Arborists’ opinions on poisoned Adamstown trees 15.4.2012

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This is the question I asked five arborists:

The fall-out from Laman Street’s desertification is that all Newcastle’s large trees are in NCC’s firing line.

The trees in the photos – courtesy of a friend on Facebook –  are in a park in Adamstown, about three suburbs from Laman Street; they were allegedly sprayed with round-up four years ago and their bare branches at the tops of the trees are attributed to that assault.

They are slated for removal as a result.

As a know-nothing treehugger, I would have thought that pruning the branches  that have no leaves and looking after the trees, presumably mulching them at the right time, would give them a chance to recover.

I’m reasonably sure NCC has done nothing to care for them since the alleged poisoning.

I know I’m not giving you much to go on, but do you think their death is likely to be inevitable?

Cheers, Caity

http://www.theherald.com.au/news/local/news/environment/more-newcastle-city-trees-to-go/2517278.aspx

I’ve heard back from four experts. All they had to go on were tiny photos so there’s a limit to how much they can determine but here goes:

i)
I understand too well your loss of faith in the council managers to make sound decisions; unfortunately the pictures don’t tell much. Could be the trees will continue to decline, death is inevitable for us all, but the questions would be how long will that take, can it be delayed and at what point will the cost of maintaining the tree outweigh the benefits is confers.

These questions are likely to be something that any good manager would attempt to satisfy before removing a tree but I suspect budget spreadsheets, operational matters, politics and personal preferences play a bigger part.

I’m personally a bit of a deadwood fancier so I would not feel any need to remove the dead limbs or the trees unless they represented an unacceptable risk but I guess most would think that they are unsightly and prefer a more manicured approach to landscape.

I wouldn’t think it unreasonable to expect that council should have a tree replacement policy or planting strategy for the city. Not sure what they have in place in Newcastle? Maybe that is something that the community could have some say in?

Maybe get a local arborist to give these trees a look over if you are concerned.

ii)

It is really hard to make any kind of meaningful observations even based on good quality pics; frankly they just cannot convey what an actual physical inspection can.

Ficus are incredible in their capacity to regenerate and revreate themselves even in the face of much worse damage than you show and describe…however (and it really is an important caveat) when trees have been planted to provide visual amenity in a formal setting the retention of that near perfect form (health and vigour) tends to take precedence over other considerations.

As to whether it is appropriate to be considering replacing relatively young trees in this circumstance…if it were me I hope I would be looking at all those aspects of the trees’ contribution and weighing up whether in my opinion the trees were likely to be able to recover from the damage..and the predictable future damage from kerb and channel works.

Replacements planted further into the park a few years ahead of any removals might engender wider community support and confidence.

iii)

I’m not familiar with any research on the subject of Glyphosate (active ingredient of Roundup) poisoning but have encountered poisoning of trees with this herbicide on several occasions.

Advice based on your description and the 3 photographs obviously has its limitations.  The trees in photos 2012 and 2012iii show signs of a prolonged recovery and stand a good chance of developing healthy crowns.

If the trees were going to die, I would expect death to occur within either the first month in the case of a fatal dose, or within the first 2 years if the dose was non-fatal but resulted in defoliation followed by poor re-growth that subsequently declined and died.  In the case of threes in the 2 photos, the re-growth has persisted and appears to be thriving, which indicates that the trees have a good chance of survival.

iv)

They could be restored but they would need to outsource in order to find arborists who actually understood tree anatomy and physiology because, based on recent efforts, it appears that they have a total absence of such skills at NCC. You can quote me.

And a friend in Marrickville tells me the Council there is working at saving two Hill’s fig trees that have been poisoned. One is responding. How heartening to know that not all Councils have such a limited repertoire when it comes to allegedly poisoned trees.

And Saving Our Trees has a wonderful post on Canberra’s recipe for poisoned trees:

http://savingourtrees.wordpress.com/recipe-for-poisoned-trees/

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One Response to “Arborists’ opinions on poisoned Adamstown trees 15.4.2012”

  1. Will Says:

    As I understand it, Glyphosate (Roundup) is absorbed by green leaves then taken into the sap system where it then damages or kills the plant. Glyphosate is inactivated / adsorbed by soil.
    I do not understand how council spraying glyphosate to kill weeds around a large tree trunk can kill/damage the tree.
    Unless holes were drilled in the trunk and glyphosate placed directly into the sap stream or there was a lot of living fig leaves sprayed at ground level. Or there was a huge herbicide mist that made its way into the canopy?
    The council explanation doesn’t seem plausible to me.
    Has someone deliberately poisoned these trees with another herbicide? Or did council use another (soil active) herbicide? Triazines were commonly used to clear weeds but is no longer for this use. Did council take samples of the “poisoned” trees for herbicide analysis as many council do when they are concerned someone might have poisoned amenity trees? Or did council workers use a non approved (soil active) herbicide?

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