Fungal Findings

treesandsurf

Was called to look at this Oak (Quercus spp.). There was some larger deadwood in the canopy, and apparently the tree looked 'sicked' when it was leafed out. Found the following after scratching away several inches of soil (debris) that was mounded over the root collar. Any ideas?

First guess is A. mellea but the coloration (very white) of the fruiting body and the fact that only found one in an isolated area threw me for a bit of a loop. There was presence of 'shoestring' like mycelium on surface of bark and soil.

Will be returning for a more comprehensive root crown inspection soon.

jp

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treevet

A. mellea.....shoestrings (rhizomorphs) yes

no honey colored caps then ..no

Do they have a ring around the central stem?

Are you sure the mushrooms are related to the decline? Are they on the same side?

Sean Freeman

very hard to make out any ID based on the pics but I agree with Treevet, certainly does not look like the fruiting body of A. mellea .

There are other fungi that produce shoestrings (rhizomorphs) given the right conditions in the organic layer of the soil....none of this is to say that A. mellea might not be present of course.

treesandsurf

My apologies, the pics aren't too great.

I found evidence of the mycelium in more than one location, but the fruiting body there was only that one I pictured (from what I've excavated thus far).

I'm a bit confused by your question as to the relationship between the location of the fruiting body and the area of the decline in the tree? I suspect there will be more decay found once the root crown has been inspected.

jp

treesandsurf

Possibly a different species of Armillaria? I'll take better pictures for the RC inspection.

jp

Sean Freeman

No that wasn't what I meant rather I was alluding to the production of plentiful hair like rhizomorphs by a number of Mycena spp thought that is not what the fruiting body you showed looks like either.

Did your observations lead you to think the rhizomorphs you saw were physically connected to the fruiting body in the pic? Or was it too hard to say with any confidence.

treevet

Fruiting body, rhizomorphs on same side as predominance of deadwood/decline.

Have we considered other reasons for decline or opportunity for fungal attack.

treevet

Like you said Sean, the existence of A. mellea is not ruled out for lack of fruiting body. Rhizomorphs are not found associated with many fungi. Also "mushrooms are not frequently seen", but there are many other similar fungi that also fruit at the base of trees that are mistaken as Armillaria. They likely are 2 different entities.

Tree Machine

Armillaria, spp most often fruit in clusters. Rarely will you find one, they come up by the dozens in patches, not usually off the tree but out of the root flare or roots just below ground. This gives the impression that they're growing out of the ground near the tree, but they're actually growing off the tree under the ground.

treevet

yes, and you can find them all over the lawn and the tree doesn't need to be there anymore nor does the stump.

Tree Machine

Armillaria is one of the more well-known fungi in the Arbo word, but it is not one of the most common. Armillaria is different than most fungi, in that it will attack a living tree. This is REALLY unusual in the fungal world. This classifies it as a parasite, one that makes its living off a live host, where the host gets nothing in return.

Most all wood decay fungi are saprophytes, that is, they've evolved to live off dead matter and decay it back to soil (humus). For saprophytes, their opportunity comes when a tree or part of a tree dies, they take hold. It's a specialized and necessary job.

If fungi attacked living trees, just by the sheer ability to spread their kind by the wind (via spores), they would win and eat all the trees and then have no food source. By NOT attacking live trees, the trees provide a continuous and sustainable food source for the world of fungi, and in return the fungi break down the dead parts to become part of the soil which in turn enriches the soil so the trees can thrive. Symbiosis.

Armillaria is a rogue that doesn't play by the rules.

Sean Freeman

Hi Jim, don't loose sight of the latest microscopy work that is helping us to understand just how fluid the relationship between fungi and tree host is.

Schwarze's latest work "Diagnosis and prognosis of the Devevlopment of Wood Decay in Urban Trees" provides us with a far more detailed look at both the cellular construction of wood tissues and the various means of cellular decomposition available to different fungi.

Understanding that there is an observable co-evolutionary pattern of adaptation in decay fungi to the wood substrate can help us to explain the different modes and methods of wood decay (brown rot/white rot-simultaneous rot and selective delignification) exhibited by individual species of fungi.


Armillaria is interesting since it has been studied since 1878! It was one of the main fungi on which Robert Hartig based his fromative work.

Within the various Armillaria spp the degredation patterns observed are those of a white rot with evidence in the cell wall structure of both soft rot, simultaneous rot and selective delignification.

It is hardly suprising then that Armillaria is successful in being able to colonise and advance through wood tissues, however just how successful any fungi is within any specific tree is dependant on a whole range of factors relating to both the actual physical cell architecture (reflecting the evolutionary path that tree species has travelled) and the intercellular environment (reflecting the health and vigour-factors both of the internal and external environment to the tree)

So for me (dependant on all these interrelated factors) a specific fungi might at certain times be described as behaving in a manner similar to a saprophitic and at other times in ways that fit into a more parasitic model....however the terms might be less helpful in understanding and describing what is actually happening between the fungi and it host.

treevet

I think A. mellea vascillates between saprophyte and parasite in its strategy to delignify wood. Ultimately it becomes the saprophyte but can change strategy when necessary to advance or if other live trees are colonized through entry of concurrent roots or spore transmission. I do not see this as evil or good or a rogue.

It is life just as the shark eats the baby seal. It all ends up in a symbiosis if it occurs in the woods for the benefit of the forest. If in an individual setting then the symbiosis is not existent (where is the mutual benefit?) and more so this likely what caused the availability of attack more readily in the first place. As far as it being a primary pathogen it probably can be or it can follow successive attacks of other pathogens. Compartmentalization is the limiting factor obviously. This ability is based on many factors.

It is interesting to me how it will use the availability of water to advance, then when it is depleted, it waits/stalls, and then the remaining substrate is more accepting of water to renew and increase the attack.

treesandsurf

So when the shark eats the seal it's a saprophyte but when the shark eats a human....parasite!

Nice discussion... will be taking a closer look with the camera and possibly take it down to the lab to confirm ID in a few weeks.

jp

treevet

I think if the shark eats a dead seal he is a saprophyte, If he eats the human a little at a time and lets him recover somewhat he is a parasite. (?)

Look forward to following your story.

Tree Machine

In the plant world we call that a saprophyte. In the animal world we call it a scavenger.

treevet

You are getting a little technical here. A casual analogy was made. Ability to State the obvious is not a gift.

Saprophyte..."An organism, especially fungus or bacterium that grows and derives its nourishment from dead or decaying matter".

Technically an accurate description anyway as you can see.

Sean Freeman

The important thing to remember (if you want to remember anything!) is that the fluctuating relationship between the tree and the fungi is very important it will inform you as to how best to approach treatment for the tree (if it is to remain).

The discussion about mode of action is relevant, understanding just how a specific fungi comes to occupy a site in the tree, in the wood tissues, and how that fungi will attempt to digest the lignin within the cell walls is critical to our diagnosis and recommendations.

It is impossible to imagine a scenario where the fungi we get to observe in the wood tissues of a tree (when the owner or someone else decides there is something wrong) is the fungi that first breached the tree defences.

It is very important to be able to descern what species your fungi is, since that has a massive bearing on how seriously it may be able to compromise the structural integrity of the tree....that and OF COURSE the state of health of the tree

What I'm getting at is the saprophite/parasite debate is less important (though very interesting) than the accurate fungal ID and the understanding of how a specific fungi and the specific tree species relate.

(I am making the a priori assumption that the target makes this more than just academic musing)

The pathogen-host relationship between most of the Armillaria spp and many tree species has been well researched and documented.