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Viaduct Creek

New Zealand Tree Grower August 2016.

The second part of the field day on Monday was to visit Viaduct Creek owned by Glenn Crickett and Catherine van Paassen. When they bought it the land was rough grazing with gorse, sphagnum and just a few tracks. Planting began in 1997 with blackwood, radiata pine and Eucalyptus nitens for firewood.

 The original plan was explained by Glenn, which was to grow firewood on a short rotation using E.nitens in a form of agro-forestry. However, he also decided that this eucalypt could also produce timber which would need a different management system.

The blackwood will be the dominant crop as the eucalypts are mainly for his firewood business. He can sell eucalypt firewood at $90 a cubic metre and reckoned that he can make more money as a continuous firewood operation that doing anything else with his eucalypt. However, he is interested in developing more with this timber if he can find suitable markets.


We first walked among the eucalypts which were 15 years old, pruned to six metres and going to be thinned in the following spring, some of the wood to be milled for timber and the rest for firewood The agro-forestry look of around 70 or 80 stems a hectare is what Glenn wants for the whole property so that there is plenty of pasture for grazing.

Initially the eucalypts were planted on the flat ground but then it was decided to mound the ground with a digger and to make these mounds eight metres apart. The land between the trees was flipped after about five years to improve the drainage, help develop better root structure and avoid the trees being blown over.

Planting involved putting three trees close together and after six years keeping the dominant tree of the three, with the others removed. The dominant trees are eventually pruned to five or six metres. In hindsight Glenn said the mounds should have been at 12 metres apart as eight metres is a bit close for the fully grown trees

Into the blackwoods

We then moved on to have a look at the blackwoods. Glenn explained that these did not grow well at first after being planted in 1999 inter-mixed with some E.nitens and E.mearnsii. In 2014 an excavator was used to flip the ground and break through the ironpan two metres below. With a drier environment due to better drainage and the addition some fertiliser, now at 14 years old they were looking a lot more like blackwoods should look.

Glenn said it had been a bad start but was picking up well, helped by adding plantain which is deep rooting and also dries the ground. There was such strong competition from the eucalypts used as companion planting that he would ‘physically restrain’ anyone who tries to companion plant in the future.

Why bother with blackwoods?

Glenn said that he continues with blackwoods because he likes them. He used to prune the blackwoods in the same way that he pruned pines years ago when he worked in forestry, but it did not seem to be such a good idea. Then he saw a Tree Grower article by Ian Brown and thought ‘Ian was dreaming or on to something’.

He eventually managed to visit Ian and had a long discussion about pruning blackwood. However, what he was trying to do still did not seem to work. Then Ian Nicholas dropped for a visit about 10 years ago and introduced him to gauge pruning.

He now uses gauge pruning along with Ian Brown’s leader control and the combined approach seems to work. He admitted he will need to do some crown pruning when the final eucalypts have been removed and there are still too many double leaders on the blackwood with trees competing with themselves. Originally every blackwood was going to be pruned to five or six metres, but after Cyclone Ita knocked over lots of trees on the West Coast he decided that around 4.5 metres would be enough.

Pruning safety

In the discussions among the trees, safety when pruning was raised because it is not easy and people can get careless. Glenn said that there is a range of ladders and safety harnesses out there now which are excellent and that you would be ‘bloody stupid’ not to use them. He also added that you need to take your time, allow for fatigue and drink lots of water. It was excellent safety advice to finish the day.

Eucalypts pruned to six metres
A good stand of blackwood
Ian Brown providing some advice
Some experimental eucalypts
Admiring some of the blackwood

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