UKTC Archive

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

Subject: RE: Ganoderma applanatum/australe on n.maple - implications
From: antony croft
Date: Dec 21 2011 19:41:40

which fits with the fact that true pathogens are an extremely rare breed.
although in the U.K Pfiefferi is far from rare.
tony

From: snake24@xxxxx.nl
To: uktc@xxxxxx.tree-care.info
Subject: RE: Ganoderma applanatum/australe on n.maple - implications
Date: Wed, 21 Dec 2011 20:33:29 +0100


 
Dear David,
 
Although there is quite a difference in your definition of biotrophic and 
necrotrophic parasites and the definition of both terms on the continent, 
as is included in all Dutch, German and Scandinavian literature I refer to, 
I consider your definition to be the more precise.
 
And after always microscopically assessing what perennial species of 
Ganoderma I found on beech in The Netherlands and Germany, I have come to 
the conclusion, that about 95 % of perennial Ganoderma species on beech is 
G. lipsiense, followed by the rare G. pfeifferi and the extremely rare G. 
australe.
 
Regards,
Gerrit

 

From: d.lonsdale2@xxxxxxxxxxx.com
To: uktc@xxxxxx.tree-care.info
Subject: RE: Ganoderma applanatum/australe on n.maple - implications
Date: Wed, 21 Dec 2011 18:29:51 +0000

Dear Gerrit,

In answer to your question, I define the relevant terms as follows:

1. Biotrophic parasite: a parasite which obtains its nutrients from the 
living cells of the host (usually by the penetration of those cells, 
without killing them). Examples include rusts and mildews.

2. Necrotrophic parasite: a parasite which obtains its nutrients by 
killing cells of the host (usually by the secretion of enzymes and/or 
toxins). These parasites are usually able to grow also as saprotrophs (4, 
below) and they are therefore often alternatively called "facultative 
parasites". Examples include many fungi and bacteria that cause general 
dieback and/or decay of host tissue.

3. Hemibiotrophic parasite: a parasite which obtains its nutrients both 
as a biotroph (usually when it first penetrates host tissue) and as a 
nectroph (usually at a later stage, after an initial biotrophic phase). 
Examples include many organisms that cause leaf spot diseases.

4. Saprotroph: an organism which obtains its nutrients from the dead 
remains of one or more living organisms.

As far as I know, there are no wood decay fungi in categories (1) or (3) 
above. Some of them have the ability to grow into previously living 
sapwood, causing it to die (or become "dysfunctional" and then causing 
decay. I think that they can be regarded as necrotrophic parasites (2), 
but I do not like to use this term without qualification, since many of 
them live predominantly on wood that is already dead. This could be 
sapwood that has been damaged by injury, or it could be central wood or 
the tree, which has become heartwood or ripewood because of aging. 

Traditionally, wood decay fungi have been described as "parasitic" if 
they are found on living stems, branches or roots. I do not think that 
this is correct if the fungus concerned is colonising only wood that is 
already dead.

According to the above definitions, Ganoderma applanatum has been 
observed to be mostly saprotrophic, whereas G. adpsersum/australe has 
some capacity to act as a necrotrophic parasite. These observation seem 
to be confirmed by some experimental work by my friends Schwarze & Ferner 
at the University of Freiburg i. Br., Germany. (see: 
http://www.enspec.com/articles/ENSPEC%20Research%20Paper%20-%20Ganoderma%20on%20Trees.pdf
 )

Schwarze & Ferner found that G. adpsersum/australe was able to penetrate 
defensive barriers (reaction zones), thus growing into functional 
sapwood. It does not necessarily harm the tree seriously. Instead, it 
might be able to co-exist with the tree for many years, instead of dying 
out when it has utilised all the wood that was initially available to it. 
In some cases, however, the fungus does enough damage to the sapwood 
(especially in the roots of the tree) to cause the decline and perhaps 
death of the tree. Also, the decay can, in my experience, become 
overwhelmingly rapid if the wood becomes more aerated because of 
excessive pruning or the storm-breakage of major branches. 

As suggested in the recent correspondence, G. adpsersum/australe appears 
to behave differently in different host species. I think that it can be 
especially aggressive in species with which it has not co-evolved. I have 
seen examples where G. adspsersum/australe (or perhaps a similar-looking 
species of Ganoderma) seems to have killed exotic conifers such as 
Araucaria araucana. I agree that it can cause extensive decay in the 
broadleaved trees in your list. However, in Fagus sylvatica (one of its 
main hosts in the UK), the tree and the fungus often seem to co-exist for 
many years. The co-existence is probably even longer in species like 
Quercus robur and Q. petraea, which have durable heartwood and therefore 
tend to become decayed more slowly.

Regards,
David

-----Original Message-----
From: Viper Snake [mailto:snake24@xxxxx.nl]
Sent: 21 December 2011 14:14
To: UK Tree Care
Subject: RE: Ganoderma applanatum/australe on n.maple - implications




David,

1). Tony Croft has been using the term 'biotrophic parasite' in relation 
to G. adspersum/australe on here. I questioned him about these labels and 
asked him whether he could point me to any research that demonstrated 
that the fungus was 'biotrophic' and/or 'parasitic', because this was 
news to me, but he hasn't replied yet. Can you point me in the right 
direction?

1). Tony uses my terms and the results of my in situ research on 
biotrophic and/or necrotrophic parasites, which I already have explained 
on Arbtalk, see : 2. http://arbtalk.co.uk/forum/529703-post53.html .

2). Similarly, that G. adspersum/australe is deterministically fatal to 
Acers, no matter the circumstances, is also news to me. Where does the 
research for this conclusion come from ? 


2). From my own field research on the effects on the stability and 
condition of different deciduous tree species of the biotrophic parasitic 
G. australe, of which the mycelium causes a white rot with selective 
delignification, that is most detrimental to Acer, Platanus, Populus, 
Salix, Tilia, Aesculus (Anne Frank tree) and Quercus rubra.

Gerrit





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http://www.arborcentre.co.uk/
                                          


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The UKTC is supported by The Arbor Centre
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