Pseudosclerotial plates (PSPs) difference between Kretzschmaria and Armilliria

[GEOarb]

Hello all,

 

I have seen black demarcation lines or pseudosclerotic plates in cross sections of trees with K.deusta. I have not yet seen them in cross section for armillaria species apart from rhizomoprhs in decayed wood fibre. Literature states armillaria have PSP's but I am struggling to find a photographic sample.

 

I would like to know if there are noticeable and identifiable differences between these PSPs in a macro scale? I am aware that K.deusta use the barriers to retain a dry moisture regime while armillaria use them to retain moisture.

 

If anybody has any photos of a cross section of armillaria PSP's I would love to see them.

 

Also is it possible that one tree with both Kretzschmaria and Armillaria could exhibit two types of PSP?

 

Appreciate any help

 

Ken

[David Humphries]

Hello Ken, welcome to Arbtalk.

 

Interesting topic and thanks for sharing your PSP images.

Where in the word are you based?

Perhaps you have different species of Armillaria than the UK.

Which literature do you refer to?

 

My understanding is that Kretschmaria deusta is predominantly a basal wood volume soft rot decayer, which extends and radiates slowly across trunks and can be found in multiple seperate colonies, with the often seen PSP's walling off the seperate territories within the wood against moisture and other fungal species. 

The more agressive UK species of Armillaria are actively pathogenic, killing off trees by attacking the outer vascular parts of stressed trees but can also be found in cracks and cavities within the wood volumes where I suspect they colonise in a more saprophytic nature. 

 

When looking at cross sections of trees that we've felled associated with Armillaria species (with no other known wood decay species present) I don't recall that I've seen exactly the same PSP's like the ones often to be found in trunk cross sections of trees colonised by Kretzschmaria.

 

What we do see sometimes are the sheets of thin black Melanine plaques (made of the same substance as the coating of the rhizomorphs) which protect the mycelium of Armillaria sp on the walls of cavities, cracks within the wood volume and behind dead bark. I suspect these are protection barriers against moisture, air temperature and other fungal species and fungivores, but not in the same way that Kretzschmaria lay down their PSP barrier zones which I'd believe are possibly created chemically.

 

The following images are of a dead horse chestnut that had these Melanine sheets/plaques behind bark and in cavities and cracks.

 

 

 

 

 

 

 

 

 

 

 

 

[GEOarb]

Thank you David.

This all stems from a bit of a lack of understanding on my part, I am a Brit now based in NZ and noticed armillaria symptoms on an old Tulip Tree. I also noted that some of the extensive decay cankers had what looked like old black Kretzschmaria fungal crusts. Yet kretzschmaria is not found in NZ but I mentioned it as an outside possibility. Turns out the nearest case is just across the Tasman in Newcastle so its occurrence is not entirely impossible especially as its so difficult to spot. The middle photo shows a cross section from the tree, which I personally think looks just like Kretzschmaria rather than armillaria. As you say the black marks seem to be chemical rather than from rhizomorphs. The lower photo is armillaria novae-zelandiae we believe, you can pull the black rhizomorph off.

I guess it is possible that the NZ honey fungus has the same characteristics as Kretz but I personally think its unlikely as the two photos show.
I have other photos of what I think are ascospores which I will upload. The top photo is from an Acer that also seems to have similar kretz characteristics.

I appreciate your help identifying my photos if possible, I realise that NZ fungi are generally different and will have different strategies, perhaps.

The Tulip tree had vascular issues including noticeable strangling resulting in upper canopy branch failure, smaller leaves etc. It had also lost a few larger limbs in the recent past, just missing the house below. It is a multi stemmed tree from 6m and each scaffold had a large canker up to 6m in height all of which had copious small fungal fruiting bodies below the sloughed bark. Unusually the tree had advantigous roots at 6m into the fork crutch which was full of rotted leaves and now soil. There was no evidence of fungal fruiting bodies in the overly hard landscaped root zone.

I hope this is of interest.

[GEOarb]

Some close ups.