Armillaria investigation

[David Humphries]

One of our team picked up on the fruiting of an Armillaria species whilst out inspecting this lime recently.

 

The google image below is the tree from July this year, which appears to show the tree in relatively good vascular health

 

It was reduced in height approximately 6 years ago due to its isolation against the prevaling wind direction.

 

The fruit bodies are consitant with what I would expect of Armillaria mellea as opposed to Armillaria gallica.

 

A. mellea is considered a more aggressive pathogen than the more benign A. gallica species.

[David Humphries]

The immediate locality has a large number of fruiting bodies popping up both inside this park and also at the base of neighbouring street trees (horse chestnut & hornbeam)

 

 

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[David Humphries]

today we took the opportunity to have a closer look & investigate the situation regarding the lime specifically.

 

We airspaded out a couple of areas where there had been fruitbodies at the base of the tree, and were not surprised to find a significant number of rhizomorph bootlaces in amongst the roots of the lime.

 

in the first opened pit we discovered a heavily degraded (white rotted) smaller root but the buttresses and major roots appeared sound after a tap with a sounding hammer

 

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[David Humphries]

in the second pit we soon came upon a subteranian girdling root across one of the main roots.

 

The airspade stripped the bark off this girdler and on inspection it was discovered to be dysfunctional & heavily decayed.

 

Again, the adjacent roots & butresses appeared pretty sound and functional.

 

 

 

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[David Humphries]

....... and were not surprised to find a significant number of rhizomorph bootlaces in amongst the roots of the lime.

 

the soil was saturated around the root zone and made identifying the rhizomorphs from root a little difficult but a wash and seperation soon helps

 

 

all the material in the last image are rhizomorphs

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[Paul Melarange]

Very interesting, thanks for sharing David. Hopefully the disturbance of the soil in the root zone will limit the honey fungus. It will be interesting to see if it reappears next year.

[David Humphries]

Hello Paul,

 

Thanks for your comment.

 

As you know, there is documentation from Glynn and others that air spading can have a positive effect against Armillaria, but I believe that as this area is inundated with the dead roots of previously removed trees out on the roadside path outside the park, the top soil layer will have a significant volume of active rhizomorphs through out it.

 

We're considering a further reduction of the height of this lime, but that will no doubt have an effect on the creation and distribution of produced energy which could tip the balance of this trees ability to keep healthy and functional against the presence of Armillaria.

 

 

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[treeseer]

No surprise that the girdlers are not resisting decay, as the tree is shedding them. The A. could even be considered a benefit by finishing off the girdlers.

 

For backfill, is there any expanded aggregate available? Attached ppt was the best talk at ISA-europe this past May. Amazing adventitious root growth off the buttress, into a well-aerated environment. Slides ~50-60?

 

Thanks as always for showing your fine work managing trees and fungi!

 

Please pardon me to doubt this popular assumption: "a further reduction of the height of this lime, but that will **no doubt** have an effect on the creation and distribution of produced energy which *could* tip the balance of this trees ability to keep healthy and functional against the presence of Armillaria."

 

. As noted by Peter del Tredici of Harvard

University (Cambridge, MA), “Pruning rejuvenates by inducing the growth

of younger meristems, shortening the internal transport path, and

balancing shoot load and activity with limited root activity and

support. In trees, physiological and developmental aging operate

independently. They can be simultaneously embryonic and senile,

resulting in a form of ecological immortality. It is this potential for

immortality that makes trees so fascinating to work with.”

Luigi pdf root regen english.pdf

Edited November 25, 2014 by treeseer

[daltontrees]

Great thread.

 

I'm in the 'no doubt' camp. Pruning rejuvenates but that's all very well on a healthy tree. But the net removal of a large amount of ripe buds will set the tree back considerably. In spring when it flushes it may not have enough transpiration suction for proper vascular function, and needs to expend its reserves on redressing the root/shoot balance, or roots will die. It may bounce back but at quite a cost. Meantime the fungus marches on. There is room for an argument that the removal of canopy removes the energy sourve of a pathogen and slows its development. But if the pathogen is feeding on cellulose and/or lignin, it won't be slowed at all. Net gain for pathogen. Could tip the balance. Worth a go in a 'nothing to lose' scenario.

 

David, to what extent do you consider whether the early removal (stump and all) of Armillaria victims as food sources for further spreading to adjacent stock? This is not a loaded question and I don't think there is a right answer, I am just curious about your perspective on what is for me an age-old dilemma.

[David Humphries]

Interesting presentation Guy, thanks for sharing. I often find these types of Power Points hard to stay focussed through-out so appreciate the chance to see them afterwards. Helps if you get the odd banana thrown at you by the presenter.

A little difficult to follow in parts without the benefit of the talk to go with it.

But I think we got the gist. How long was it.

 

Have you had experience of return visits to trees that have been subject to Armillaria then had soil amelioration undertaken?

 

 

 

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