Fungus on oak

[popewiz]

I have a fungus issue with a Q. nigra (yes, I'm in the southeastern US, hopefully you guys can still help) that has outgrown its planting site. It was planted on the upper part of a terrace within a few feet of the concrete retaining walls on 2 sides. Over time (~50 years) the roots have basically enveloped the top, and to some degree the front, of the retaining wall. On the parts of the tree that are over the retaining wall there are a number of inonotus dryadeus fruiting bodies which I have seen now for the second year (I've only live in house since last Nov.) There is no evidence of the fungus on the tree anywhere where it doesn't contact the retaining wall.

 

I'm wondering if it's possible that the fungus is only feeding on the damaged wood around the retaining wall, or if it is likely a more systemic issue. Any ideas on how I should proceed?

 

Also, I'll try to take some pictures tonight to post.

[Peter]

The inonotus will probably have gained entry via damaged parts of the tree, but once its in it will spread inside the tree.

 

Inonotus causes a fairly slow rate of decay/death, and it affects the roots and lower part of the stem, so thats where you should be looking.

 

Look at the general health of the tree, ie vigour, leaf size, deadwood in crown.

 

Would it cause damage if it were to fail?

[popewiz]

As far as the health of the tree, the foliage is a little sparse, but I'm unsure if that is due to the fungus or the historical drought we've only just recovered from. The leaves are a good size (similar to all the other water oaks), and the tree is producing fruit. There are some branches that fall from time to time (mostly small, < 2" dia.) and I did have a few dead branches pruned out in late winter/early spring this year.

 

As far as potential damage (targets?) the crown overhangs 2 houses, two paths, powerlines, the sidewalk, and the street, so I would say it would almost certainly cause damage if it were to fall.

[Giles Hill]

You've identified that the tree is infected with a parasitic wood decay fungi that might make the tree unsafe. The next step is to carry out further investigation to assess the extent of the decay; this will inform what action should be taken.

 

Typically it would be advisable to measure the thickness and extent of remaining sound wood - i.e. wood that has not become rotten / dysfunctional - in the area where the decay is most extensive.

 

If you are not an arboriculturist, it may be necessary to engage a suitably qualified, equipped and experienced arboricultural consultant to carry out the measurements - they will also advise on whether or not the decay presents an immediate danger, whether surgery work should be carried out to reduce the risk and also when the tree should be re-inspected.

[popewiz]

Thank your for all of your help.

 

As for evaluating the decay, what would be the standard protocol? The company I used to prune the tree earlier this year offers services using a resistograph, is this an appropriate method of determining the extent of decay?

[Peter]

There are various ways of evaluating the extent of the decay, try to avoid drilling holes in it if possible though.

 

Picus is probably one of the better ways, but ideally talk to an independant consultant. Any tree firm can send out a clown with a drill to tell you your tree needs removing, but someone impartial with the right equipment, qualifications, and experience will give you the best result.

 

Of course, it all depends on how attached you are to the tree, you could spend a lot of time and money on it, and the outcome will be the same eventually, the tree will have to be removed. Decay detection and consultancy will extend the length of time that you can keep it, but you cant do anything to halt the decline.

[Giles Hill]

Any tree firm can send out a clown

 

Given our avatars, I don't know if that's meant to be ironic.

 

As Peter mentioned before, Inonotus is less aggresssive than some, so it might be a good number of years before it presents a particular hazzard.

 

Also, looking back, you mention the fruiting bodies are evident on the roots and you asked whether it was only present on the roots, or would it be more systemic...

 

That's a good question as trees are able to compartmentalise decay so that it is contained. How succesfully they are able to do this depends on a number of factors including the vigour of the tree.

 

You might well find there is no significant decay of the main stem and that the consultant will need to investigate the roots rather than the stem. Trees can loose some structural roots, without falling over, but again you'll probably need to take some advice as to whether the remaining sound roots are sufficient.

[popewiz]

Ok, I took a few pictures which may or may not give any further insight. I appreciate all the advice and I am in contact now with a consultant who should be coming around in the next few days.

 

Here is a picture of the fruiting bodies, hopefully I identified them correctly:

 

 

Here area few pictures of how the tree is situated. As you can see it has grown over the concrete quite significantly. There's also a picture of the roots on the side without concrete.

 

 

 

[popewiz]

Lastly, here are a few pictures of the tree's canopy:

 

 

 

[Giles Hill]

Some interesting pics, particularly of the adaptive growth of the roots.

 

I don't know anything about Q. nigra, apart from what I've just read on Wikipedia - Apparently it is a fairly short-lived tree - 60-80 years is mentioned...

 

I'm sure your consultant will have more useful local knowledge on the species.

[popewiz]

The Water Oak (Q. nigra) is a hugely popular street tree where I live (Atlanta, GA) and was planted a lot in older post-WW2 neighborhoods. Unfortunately the first of them are starting to die, and every year we lose a few. There are a lot of recommendations that the replacement trees are Pin Oaks, Live Oaks, or one of several other much longer lived varieties.