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Wood, steel and concrete posts on offer:
vineyards spoiled for choice
By GRAHAM HAWKES

With larger harvests being lifted from New Zealand's vineyards, problems with a strong New Zealand dollar affecting exports, and worries of a global wine glut - the issue of arsenic leaching from vine posts has taken a back seat lately.

That's been helped by the lack of any 'smoking gun' scientific studies that could give treated timber posts used in vineyards a bad name. In Marlborough in particular, one or two official reports have tended to downplay concerns, and producers of treated timber vineyard posts we spoke to during the preparation of this article have been quick to emphasise that.
But in a number of countries around the world, worries over the potential for leaching of preservation chemicals from treated timber into soils are growing.

Defining the exact legal restrictions on the use of CCA, or copper, chrome, arsenate-treated timber in countries around the world is beyond the scope of this article. However, its reasonable to think that increasing suspicion of the health risks from this sort of timber being used in the growing of any food or drink products might one day have an impact on the production of wine in New Zealand.

Companies producing steel or concrete vineyard posts have pointed out to us that companies adding to the already significant quantity of treated-timber vineyard posts in this country have no guarantee that their decision will prove to be the right one.

Keith Guest from Industrial Tube Manufacturing, one of the companies producing steel vineyard posts in New Zealand, says the key thing right now for wine industry people looking at the type of posts and trellising they will put in place, has to be the future contingent liability of that decision.
"Europe has already put in place bans around the use of arsenic-treated timber in any type of food production - because of the leaching issue," he says.

"Looking into the future, there may come a day when certain export markets important to New Zealand's wine industry might not accept wine that has any trace of timber treatment chemical in it.

"It could be that local wine growers in countries where chemically treated timber is not acceptable, might one day be looking for any way to protect their markets against products coming in from elsewhere. They could lobby to their governments on the fact that, hey - we don't have treated timber, but these guys do - please keep their wine out of the market.

"It could be that decisions in these countries will be made on the basis of politics, not necessarily on scientific evidence."
Keith Guest says another, related aspect is that that one day in the future, when timber posts break in New Zealand vineyards, a significant cost might be imposed on disposing of that timber.

"Not right now, but looking into the future, this could become a major issue that impacts on the decision of what posts a vineyard buys."

Industry people we spoke to who are in favour of non-timber posts, mentioned trials by wine industry companies that have shown excellent results with steel in the vineyard - and there's no doubt that one or other producers are achieving significant results from programmes of research and development into steel and concrete post products.

Keith Guest's Industrial Tube Manufacturing company has in recent years taken a lot of enquiries from the industry about steel posts, particularly when the leaching issue first appeared.
"We started working with industry contractors, discussing issues including the properties of existing steel posts in the market, and their difficulties, we also looked at the good things about timber and then tried to come up with a product that got around the bad things about steel and got around the leaching issue," he says.

The company looked to get around the problem where in strong winds, with a full canopy of vines in place, some steel posts have failed.

He says the company elongated its own post's shape to give better strength across the row where it is needed. Another major consideration was the bearing surface in the ground, which was widened, to better anchor it against the strength of wind on the trellis.

"We also went away from putting holes into the steel sections, to avoid creating weak points and sharp edges. And we went to having trellis wire attachments put onto or around the post rather than into the post, so that the steel kept its integrity. Then we added a galvanised coating inside and out."

Keith Guest says another benefit from a steel post is its ability to stand up to rough treatment from a mechanical harvester.
"Traditionally it's estimated that a harvester going through a vineyard will break 5-10% of timber posts at the first harvest and 2 per cent of the timber posts each harvest there after. As timber dries out, it becomes brittle and the harvesters of course go down a row rattling the grapes off the vines - they're beating the vines. Our steel posts deliver virtually a zero attrition rate on posts during the harvest."

He maintains his company's steel products overcome the problem where wider-section timber posts prevent a mechanical harvester getting at the fruit - leaving quite a lot of fruit on either side of the post. We've done some calculations and it can be between 125kgs and 250kgs per hectare of grapes left when a mechanical harvester comes through a wooden vineyard, versus a steel post vineyard, where it gets virtually all the fruit."

All these positives are genuine points in favour of steel posts - but there's one aspect of steel that its backers readily admit is not so positive. The reality is that pricing for steel posts is generally higher than that of timber.

The volume of steel going into China in recent years has seen the price of the raw material steadily rising on world markets, and New Zealand has not been immune to that. In contrast, timber prices have maintained an 'equilibrium' for several years, one steel post provider told us. The strength of the Kiwi dollar has also affected the ability for steel posts to be competitively priced. When it comes to boardroom decisions on the costs of fitting or refitting a vineyard, the issue of steel versus wood doesn't often get past the accountant, we were told.

For companies setting up new vineyards and wineries, the answer to the question - timber or steel - is often answered simplistically by the figure next to the dollar sign.

One supplier of steel posts told us: "They often say, we like your steel posts - it's a great design and we understand about the saving in costs that will accrue, but right now our set up costs are snowballing and we need to restrain them."

Barry Bunting from R C Macdonald Ltd in Christchurch says there are a number of very strong reasons why steel posts should be a 'given' for new wineries, especially smaller or boutique wineries.

In Australia, there is an on-going problem of how to get rid of broken, treated timber posts each year from vineyards. Barry Bunting, along with several other industry players said it could easily become an issue for this country.

He says there are also still "undercurrents" regarding CCA treatment of the posts New Zealand uses in the wine industry, and the issue of leaching of residues into the soil - but he says the bigger wine companies, who could lead the way in this area, are not doing so.

"What could happen is that a country like Canada, or the United States, or the EU might decide that they will no longer import wines made in vineyards that use treated timber. That's a real possibility at some time in the future," he says.

'Okay, we still only produce about 2 per cent of the world's wine consumption, and that means we are a very small player in the scheme of things. But there are a lot of people with a lot of money invested in the wine industry in this country."

Andy Leonard of Nelson-based Goldpine Industries Ltd says the wooden post is clearly the most accepted type of vineyard post amongst wine industry buyers. However, he makes clear that the steel and concrete post providers are not the only ones who have been trying to lift on the innovation front.

"There are a few trends within the wood industry. One is a shift away from the traditional half-rounds to quarter rounds, mainly because of their strength and price. They're like a larger strainer post cut into four, but they have the same volume of wood in them because the timber is taken from further down the trunk of the tree, where there is a higher proportion of higher-density wood."

On the chemical issue, he says there have been a lot of independent tests that have proven there are no issues with the chemical being used.

"It's sort of died away in the last year or so. We are getting fewer questions from our customer base."

Asked about the possibility of other countries using the timber treatment issue as a way to restrict access for New Zealand's wines, Mr Leonard said he believed the chances of that happening are "pretty slim".

Outside of the technical and environmental issues surrounding vineyard posts, Fencesteel Ltd is busy marketing a new product, the Z47 steel post.

Designed and manufactured by the Auckland-based company, it is marked out on the market by its z-shaped cross-section.

The posts are strength pull-tested to more than 200kg, which Fencesteel says is due to the post's unique shape and a reinforcing sleeve which provides extra strength at ground level - while still allowing enough flexibility to withstand wind loading and the stresses caused by mechanical harvesting.

The company says another major feature with the Z47 is its 'wire-friendly tongues which hold the wires in place. The tongues have smooth, rounded corners for abrasion-free wire retention, and the design allows easy lifting of foliage wire.

Fencesteel Ltd says the posts are up to 15 per cent faster to install compared to their wooden counterparts. Once the posts are driven into the ground, the trellis wires can be simply strung up, without the need for additional nails and clips.

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