Tree talk discusses non-treated timbers

Durable rather than treated timbers will be the subject of a field day in Bulls later this month.

Durable rather than treated timbers will be the subject of a field day in Bulls later this month.

The Middle Districts Farm Forestry Association is staging the one-day event on October 28 to highlight and promote the cultivation of trees that a much more eco-friendly.

A spokesman for the associaiton said naturally durable timbers had been getting increased attention in recent years as some of the problems with treated timbers were recognised. Those problems included tanalised wood which were traditionally treated with a mix of copper, chrome and arsenic (CCA).

It was this chemical cocktail of CCA-treated word that created problems. Burning the treated timber left very toxic ash and the volumes were excessive in landfills. And organic farming rules often forbid use of treated timber.

"Naturally durable timbers rot from the outside in rather than, potentially, from the inside out as treated timber can, meaning failure may be sudden and unexpected. And of course they can be burnt in any fireplace," the spokesman said.

He said New Zealand can grow a wide range of naturally durable timbers and farm foresters have been growing them for many years, although seldom on commercial scale.

Denis Hocking's property near Bulls had one of the more extensive collections of high durability timber species where 20 different species with Class I durability timber and an equal number of class II timbers were successfully growing on sand dune country.

The Hocking property will be the venue for the field day where site requirements and performance of the different species will be demonstrated and discussed, along with the technical aspects of wood durability.

"This will be an important day for anyone interested in growing, or using, naturally durable timbers for uses ranging from decking and outdoor furniture through to fence posts and shed poles," the spokesman said.

The field day starts at 10.30am and will finish mid-afternoon at "Rangitoto", 370 Parewanui Rd, Bulls. There is no charge but those attending should bring lunch and outdoor footwear.

For more information phone 06 322 1254 or email: jdhocking@xtra.co.nz.