Category Archives: Management

It’s planting time. Is anyone thinking of planting commercial blackwood this autumn?

If so please let me know – I’d like to help.

It has been a very dry season so far. Unless we get some rain in the next few weeks it may be too dry to plant in some places this year.

Remember the first rule for successfully growing commercial blackwood is selecting the right site. If you are unsure I can help.

We can actually use the current dry season to help identify good sites. If your proposed planting site still has green grass then that is a very good sign that there is plenty of summer soil moisture. These sites are the best for getting good blackwood growth.

As for the planting regime my recommendation is to keep it simple. Until we gain more experience and confidence in growing commercial blackwood then keeping things as simple as possible is the best place to start.

If you are planting this autumn then your site preparation should be happening now:

1. Protection from browsing by all herbivores is very important. Unless your site is more than about 1 hectare in area, you will need tree guards for each tree. For larger areas you might consider mesh fencing. Work out the costings and see what is your cheapest option – tree guards or fencing.

2. Mark out your site with a 7 x 7 metre grid. This equates to 204 trees per hectare. With this tree spacing there will be no need to thin. Not every tree will survive or prosper with good management I would expect better than 80% success.

3. Do weed control in a 1 metre radius circle at each grid point.

4. You should now be ready to plant.

The best time to plant is from late March through to early May. Again, rainfall and soil moisture will be critical to watch in the coming weeks.

Commercial blackwood plantation – perfect land use and investment for that difficult, weed-covered slope.

Research has shown, and certainly my own experience agrees, that blackwood growth rate and stem form are positively correlated. The faster the blackwood grows, the better the stem form and the less pruning is required to create a single straight-stemmed tree. Good growth rates are achieved by good site selection, good establishment techniques and good ongoing management.

But some pruning is inevitable. For a variety of reasons blackwood loses its growing tip and then goes on to develop multiple leaders that need to be managed. Here’s a recent example of form pruning to help keep these blackwoods on the straight and narrow. It’s not hard work, and can be enjoyable.

The following excerpt on blackwood pruning comes from the NZFFA website:

(http://www.nzffa.org.nz/farm-forestry-model/resource-centre/farm-forestry-association-leaflet-series/no-20-australian-blackwood)

There has been an increasing acceptance that pruning is essential in managing blackwood. The method has no resemblance to pruning radiata pine; it is not difficult, but requires a commitment to visit the trees annually during the establishment of the 6 metre stem. There are two stages, which overlap:

·         form pruning

·         clearwood pruning

Form pruning

Blackwoods have poor apical dominance. Periods of stem growth are interrupted by abortion of the shoot tip. When growth resumes, several shoots compete for leadership. A blackwood stem is therefore formed by segments of straight growth which are interrupted by zones of disturbance which contain double or multiple leaders. The aim of form pruning is to identify and remove these competing leaders while they are still small (< 3cm diameter), and this requires an annual pruning visit during the formation of the 6 metre butt log. Long-handled pruners are useful.

Clearwood pruning

The aim is to confine the defect core. Clearwood pruning is done annually, starting at about year 3, and is complete by about year 8. It is carried out in stages, in which the largest branches on the stem are removed first, using a 3cm calliper. The trunk is then pruned to the diameter of your defect core (10 to 12cm). No more than a third of the foliage is removed at one visit. It is recommended that about 3 metres of the crown is left after each lift. Ladders that grip the trunk should not be used.

Perhaps not the best description of clearwood pruning. I would define the aim as controlling side branching, and then to progressively removing all branches from below to a height of 6 metres, while retaining about 3 metres of green live crown after each pruning.