most resiliant trees I've come across when it comes to surviving lopping long term. This mango is growing under the dominant canopy of an adjacent raintree Albizia saman.

Sean Freeman

Using a home made air knife with a trailer mounted compressor we did the root crown inspection.


Almost straight away we found older fruiting bodies that had become buried under grass clippings and slight soil grade changes over a number of years, this fungal decay has been going on for quite some time in this tree.


As the excavation continued we became more and more aware of the extent of the decay and the ease at which the hand saw goes into the stem 300mm is certainly a worry!



Now you could argue why not do the saw into the tree test before all the expense of the air excavation, and I'd have to admit I should have! I just didn't think the decay as quite that bad until the soil started to be removed, lesson....always have a probe of some sort to carry out this kind of simple test, the same probe for finding the root crown in fact.

If you had the probe clearly striped black and white in 10mm intervals it could also be used as a scale indicator in pics (three tools in one!)

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Sean Freeman

So how much of the root system on the kindy side was lost to the Ganoderma sp?

Well in these shots you can see very clearly one main buttress in the centre totally lost to decay, less clear is the decay in the other two outer buttress roots (yellow circles), another point of interest is the adventitous roots (orange arrow) put out by the tree in an attempt ot resetablish function on this side, another VTA indicator to be aware of, all tree species do this to varing degrees dependant on the extent of the decline (ie if they have enough time and energy reserves!) The original fruiting body site is shown by the red circle.




So we now had a great deal more certainty in advising the school that this tree despite its species resiliance to lopping did indeed have so much root and stem tissue compromised by the Ganoderma sp to make retention unacceptable...based on the targets present (if it were in a paddock somewhere with no target..no problem)

Here's the diagrams I used to convey the situation:





The outcome was not surprisingly the removal of the tree.....

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Sean Freeman

So lets look at the autopsy of this mango tree, and compare it to what you might have had in your minds from the beginning.





And the final low stump cross section


Some interesting boundaries in that one! Remember the greatest problem for this tree despite appearances from those pics is not the failure of the stem, there was plenty of solid new timber there....no for me the issue is the loss of buttress roots on the only side of the tree unaffected by the footpath and kerb and road damage all on the other side. The high value targets make any assessed problems far more significant than would be the case in another tree.

But remember the first pics of the small fruiting body, except for the depression in the stem there was no other visual indicator above ground, the canopy of the tree was pretty much normal for a Mangofera in such a street environment.


Without doubt the automatic irrigation system with a popup sprinkler near to the stem increased the propensity for fungal growth to progress rapidly...for us Ganoderma australe, G. lucidium, G. applanantum, Phellinus igniarius are our worst root and stem problem fungi. We take great care with our tree inspections to follow a systematic approach to recording all visible indicators trying to ensure that in the trees we look at we won't miss even the smallest sign, helped by the fact that serious fungal decay in our tree species is almost always indicated in more than one way.

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Eric Frei

See Boa

Things are different down here.

This customer had exactly the same problem, waited till the decay was well and truly done, mango tree fell over smashing the fence and he claimed it on insurance.

And the insurance company doesn't care just pays out.

But in the essence of your thread I tap, look for fruiting bodies and have a really long drill bit I use in my ryobi

PS: Notice the VTA signs of the foliage!

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Sean Freeman

Well, you gave us some pics of failure at the stem there...and certainly looked like Ganoderma sp in the last pic too.

By the time you have lost so much functional tissue strength to lead to failure like that you would certainly expect to have many VTA signals to alert you of imminent doom. That tree of yours I would describe as fecked...meaning so clearly beyond the point of recovery that even someone who has no Arb training or understanding would recognise there is a major problem..we've all seen fecked trees.

Here are some of the VTA signals i would classify as being in the realm of being fecked.....

The production of roots from under the bark (lifting off and dead) in a sheet extending beyond 20% of the circumference of the stem


The dieback of over 50% of the canopy of the tree


Stem cankers evident in current and past fruiting bodies around the entire circumference of the stem.


Close up


Same species of Euc, different canker through the base of the tree


Closer look


The point being when you have these sorts of slap you in the face indicators, if there is any significant target present removal has to be the number one option.

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TrevMcRev

Excellent thread start boa. Look forward to what unfolds in here.

Eric Frei

Boa

I found the pics I took 19th March 2006 of the Jacaranda in New Farm park I reported to BCC.

Look at the canopy compared to the others.

Note the fruiting bodies all around.

Note the mulch, new path etc.

Two were removed, that one and one next to it further west. Pity I didn't take an avenue shot.

I'll have to link this post to the New Farm Jacarandas thread.

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Eric Frei

This is a pic of where BCC made gutter repairs and ground away a poinciancas roots to accomodate.

Site is out the front of 19 Lonsdale st Ascot

Pic was taken 24th March 2006 and reported to BCC, I should cruise past some day and see how it's going. Pretty easy to see the fruiting bodies on this one, but I didn't drill it.

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Sean Freeman

Great pics Ekka, and a great find considering the recent events there..again clear VTA indicators of severe problems high value targets yet little action. But lets focus on the fungal decay, maybe drawing a long bow but I can convince myself I see a depression in the stem above the fruiting bodies, looks like Ganoderma sp to me too.





So what action if the council had been proactive enough? For me root crown inspection, its cheap quick and answers nearly all your questions. When you know the id of the fungi you can apply your knowledge and understanding and experience as to how this particular fungi interacts with this species, combine the environmental factors, the current health and vigor and really begin to be able to predict with confidence what the possible outcomes will be.

They really are great shots mate! They tell a very different story to the one in the media.

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Sean Freeman

Trees growing almost against the road kerbing are always a concern, since we know that they will have massive injuries to 50% and more of their structural roots, it is almost certain that at some point down the track these trees will be colonised by fungi.

In Ekka's pics you can see clearly where the replacement kerbing set back was, how all the roots were severed, torn and fractured providing ideal infection courts for any latent spores that might be present. You can also see where the fruiting bodies suggest advancing decay in structural roots on the other sides of the stem....very serious indeed



Roots growing very near or non the soil surface as many do, have a classic form to them radial growth is restricted in the soil itself and the physical action of supporting the tree resisting wind loading forces leads to this form. Here's a very simplified diagram



When a root rot fungi colonises and consumes the wood tissues (allowing for the different preferences in fungi for cellulose, lignin etc...simplified again) the decay tends to follow the same pattern leaving behind what appears on the surface to be solid timber, but is not.



This can be very simply and quickly detected by the use of a nylon or wooden mallet...sounding the roots, the tell tale hollow ring is unmistakable.

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Sean Freeman

Here's another example of a fecked tree this one is in Innisfail Anzac Park, I have to suspect that the tree Peltophorum pterocarpum was in a right state even before cyclone Larry, but of course the cyclone has made matters worse. Yes I'm writing a letter to Johnstone Shire Council strongly suggesting they should remove this one!





There at least 3 different fungi fruiting on this sad tree!


The fungi for those of you interested are Auricularia sp, Crepidotus sp and our friend in the woods Ganoderma sp

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Eric Frei

I was thinking that was one of Newguy's tree pics of the crapiest trees around. That's a shocker.

Good pics though, ganoderma is most predominant.

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Sean Freeman

I'm guessing that with everything else going on up there that trees in public places like the Anzac park that were not blown apart by the storm have been put on the back burner...understandably.

Sean Freeman

Ok, so far I've shown examples of trees that predominantly have been fecked, and in that probably don't require much thought or prolonged agonising over what course of action to take.....ie if target present remove!

Lets widen the scope of thought somewhat and look at cankers, and what assessment steps I go through when confronted by trees with stem and branch cankers. Again this is not a crash course in mycology so please allow for some simplification and generalisation here, if you think I'm missing something please raise it.

For me in the Northern part of the state there are two fungi that pose significant problems for both native and exotic trees as cankers..Phellinus sp and our friend again Ganaderma sp, its interesting that both these fungi act as fairly straight forward root rot fungi but also have species in their respective genus that survive in the wood tissues as cankers.

When I first started getting interested in fungal cankers it began to become clear to me that the spores of these fungi (like bacteria and other fungal spores) are ever present on the bark of the trees I see, in fact many of the visible features in trees of all ages that I had thought to be insect pests or unknown physical damage were in fact manifestations of cankers.

So a couple of simple definitions


and target cankers that many of you will be very familar with


Both fungi are able to persist in the tissues of the tree largely beacause of an ability to reinfect new wood tissues whilst the tree is trying to wall off the infection.

Now lets look at some examples of what we see a great deal of up here in our Eucs predominantly.
First two Phellinus sp (suspect robustus) in E platyphylla.




Next two Phellinus sp in E. tereticornis




No the issue arises what is going on inside the stem/limb and how to assess this?

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Eric Frei

You get a fair bit of that up there.

Whilst we get it here, it's not that common .... that tree was a removal right?

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Sean Freeman

The second tree is slated for removal, the first has no significant target so will remain for the time being.

It is a bit surpising that there is significant variation between North and South Queensland regarding these same tree species and the proponderance of cankers in them, esp since I know you have the same fungi down there....but thats one of the pleasures of discussing this topic, what is common for me is not for others however the pathogen host relationship I would argue is common across the world...different pathogens and different hosts to be sure, same biology and pathology.

We rarely drill these trees but when we can reach we do sound the entire stem and compare the echos to sound timber (if there is any) in the same tree, in this way we can visualise the extent of decay, sounds crude but you would very surprised at how accurate you become after sounding enough trees then dissecting them on removal (if that is the option taken).

Remember the most widely accepted formula for extent of acceptable decay in the stem/limb....


No whilst I have reservations about this formula when it comes to deciding on removing very valuable trees with marginal targets, it is the best we have and consistancy in risk assessment is essential,,,if you are going to vary from the accepted norm you'd better have a very sound arguement for doing so.

So what do we see when stems with excessive cankers are dissected?
Apologies as I lost the photos of the standing trees but you can see some of the canker fruiting bodies.....note the volume of lost structural integrity in the radial sections.





With a tree like E platyphylla being very white in the stem cankers in fact, any physical defect really stands out. With darker thicker barked trees it can be a lot harder to spot esp if there are no fruiting bodies or they are very small.

Again it is crucial to have a sound understanding of the biology and pathology of both the tree and the fungus. Only then can you confidently apply VTA methodology to assessing these kinds of problems..always being driven by the target value under the tree of course.

Here's two shots of an infected limb removal over carparking bays from E crebra again havent got the fruiting bodies though there were two beauties, Phellinus sp classic pocket rot features in the decayed tissues.




You can see how much of the internal wood tissues have been consumed (or the lignin at least!) by the fungus.

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Sean Freeman

In this examination of fungal decay lets not forget that the tree, the host is not passive in all this, given a supportive, healthy favourable environment the tree can slow even halt the progression of the pathogen.

As we assess trees with identifiable fungal pathogens we are also looking for as many of the contributary elements as we can find...biotic and abiotic factors that have also to be considered in our assessment.

Given the dramatically altered environment that all our urban trees find themselves when I'm looking at street trees and can't find evidence of past or current cankers or infection courts I tend to think I'm just not looking closely enough.....not all fungal infections are reason to condemn a tree. But equally trees with active fungal infections need to be very carefully assessed with regards what other negative impacts are contributing to increasing their stress and pushing them into strain and beyond.

Remember stress is a condition from which the tree system can recover, albeit with probably a reduction in longevity, whereas strain rather like an overstreched steel spring cannot be effectively reversed (though environmental improvements might make the situation more tenable)

Again we have to rely on our knowledge, experience and understanding of both the pathogen and the host when it comes to fungal decay.

As Arborists is essential that we are able to id the commonly occuring fungal pathogens to our own region, and understand their pathology. I personally found that starting with the saprophitic fungi helped me to begin to understand the relationships, and gradually gain greater understanding of the more complex relationship between fungi that consume living wood tissue.

Even though we often classify tree species as being relatively strong or weak compartmentalisers this useful simplification requires greater sensitivity when being applied to situations envolving high value targets or extremely valuable trees. A tree species like Delonix regia whilst generally seen as weak compartmentaliser can in certain circumstances not only occlude wounds but also wall off decay effectively;



and a tree like Caesalpinea ferrea normally though of as one of the most resiliant and resistant trees to both fungal and insect pests can when placed under enough stress fail;




So our models whilst extremely useful to developing general understanding have clear limitations that we always need to be aware of.





So whilst it would in one sense be great if all we had to do was fit our tree species into a table describing health and vigour when grown in our region, and relative strengths in compartmentalisation, combine that with another table for the pest or pathogen and get a result.....the reality is nothing like that.

What we must do is ensure the methods we use to assess each tree follow a clear systematic (repeatable) pattern covering all aspects of the the biology of the tree, and the environment in which it is growing. This is the great strength of many of the better tree assessment methodologies, and must form the foundation on which we build our own specific regional knowledge, experisnce and understanding.

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Sean Freeman

So lets look more closely at how we assess fungal decay by sounding the stem and how accurate we are.

This example is from today, because it came up and Stephen was prepared to play along with my whim.... E platyphylla with numerous fruiting bodies of Phellinus sp as a stem canker.
Its the lower limb at 45'over the footpath;



Now we would have taken this off anyway I'm pretty sure but we sounded the stem near the main union and drew a map of the decay we detected audibly. The circumference sounded is marked on the tree stem.




and here's the map we produced;



here's what the stem actually looked like when Tim cut through it at that point;



So I'm hoping you can all see that a very simple and cheap tool....a nylon hammer can be one of your most useful tools in assessing fungal decay...that map is not bad, and each time we do the audible mapping the better we get at it....we would never rely soley on this technique in situations of extremely high target value, but it would still be a major element of our process.

Trees with very thick and soft bark pose different challenges and with those species drilling may have to be resorted to.

One of the best side benefits of sounding trees that you are going to fell is that you gradually develop a very good understanding of just how the particular fungus develops in that particular tree (in those specific conditions!), and from that you begin to see how trees attempt to manage the loss of structural integrity caused by decay fungi, and of course how this adaptation manifests itself in the body language we can see.

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stirmantrees

As i have been lurking back in the plethora of info here i had a good read through this one.
absolutely captivating. lots of questions. like what is the protocol for getting the soil back in and around the roots?

this thread needs to be discussed more.

Sean Freeman

Not really certain what you mean here, why has the soil been removed?

-To enable Root Crown inspection or similar
-For construction purposes
-Through erosion

As wass raised in another thread conneccted with New Farm Park, massive excavations 360 degrees is a really bad idea, so in terms of what I would want to remove to examine a suspect main buttress you would not be talking about all that much soil, replacing it should be fairly straight forward.

If I have missed the point and you were referring to something far more dramatic then i would need to understand why the soil removal was needed/required.

stirmantrees

referring to a suspect buttress. let say you found no problems. just shovel it back on? water it in i imagine. i assume that inspections must/could remove more dirt than would be good for a tree to leave in that state and i know the interface is important with root/dirt/etc, so i have to think you just water it back in.
But then again looking at the pictures it seems you have just exposed the buttress roots a little. you can learn alot from a little dirt moved.

i am going to take a takedown and have at it. just blow all the dirt away and make observations of decay/etc but i am not familiar with technique(just intrigued as it seems important).

never done it so just treat me as such. lots of overlaping questions i guess.

i know a Quercus Laurifolia that i told them absolutely needs to go, and i have some huge suspicions about what is down below, 4 to 5 foot diameter, already lost 24" + main leader (1/5th the canopy) do to rot and failure, a couple of mushrooms extending out near the base, looks like landscaping changed grade in the past and the buttress roots are nowhere to be seen, decline is beginning to manifest in the form reduced foliage and loss of vigor/some dead, gets tinkled on by the sprinklers 2 times a week, etc.
i am not going to go and just perform a service that i am not familiar with
but if this could be the beginning of learning the process, sooner is better than later.
good ethical practices will make for more profitable work.

Sean Freeman

Ok, in terms of back filling a root crown/buttress root examination then I would replace the soil....you would need to ask yourself if the soil being returned needed treatment ie if there were fungal spores present, if it lacked some basic elements, chemical physical or biological.

Examinations do not really need to massive excavations, we should let the range of data from our VTA drive our next steps, what is the rest of the tree's body language telling us, decay hollows/depressions; signs of lost vigour in portions of the stem/scaffold limbs; reductions in internode distances; patterns of branch breakouts; declining foliage vigour, excessive flowering/fruiting; what are the other trees like in the area; what is the drainage and soil levels like, changed or stable etc....

These days I am much less willing to jump into fungi id than I was when this thread began, I recognise my limitations as an amature mycologist.

It is critical if you believe that a specific fungal pathogen is having a major structural/functional impact on the tree that you get an accurate id.

Different fungi behave in different ways, the state of the host tree is paramount in both understanding the current status and prescribing any future works.

In my opinion we should whenever we have the opportunity inoculate the sol and roots with antagonistic fungi such as Trichoderma sp, trees need such fungi to proliferate in the mulch and organic soil layers to maintain optimum health.

Such treatments cold and I think should be applied when undertaking root exams on trees that are being retained, and on soils adjacent to dying trees being removed that have large wood decay fungi populations.

The two Eucs with the pronounced stem canker fruiting bodies are still standing, intact.

I really hope that over time Arboriculture will end up concentrating on the relationships between tree and soil biota.

stirmantrees

Could you elaborate on the formula that is excepted by arborist for determining when a hollow is completely unsafe. 1/3 diameter of tree left in the form of the outer shell? basically 66% hollow?
i do understand that a Quercus Laurifolia or euc, etc may be different than say a Elm tree or ash, or situations with targets as they determine a critical aspect of this formula. But with insistant customers that do not want to remove a clearly hazardous tree with decay beyond this point it would be good to inform them in writing of what is widely excepted. Or when determing when is the right time to remove a Lead for example. Or when there is like a tiny, well compartmentalized hollow on a tree and the homowner is paranoid the sky is falling.

Eric Frei

Search to forum for "Erk Brudi" or "how hollow" or "pull tests" or "Mattheck" etc as there's tons of information posted about this.

There's no one size fits all however read the PDF's you find, you can have a tree 3/4 hollow but what if it's top has already been lost and it's only a half a tree? There's many variables to consider. Look through the "wall4" thread too.

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Sean Freeman

I understand what you are asking but I have to make a couple of points before trying to answer...

-The use the term safe in relation to tree risk assessment is not something I am at all comfortable with, it is not a term I use, when tree owners ask if their tree is safe, my answer is always the same....No it is not...your tree will eventually fail.

-Hollowness of any part of tree, stem, limb or branch does not by itself tell you anything about the likelihood of the failure of that tree/part under loading.

I recently got into a thread of posts elsewhere along similar lines in relation to tree size and perspectives on risk.

The t/R ratio you quoted is from Mattheck and Breloer (1995) the outcome of their published research has been adopted by a great many consutling Arborists who would state that the required thickness of the residual wall of a stem crosssection shold not be below 0.3 to prevent shell buckling, cross secinal flattening and hose pipe-kinking.

It should be said that I very much doubt that either author (Mattheck or Breloer) ever intended that stem hollowness should be applied in isolation from the other myriad elements of VTA in reaching an opinion by the assessor.

In any case very soon after their work was published questions were raised about the data sets they used and the way the data was presented. In 1998 Wessolly and Erb published data that showed effectively the opposite...where often much thinner reisdual walls are found to be capable of supporting the tree structure under loading.

The arguements about the relative empirical integrity of different approaches are out there if you have the time and the interest to read them.

For me what Wessolly and Erb did was to highlight what many would have found themselves over time assessing many hundreds of trees and having the passion for trees to be able to observe the forest (urban and 'wild') around them....residual wall thickness is not the determining factor in whether a tree (or part thereof) is likely to fail.

Simplifications on complex relationships can be very very useful, they can help us to explain matters to non-Arborists, but they also run the risk of leading us to very poorly supported conclusions in our assessments if we fail to recognise the degree of generalisation within them.

I do not use the t/R 0.3 as a 'line in the sand' and would advise others not to do so...it can however be a simple to remember figure that stimulates greater attention during your assessments. Paying attention to the volume of healthy functional tissue is very important and should be part of the foundation of any VTA.

Some basic questions (not a comprehensive list by any means) to be asking yourself when carrying out VTA...along with many others of more significance (LIKE TARGET?)

-What is the general health of the tree
-What is the form (architecture) of the tree
-What is the history of the tree...expressed by its VTA characteristics
-Where is the tree located
-What is the soil environment like
-What is the wind environment like...expressed in the canopy characteristics of this tree and others
-Is the hollowing typical for the tree given its species/age/environmental history?
-Has the tree responded to the developing hollow in the subsequent growing seasons?

The relative strengths (material properties) of live timber in trees in different locations across the world is something of an unknown, there is some reliable data for Northern Europe tree species, and a small amount of data on tropical trees.

stirmantrees

thank you guys. excellent feedback.

Eric, begun to have allok through some of those threads, some of the pdf's can definitely get heavy. brain doesnt get stronger by watching cartoons

Sean, thank you for your careful remarks. I shall digest and respond.

newguy18

Being someone who specializes in climbing and removing really dead and rotten trees in my opinion if its in a high target area if the decay is more than 25-30% of the trunk diameter or even less in alot of cases its time for the tree to go ,root rot,no more than 15-20%,unless severe excavations have occured near the tree in question,just how i figure and assess trees.

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Eric Frei

There's a lot of really big old oaks your way NG, some large failures have occurred as the trees are over mature and declining, long heavy branches bust off.

Around here the one tree that is highly prized for habitat yet bit of a worry around the house is large old scribbly gums (eucalyptus racemosa). They hollow out nicely and shed which is all good in the bush but close to a target not so good.

On development sites these trees are picked up early by ecologists and efforts made to design around them so sufficient room is provided, consideration is also provided as to traffic under them because positioning one in a park is OK but not above the kids playground. It can be a challenge because of the space they require, which is drip line + some if they shed a honking limb. Now a reader might think, well prune it. Often to prune for reduction there's few targets as the tree is a little self lions tailed, also the large mature to over mature specimens are already deficient in foliage mass so you'll trigger an even faster demise, it's bit of a balancing act so placement is critical as to where the tree ends up .... but certainly not in a domestic house's back yard.

I mean some are like 1.5m DBH, 20m tall and 30m spread, huge dia limbs usually already drooping.

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