About four-fifths of the canopy gone

About four-fifths of the canopy gone & every tree is the same.

A couple of weeks ago I drove down Carrington Road Marrickville South & noticed that the row of around 13 heritage Canary Island palm trees had been pineapple-pruned.  I was pretty sure this had been done to rid the Ibis from these trees.

I wrote to Marrickville Council & asked for reasons why they pineapple-pruned these heritage trees.  Their response included –

  • “Dead Frond Removal.  On several occasions dead fronds had fallen on cars & the road, removing these was a safety priority.”
  • Canopy Lifting because of a disease called Fusarium oxysporum. “Disease management is based solely on disease prevention.  The Australian White Ibis is identified as one of the major transmitters of Fusarium within Date Palms, as such reducing their use of these palms by removing horizontal branches for them to land on is a key way to combat the spread of the disease.  Councils Biodiversity officers where [sic] consulted with several months prior to the work being undertaken to address any concerns over White Ibis impacts. The trees where also monitored several weeks in advance of the pruning taking place to ensure the Ibis where [sic] not using them. White Ibis nesting season is between June to January – we delayed work, which we initially wanted to do in September due to several dangerous branch drops, to avoid disrupting the Ibis.”

I know for a fact that the Ibis live in these trees all year round & were already doing so when I moved to Marrickville in 1996.  Every night you could watch the Ibis return to sleep in these trees.

I wrote back to Council & asked for any academic or similar publication or weblink that discusses Australian White Ibis transmitting Fusarium in Canary Island palms.   Council’s response was to offer me a chat to talk, but did not provide any references.

Despite reading extensively on Fusarium, I found nothing that said birds, including Australian White Ibis, transmit it.   In fact, every article said that the spread of Fusarium is through pruning, stump grinding & transplanting & soil water.

Cutting implements are supposed to be sterilized between working on each palm tree & experts even suggest using a new chainsaw, lopper, pruning shear, handsaw for each palm.  Since chain saws are nearly impossible to sterilize, hand saws or clippers should be the only tools used to cut off palm fronds.”  http://bit.ly/1h7KJpb

“….. pruning should be restricted to removal of only dead or dying leaves. Severe pruning, such as “hurricane cuts” or “pineapple cuts,” weakens trees & increases the risk of pathogen transmission.”

Pruning should be viewed as a risk factor for Fusarium wilt disease transmission & not as a benefit to the Canary Island date palm. While this is an extraordinary measure, it is inexpensive disease prevention management for extremely valuable palms.  A mature Canary Island date palm that has died from Fusarium wilt is expensive to remove & expensive to replace. It is certainly more economical to prevent the disease than deal with the deadly consequences, especially if there are multiple Canary Island date palms in the landscape.”  http://bit.ly/1cFJ5Kf

“Extreme pruning causes loss of important nutrients. When trees and palms have leaves that are beginning to die, certain nutrients (including potassium) are put into a soluble form & pulled out of the older foliage and usually sent to new growth. Extreme pruning done on a regular basis has been shown to be fatal to certain species of palm owing to nutrient deficiencies. Palm fronds should not be removed if they still have green on the leaflets or midrib. They are still manufacturing and supplying food to the palm.http://bit.ly/1h7KJpb

Another problem with pineapple pruning is that the new fronds are soft & susceptible to wind damage, so more falling fronds.  Old dead fronds hang on the palm for a very long time.  Council could have chosen to prune these dead fronds long before they started becoming a safety issue.

I also contacted the Veteran Tree Group Australia.  They said, “We are not aware of any studies or publications that link Ibis as a vector for the spread of Fusarium.  Pineapple pruning or any severe pruning involving the removal of live foliage is not an option that we would recommend in management of mature or veteran Canary Island Date Palms; this can weaken the palms and exposes them to a greater risk of infection.  Pruning of mature palms should ideally be limited to removal of only dead or fractured fronds for the purposes of risk mitigation in public areas.  http://bit.ly/1k45g1s

A shadow of their former glory

A shadow of their former glory.  There are about 13 palms along this side of Carrington Road.

Compare with the palms at Laxton Reserve Dulwich Hill

Compare with the palms at Laxton Reserve Dulwich Hill