UKTC Archive

RE: Ganoderma applanatum/australe on n.maple - implications

Subject: RE: Ganoderma applanatum/australe on n.maple - implications
From: David Lonsdale
Date: Dec 24 2011 11:15:23
Dear Gerrit,

My understanding is that decay fungi extract nutrients only from dead cells 
when they are causing active decay.   Either the cells are already dead 
(because of aging or damage), or they are die as a result of colonisation by 
the decay fungus.  In some cases, the fungus preferentially colonises living 
xylem rays (

Although (as far as I know) there is no evidence of biotrophy during active 
decay, there are certain decay fungi that can colonise living sapwood and 
bark as endophytes, which means that they are biotrophic at this stage of 
their development.  Later, when the colonised tissues are altered by aging or 
damage, these fungi become activated and then cause decay as necrotrophs 
and/or saprotrophs.  These fungi (including various Xylariaceae) can 
therefore be categorised as hemibiotrophic.

With regard to the breaching of reaction zones by Ganoderma 
australe/adpsersum, I am of course aware of the need for caution when we look 
at the results of studies based on the inoculation of sterilised wood blocks. 
  In living trees, I think in principle that good vitality helps to prevent 
G. australe from breaching reaction zones.  I have observed that this fungus 
becomes more invasive if the tree is damaged by excessive pruning or by storm 
damage, but this is probably the result of increased aeration of the wood.  I 
do not have any rigorous evidence to show whether G. australe can breach 
reaction zones even in a host of good vitality.   On the other hand, there is 
observational evidence that it can breach reaction zones more readily than 
various other decay fungi, probably including G. applanatum.

The phenomena of "dying with the tree" and "panic fruiting" could, I think, 
be explained in various ways, and so there seems to be an need for detailed 
research.

Regards,
David


-----Original Message-----
From: Viper Snake [mailto:snake24@xxxxx.nl]
Sent: 23 December 2011 15:45
To: UK Tree Care
Subject: RE: Ganoderma applanatum/australe on n.maple - implications



 
David,
 

1) In your definition does this kind of fungus kill the living cells in the 
process of extracting it nutrients, like a necrotroph, or do they remain 
alive, like a biotroph?, or both, like a hemibiotroph?
1) Because trees affected by G. australe (normally) don't show symptoms of 
(bark or branch) necrosis or dieback (of parts) of the crown or foliage, like 
a biotroph.

2) Are you saying you have evidence that G. adspersum/australe can readily 
breach the reaction zone and/or boundary zone of functional xylem and then 
colonise that wood in a tree with good vitality?
2) Not evidence on a microscopical level in a living tree (yet), but assuming 
G. australe can, because of its (partially sterile) panic fruiting just 
before or shortly after the tree dies and not being able to produce 
(completely) fertile brackets from dead wood alone.
 
Cheers,
Gerrit                                    


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