Assessing Fungal Decay

Sean Freeman · 12th July 2007, 11:54 PM

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.

Sean Freeman · 13th July 2007, 12:05 AM

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 · 13th July 2007, 01:03 AM

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!)

Sean Freeman · 13th July 2007, 01:15 AM

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.....

Sean Freeman · 13th July 2007, 01:34 AM

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.

Ekka · 13th July 2007, 03:04 AM

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!

Sean Freeman · 13th July 2007, 04:15 AM

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.

TrevMcRev · 13th July 2007, 04:24 AM

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

Ekka · 13th July 2007, 04:48 AM

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.

Ekka · 13th July 2007, 05:00 AM

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.

Sean Freeman · 13th July 2007, 05:05 AM

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.

Sean Freeman · 13th July 2007, 02:47 PM

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.

Sean Freeman · 13th July 2007, 06:13 PM

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

13th July 2007, 12:05 AM	#2 (permalink)
Sean Freeman PDF King & Arborist Extrodinaire Join Date: Feb 2007 Location: Townsville Nth Queensland & Gold Coast Sth Queensland Posts: 1,643	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 Trees are poems that earth writes upon the sky, We fell them down and turn them into paper, That we may record our emptiness. - Kahlil Gibran

13th July 2007, 04:24 AM	#8 (permalink)
TrevMcRev Over mature heritage tree Join Date: Feb 2007 Location: Melbourne, Victoria, Australia. Posts: 727	Excellent thread start boa. Look forward to what unfolds in here. __________________ Melbourne Arborist, Total Tree Care, Pruning, Tree and Stump Removal