Growing Blackwoods (acacia melanoxylon)

Thanks to Alan Huggins (who pased on the invitation) yesterday (27th April) I attended a Blackwood field day in the rolling hills of the Warragul area. This was part of the 4th International Blackwood Workshop and included experts from Tasmania, NZ and even from as far away as Hawaii.

The field day began with a visit to John Goy’s property. John is establishing seed orchard for various varieties of Eucalypt as well as Blackwood.Seed was from the CSIRO Tree Seed Centre and Forestry Tasmania. John was testing 58 families/provenances in an area of .843 ha. Trees were planted every 1.5m in rows 3.5m apart (1905 stems/ha). Preparation included deep ripping to one metre, mounding, and then cultivation of the mound.

The trees were planted in August 2002 and were 4 years old. There was considerable discussion about the merits of assessment criteria based on height, diameter and form. The photo below shows John with some of his plantings (not the seed test area) in the background.

Discussion centred on whether form was genetic of environmental. Ian Nicholas form N.Z. was of the opinion tht if you had to work on a tree then you hould get rid of it.

We then moved to Lardner Park, West Gippsland where several papers were presented on the results of genetic trials and tests of different stem/ha concentrations. The conclusions can be summarised as follows:

1. Seed provenance appears to have little or no bearing on form in other words straight trees do not necessarily come from straight trees.

2. There do not appear to be any clear predictors of wood density and colour. Fast growing trees are not less dense than slow growing trees - nor lighter in colour.

3. The amount of light coloured sapwood is directly proportional to the size of the crown

4. The best overall result i.e. density, trunk diameter and timber volume results from a stem/ha concentration of about 200 stems/ha gave.

The group then moved to a 0.5 ha plot of 20 year old Blackwoods where one had been cut down. A chainsaw mill was used to open up a log and examine what happens to pruning wounds inside the log. It is important to be careful not to let bark tear or rot can set in. Plantation management was discussed and the importance of healthy crowns with enough room to spread laterally was demonstrated.

I (Simon Pockley) have a folder of notes and conference papers for anyone interested in knowing more about growing acacia melanoxylon or hearing more about the field day.