Monday, 13 May 2013

From small seedlings big trees grow 

And may need to come out ... at great expense!

Blackwood Wattles, Acacia melanoxylon, are a case in point.  I once thought them attractive, a good example of a tall wattle, with dark green "leafy" foliage, actually flattened stems that look like a true leaf, that comes originally from parts of Victoria and Tasmania.  They do well in our South West particularly in moister gullies and on south facing slopes.
Blackwood wattle on right of the photo, quite a tall 
tree with, even then, signs of one of its undesirable
characteristics, namely, suckering.

Possibly about 25 years ago, a number were planted by previous owners as innocent-enough-looking seedlings.  It was the age of Permaculture, self-sufficiency and recycling.  These trees were put in as a tree crop with the hope that down the track they would provide timber for furniture or, at the very least, firewood.  

My first impressions of them were that they were desirable trees that were recommended by farming friends.  I was pleased to find them on my 1.9 Ha in Balingup that I bought in early 2006.

A few years later, in July 2008, I began to have reservations about them when during a winter storm, the tree, pictured left and below, came down rather spectacularly and as a total surprise, because I had had the impression that they were more long lasting than most wattles.
This Blackwood wattle literally collapsed and spreadeagled
itself across some 30 metres during a storm,  just missing 
the big shed shown to the right of the picture.
The Blackwood wattle just missed the Big Shed.
It, of course, happened at the start of a weekend and we needed access to our sheds and the driveway, so we had to engage expert help to remove the remains of the tree.  It cost us around $1000 to clean up.

It was sawn up and the smaller material mulched, the we cut some fire wood, took loads to the tip and burnt some logs.  Some was not usable because it had rotted at the base and hosted many borers that had been having a good time for many years.

When I realized that Blackwood wattles were also likely to be quite inflammable over summer with their incessant dropping of litter, small twigs, seed pods, larger branches and indeed the whole tree, I reviewed my opinion of this type of tree.  In addition to suckering they also grow prolifically from their many seeds.  I decided to remove them over time rather than try to prune them as this was quite expensive anyway and the tree would still keep growing.

Removed in February 2013, these
Blackwood Wattles are no 
longer a problem.
We had another storm in June 2012 and one large Blackwood Wattle leant over onto another one.  That was it!  The rest of them, about half a dozen which were casting a dense shade, a problem especially in winter, were removed at considerable expense, but now they are no longer a problem.  Importantly they do not pose a fire hazard any more.

During the Festival of Country Gardens on the Arboretum Amble in early May, the owners of the property with this wonderful assortment of trees told how they had decided to remove a row of Blackwood Wattles because of their undesirable traits.  I agreed wholeheartedly with their sensible decision.

Borer signs in felled Blackwood Wattle.

This Blackwood Wattle had rotted out at the base and was
leaning into another after the 10 June 2012 storm.    Note 
the regrowth, they have ways of surviving.

And the moral of this story is:  
Don't plant Blackwood Wattles in gardens in the first place.