Is My Silky Oak Dead ?

Rick W

My mature, 25m silky oak has lost all its leaves & I'm concerned it's dead. All other oaks in the region (Brisbane, Australia) are in leaf. We had a new fence put up a few months back but didn't cut any roots. There have been no major branches breaking off. No bark appears to be falling off either. Any thoughts or further questions ? Please let me know.

I attach 3 jpeg photos for your purposes.
Many thanks, Rick

Attached Thumbnails

     

Eric Frei

Well, this is an interesting mystery.

Did the leaves all fall off at the same time?

Were they crisp and brown or were they slightly yellow/black and perhaps a little soggy?

Around the tree, is it a wet spot?

I wonder what the soil pH is?

The upper canopy doesn't look dead yet, the tips appear supple, might be shocked for some reason.

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Rick W

Hi Eric - thanks for your help.

The leaves have fallen over the past 2 months. They were crispy and brown.
It's not a wet spot around the tree.
I have not tested the ph of the soil -should I do this ?

Eric Frei

Well, does other vegetation nearby look sickly or yellow? Doesn't to me so it's probably OK.

How close are any storm water or sewer pipes?

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Rick W

There are several alexandra palms and a large hibiscus nearby but all are in good GREEN health.

Stormwater & sewerage pipes are nowhere nearby ...

How long should I wait before I panic ? I fear the thing may fall on me or my neighbours !

Eric Frei

You have around a year up your sleeve. The wood looks OK, there's evidence of recent growth and wound wood so it's alive.

Who would benefit from the demise of this tree?

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Rick W

No one save the fellows employed to cut it down. I want to keep it so will just keep hoping it fights back and comes into leaf.

Eric Frei

Tree roots spread easily to the drip line of the tree.

Try treating with this product. They are here in Brisbane and tell them Eric from Treeworld sent you. Apply liberally to the drip line, hose in. Also when you are there it never hurts to apply this one either.

Treat to the drip line, do not fertilise just use those products. Rainwater is better than tap water to use, do it with watering cans you'll need many to get coverage to the drip line, best done just before or during rain.

Keep us posted on progress.

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Garry Brockley

Was the fence concreted in? it looks to be between two major root systems if the roots were damaged whilst digging the hole, which i would say they would have been as there is no working room there, then concrete poured on them the lime will leach straight in to the tree roots, I have installed thousands of fences and an area like that cant help getting damaged whilst digging. personally thats what i would say was your cause of the trees demise.

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Rick W

I fear you may be right ... Are there any measures you can suggest to remedy the leaching into the roots or is it a case of wait n see ?

Eric Frei

Well spotted, I missed it, but was thinking along the lines of root damage from pipes etc. You think they'd have spaced the fence better instead of putting a post right on the buttress.

Rick W, you need to do a root crown investigation to see what damage has occurred to the tree root, it's very close to the tree and could even destabilise the tree.

Have a look through this thread and you'll get the idea of what to do. Do not pull bark off or damage tissue, gently Bently, use a hose with a little pressure and a hand trowel.

Post pics of what you find.

Unhealthy melaleuca leucadendra (broad leaf paperbark)

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derwoodii

Monsoonal Deciduous Trees its not lookin this way but perhaps your trees just got its calender mixed up.

Down here Silkys often loose leaves as part of their natural cycles to which I am still a bit confused with. Last year in high drought before summer rain many were almost totally leafless. Perhaps your is just doin its thing.
The blokes in QLD will be in tuned with the hot wet growth seasons up there.

Some Australian trees can be partly deciduous in that they may lose foliage on a half or more of the tree just prior to flowering while retaining it on the other half. The Illawarra flame tree (Brachychiton acerifolius) is the best known example of this and it can sometimes be observed on the silky oak (Grevillea robusta).All these trees actually come into flower as the rain comes, to give their seeds the best possible chance of germinating.