Vineyard posts go chemical-free

However, it is the Australian drought which has driven the innovative Victorian company to seek greener pastures in New Zealand.

Plastic Pole Vault Property's manager, David Macdonald, has been in Marlborough introducing the posts to expanding vineyards. The company produces an untreated pine post encapsulated in recycled polyethylene.

"There is a big push to move away from treated timbers, particularly in organic vineyards," Macdonald said.

In 2003, the company worked with Fosters Group to come up with the alternative post. They put 12,000 of the new posts in 30ha in the Barossa Valley. Since then, about 120,000 of the poles have gone into Australian vineyards and olive-growing properties. So far, the feedback has been positive, said Macdonald.

The company has plenty of production capacity and Macdonald said it had come to New Zealand mainly because of the Australian drought. "The Australian market is absolutely on its knees because of water allocations, and this year is looking just as bad as the last couple. We are looking for an area that is drought proof," he said.

The posts are being evaluated for use in oyster farms. Trials are under way in Australia and the company has also sent its posts for evaluation by a North Island company developing a big oyster farm.

It has also found opportunities in South Island vineyards.

Macdonald has been amazed at the extent of vineyard development in Marlborough. "This would be the fastest-growing wine area in the world. It is spectacular, what is happening," he said.

The posts, distributed through Aghire, had been well received here as a viable alternative to chemically treated posts, he said. They come in two sizes -- 83mm and 125mm diameter. The plastic used to encase the untreated pine is recycled from irrigation tubing taken from vineyards all over South Australia and sent to a recycling facility. A UV stabiliser is added to the plastic to give it a long life -- the posts are expected to last at least 20 years.

It costs $NZ16 for the plastic-encased post, compared with $9 for a normal timber post. However, cost is not a main factor, said Macdonald.

"We are more competing with steel or solid plastic or other chemical-free posts. If someone is happily using treated pine, then we have no chance of selling them our posts. These are geared to other people."

The drive away from chemical posts was firstly because of leaching into the soil, but also because of the disposal of broken posts, he said. Posts get broken by mechanical harvesting, and because they are chemically treated they cannot be burnt or buried.

In Australia, corporate wine companies were stockpiling significant numbers of posts because they contained arsenic. Because they were not allowed to put them in the soil, they were building sheds or concrete slabs for them, Macdonald said.

In Napa Valley, in California, chemically treated posts were being phased out and it was a worldwide trend in vineyards, he said.