Fungi- Ally or enemy?

[Tony Croft aka hamadryad]

Im always looking for new ways and/or examples of tree/fungal (arb-mycota) co evolution to illustrate and confirm my own views, to convince you all that fungi and trees are not at all at war,that in fact they, for the most part are harmoniuos.

 

In the interests of furthering my own knowledge i continue to research the science in both old and new knowledge regarding fungi and the roles they play in forest ecology/pathology. This thread will be the place i post these interesting little snippets as i discover them, the thread inspired by a lovely little snippet today. from Heinz Butin "Tree diseases and disorders" P57-58

 

Beech leaf anthracnose

 

cause: Apiognomonia errabunda (Roberge) Hohn

Anamorph: Discula sp.

 

This disease is characterised by discrete, iregular brown necrosis, distributed in patches on the leaf blade. (Lumina) In years when the fungus is abundant, young shoots up to 30cm lon can be attacked (fig 39) severe, extensive leaf browning can give the impression that there is a serious threat to the tree. The significance of such symptoms should not, however, be overestimated, as experience has shown that even severly attacked trees flush again normaly without any noticable after-effects. On rare occasions, the fungus can also form necrotic spots on the cotyledons of seedlings, these are irregularly circular.

 

Similar necrosis are caused in the spring by the beech leaf miner, but these can be distinguished by the pressence of the mined area which consists of a pale brown patch linked by a narrow tunnel to the midrib of the leaf.

 

In summer, the tiny conidiomata of the fungus form in the dead tissues of the leaves and cortex. These contain large numbers of 1-celled, long-ovoid to ellipsoidal conidia, 9-14 x 4-6 um in size. In the litrature, this conidial state has been assigned to various form-genera [138,218]. These have now been superseded by the rivised taxon: discula umbrinella (berk. & Br.) Sutton [208], although this name should be reserved for a similar fungus that occurs on Oak. In view of the strong host specifity of the beech form, Gloeosporium fagi (desm. & Roberge) Westend. [8] would be more appropriate.

 

From a biological standpoint, it is noteworthy that the fungus occurs in almost all green beech leaves as an endophyte without producing disease symptoms [194]. The fungus only switches to a pathogenic phase if certain gall-forming insects develop on the same part of the leaf. The main species acting as a trigger are the pouch gall midges, Mikiola fagi, and Hartigiola annulipes. the galls themselves die at an early stage of the proscess. it is interesting to regard this as a kind of symbiosis where the fungi is incorporated into the tree's defense system.

 

So, regarding the above highlighted statement, if these relationships are at work at this small scale within the trees biology, just how big a leap forward is it to accept these roles are also involved in root reiterations, stem recycling and limb disposal/abcision etc etc?

[Bundle 2]

I used to paint the flying pigs for Pink Floyd mate....did n't convince me that pigs can fly though!

It is a leap of evidence is all. And I guess funding for research Phd's and such is necessarily connected to usefulness.

For me...the fact we do not know so much and a track record of unwitting blundering is reason enough to court caution in these things...proof though it isnt.

 

Interesting excerpt btw!

[Tony Croft aka hamadryad]

I used to paint the flying pigs for Pink Floyd mate....did n't convince me that pigs can fly though!

It is a leap of evidence is all. And I guess funding for research Phd's and such is necessarily connected to usefulness.

For me...the fact we do not know so much and a track record of unwitting blundering is reason enough to court caution in these things...proof though it isnt.

 

Interesting excerpt btw!

 

Proof no, evidence yes it is:001_tt2:

 

Dictionary my boy! also observe prescision!

 

The evidence is mounting, and shall be "included" within the thread as and when to build the case.

 

I believe now, that there is sufficient evidence to present a valid case to "our" court against the wider theory of pathogenesis/parasitism:thumbup1:

[sean freeman]

Nice post Hama, and yes (IMO) this is just one more good example of behaviour a fungi as an endophyte without pathogenisis until the external conditions (external to the fungi - inside the tissues of the host) change.

 

It is really REALLY important to stimulate both greater appreciation and inquiry of these relationships....all of us tend to fall back on broad generalisations that are easy to repeat to others (tree owners, other arbs, general public) even when we know there is more going on...it is normal to want to simplify things somewhat...but in doing so we need to be cautious that the we don't loose the very essence of the relationship between trees and other organisms (fungi in particular).

 

Thankyou for pointing towards this very specific piece of evidence.

[RobArb]

what roles do fungi play on carbon sequestration within the tree in relation to these reactions? orwould that be another thread entirely?

[bjam1964]

Fungal interactions, in my opinion, with trees are like ripples on the great evolutionary pond.

 

The relationships that are currently pathogenic are currently on the negative part of the wave but still serve an important role. Ie: recyling natures rubbish.

 

The non-existent relationships ie: fungi not involved with trees or moved away from trees are on the positive part of the wave or haven't evolved yet to involve trees.

 

The strictly symbiotic relationships are within the neutral part of the wave but may evolve towards negative or positive.

 

The speed of which this happens depends on the amplitude of the wave.

 

When the evolutionary wave settles down and neutralises, a staus quo is acheived which remains until disturbed by external factors, such as environmental disasters or human interaction.

 

In other words, all fungi have the potential to be beneficial depending on where they are within the evolutionary wave. If we lived for 1 million years we would see the process in action - unless we totally destroy everything through human greed, ignorance and selfishness!

[Tony Croft aka hamadryad]

Fungal interactions, in my opinion, with trees are like ripples on the great evolutionary pond.

 

The relationships that are currently pathogenic are currently on the negative part of the wave but still serve an important role. Ie: recyling natures rubbish.

 

The non-existent relationships ie: fungi not involved with trees or moved away from trees are on the positive part of the wave or haven't evolved yet to involve trees.

 

The strictly symbiotic relationships are within the neutral part of the wave but may evolve towards negative or positive.

 

The speed of which this happens depends on the amplitude of the wave.

 

When the evolutionary wave settles down and neutralises, a staus quo is acheived which remains until disturbed by external factors, such as environmental disasters or human interaction.

 

In other words, all fungi have the potential to be beneficial depending on where they are within the evolutionary wave. If we lived for 1 million years we would see the process in action - unless we totally destroy everything through human greed, ignorance and selfishness!

 

A wave i presume that has an equal and opposite reaction within? i mean to say whilst there is outward movement there is also inward?

 

As THIS science progreses more and more species are eliminated from the pathogen parasite camps, and more to the role of endophytes, symbiots and defense if only as parasites of other parasites!

 

it is said, and i think it an acurate estimate, and probably MUCH lower, that only 1% of fungi are truly pathogens.

 

let us now think about retrenchment, is it lead by fungi or by fluctuations whithin the tree? does an oak stag head because its died back, iether at the root or shoots due to fungal invasion? or do trees naturaly die back and regenerate in times of stress induced by seasonal water avaliability? we see crown symptoms, and i think all to often we investigate decay pathogens, we see decay in the now dead parts, but are they the cause, or merely assisting in the removal and re distribution of resources?

[bjam1964]

A wave i presume that has an equal and opposite reaction within? i mean to say whilst there is outward movement there is also inward??

 

That is deep - but meaningful. If the total premis of life, vis a vis living, is avoiding death and extinction then the evolutionary process must have an equal and opposite process. One or the other would be a step in the right direction to achieve ultimate balance.

 

Sitting above this localised evolutionary fluctuation must be an inbuilt control mechanism that copes with environmental factors ie: drought tolerance, hot/cold tolerance etc.

 

It is said, and i think it an acurate estimate, and probably MUCH lower, that only 1% of fungi are truly pathogens.

 

At the total extreme of the evolutionary wave - a loaded gun of potential waiting to evolve in a more positive way for the host. To continue being truly pathogenic is to truly eat yourself into extinction?

 

Let us now think about retrenchment, is it lead by fungi or by fluctuations whithin the tree? does an oak stag head because its died back, iether at the root or shoots due to fungal invasion? or do trees naturaly die back and regenerate in times of stress induced by seasonal water avaliability? we see crown symptoms, and i think all to often we investigate decay pathogens, we see decay in the now dead parts, but are they the cause, or merely assisting in the removal and re distribution of resources?

 

In-built external environmental factor reaction? A management of resources spread too far/too thin in older age. As self-employed business people we all know about retrenchment in older age and what happens if we don't balance our physical and mental resources

[Tony Croft aka hamadryad]

I think I have found, at last, the propper format!

 

progress!

[Tony Croft aka hamadryad]

what roles do fungi play on carbon sequestration within the tree in relation to these reactions? orwould that be another thread entirely?

 

Wrong terminology, sequestering carbon would require a lack of breakdown, I.e humus is organic residue that has reached profiles where further breakdown is difficult to impossible as aerobic bacteria/organisms cannot thrive there.

 

The lack of humus in agricultural systems is due to constant turn over of the soil profiles exposing organic residues to air and therefore faster breakdown.

 

sequesturing of carbon is more the realm of forest succsesion and the mosses, whereas fungi are the mechanism by which the carbon cycle perpetuates. The communications interface from dead to living and from living to dead, the mycelial networks of fungi.

 

without fungi, there would be no carbon cycle, life as we know it, would not exist, could not exist.