Pohutukawa| Metrosideros excelsa, thomasii, kermadecensi| Lifespan| NZ Christmas Bush

Eric Frei

I'm in Brisbane Australia and found these don't live that long.

In my experience they have little tolerance to drought, have an unusual root system where even aerial roots hang and there's some bizaar stump configuration between that of a ficus and a bottle brush.

Anyway, often I find trees with large dead patches/branches etc. Numerous small borer holes (2mm max dia) in the light dead branches which are brittle and decayed. Parts of the tree may be live but overall it looks like crap. They could even have flowers on parts of it.

They seem to have about the same lifespan as many wattles, they seem to be dying around 20 years to maybe 30 years of age.

The death pattern seems fairly much the same from the coastal sandy Gold Coast to the clays of Brisbane.

They can be between a large shrub size say 3m tall and wide to small tree say 6m tall and 4m wide. The one I took out today had a great place to live with plenty of mulch, other trees close by were OK.

So what are your experiences with this tree?

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azrael

Ahh......
I've seen two Metrosideros die at the end of my street over the last 2 years....and alarm bells rang when the second one died some 1.5 years after the first. (Illawarra Region - South Coast N.S.W. Coastal Plain with Av. Annual Rf 1200mm pa).

I must say it was quite a rapid death...one dead branch (insignificant???), then the next thing ....whoof....whole thing dead in less than 1 month. No yellowing, just attached dead foliage...& dead tree.
One dead tree has beenremoved but the second mortality still stands...(I shall investigate the borer scenario.....& keep you posted.).

The area where I live is abt. 25yo as far as subdivisions go. Our area was stripped of topsoil at subdivision, and we have heavy clays, so its mulch..mulch ...mulch....mulch if you want to grow anything....very challenging soils....raped through agriculture and grazing, then stripped to sub-soil at subdivision...(criminal really).

Both specimens were front yard plantings...(in turf)...and not recieving any supplementary watering since water restrictions were imposed here.

(As distinct from paperbark Melaleucas, it seems the aerial roots in Metrosideros dont seem to help longeivity if there is no rainfall).

Otherwise I've seen specimens many which have reached enormous trunk size, and been quite healthy (mature trees)....but these have been in moister, more protected locations with better loamy soils. Also have seen same (mature specs) in hindune areas performing relatively well (relative in that they were very wind formed, and had disfiguring branch losses).

Mmmmm.....Im interested to hear other cases too.

Quintrex

In Sydney they seem to thrive in the sandy coastal soils around Cronulla and Maroubra and similar areas. A big one here would be 6 m tall and spread about the same with a DBH of a metre or so. They were extensively planted as street trees by Randwick council maybe 30 years ago or so. I don't know how long they generally live here, but older specimens tend to die back and decline and become affeced by small longicorn larvae as you described in Bris.
Arborcraft should be able shed more light on this, they are prolific in his patch.

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Heightmaster

TrevMcRev

They generally do pretty well here in Melbourne further south.

I guess most of NZ is cooler still, so Qld probably not ideal.

Any Kiwis got any input?

Hili, what were they like when you were over there?

Ive seen similar "shutdown" behaviour in many Hakeas here lately...

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Eric Frei

Exactly what happens here, the dead brown foliage still attached ... sorry for not mentioning.

The borers are post death though and infect the dead branches only not the live, they're just being adventitious.

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Done it

They grow well around here, saw one today in flower but well protected by the tree I was quoting. I've done a lot of those half dead ones in the last few years. Trev is right they need the right climate, they can survive without water [rain] but not if in direct sun. Once a bit dies off the borers come & that's it. Great firewood, hard as nails when they're dead. NZ at least a week of warm nights last winter.

Eric Frei

Hmmm, they're like balsa wood here when dead, dry and light, nothing like say wattle.

Also, they seems to have lots of bugs on them, this one had lots of stink beetles on it and I tend to get a little itchy from the dead ones. Could be some itchy bugs on them, dont know.

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treekiwi

hey guys, little bit of kiwi output i suppose, pohutukawas are everywhere and get prity large, spread of up to 60 metres or so, mostly coastline. They do have aerial root systems, sometimes reaching to the ground and continuing to grow, huge laterals that touch the ground. The only real problem here is leaf miner which drills the leaves but other than that not really a problem. they are actually a HUGE weed in South Africa and grow everywhere theres a bit of dirt so i shouldnt see a problem in Aussy. Timber is very strong and red in colour heres some photos...

http://www.opotiki.com/data/pictures/tekaha3.jpg

They can live for anywhere up to 500 years and some of the bigger ones have girths of up to5 or 6 metres.

treekiwi

canopy of a very large one, estimated 300yr....

Done it

Good pictures, I don't think you'd find any that size here. Metrosideros means "Heart of iron" referring to the red heartwood. They are sand and salt resistant. The reason they were dying here I think was the lack of humidity during our long dry spell. The timber isn't hard green but when it dries out it is. Not as hard as wattle but close.

Eric Frei

Bugger me! I aint ever seen them that big, now the 60 metres must be a typo though.

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TrevMcRev

Theres a big one in the Botanic Gardens in Melbourne

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Eric Frei

Some pics

The typical borer hole.



Where the borer ate the cambium layer



Some weird cocoons on it.



And all cocoons opened the guy inside was dead.



Cannot say the borers had anything to do with the cocoon though. The decline seems more severe on the variegated ones.

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shaun05

The borer is form the order Coleoptera and the family Curculionidae.

The cocoons were made by a Lepidoptera thus eliminating them from being the cause of teh exit hole since the xylophagous moths fit generally into Cossids and Xylorictids with both groups pupating internally.

Treeson

Just thought I'd throw these pics up of some 'Pohoots' just down from my old place in Auckland.

The big boy on the beach front is about 6-800 yrs old.

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pcarborist

Looks like bagworms (Psychidae).

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parkcityarborist

arfabuck

Pohutukawa's are a protected specie with most Councils in NZ.

Auckland ARC has fined a fella $5,000 for dropping one last year without consent. Any native over 13' high is protected and needs a permit to be removed,- except Franklin District Council where I live. They do not have a "tree policy" as such, apart from some 33 trees that are listed as "protected".

Does not appear to be an issue here, the only rapists are the sub-division developers - but they have to get Resource Consent to build anyway.

The oldest known Pohutukawa is out at East Cape, will get a pic later.

Treekiwi correct me here if I am mis-informed.

arfa

ahutch

Hi Guys

I am in Perth and have one that is over twenty years old, appears healthy, no problems except it has never flowered. Is this unusual? Please advise

dustbinflowers

Hi Ahutch

is your pohutakawa in a sheltered situation? ie, little salt, wind or other stress?
If so, it may see no reason to reproduce- life is cushy, and flowering takes a lot of energy!!
I have no direct experience, but I have heard of someone dumping a bag of salt on the roots of their non flowering 20 year old plant, resulting in great flowers the next season. To me that sounds like a drastic thing to advise someone to do- maybe just a little bag?

I have seen pohutakawa affected by pesticide flower early, but I definitely wouldn't advise that!

I hope this is helpful

sueann

Amazing pics!

dustbinflowers

In regards to the Pohutakawas suddenly dying: I heard Myrtus rust mentioned as having been found on Australia's east coast recently- maybe it or something like it could be getting the trees? The relatively fast collapse sounds like a blight or other fungal infection.

Just a thought...

jmcg.insight.gardens

As far as I'm aware the Myrtus Rust was an isolated outbreak at a flower farm down the road here, I believe it has been contained.

Metrosideros collina seems to handle the humidity here far better than the others, my observation so far. The variegated forms seem to struggle generally.


Many studies have been done on the flowering of Pohutakawas, it seems that flowering has yet to be fully understood, as to the trigger. They are renowned to be inconsistent.