Life for a vigneron, like many Australians, was never meant to be easy. At year four, we decided that for ventilation reasons the fruiting wire must be lifted to 800 mm. This added advantage gave greater ease of pruning and picking which, with our modified lyre trellis, must be all done by hand. Lift the fruiting wire and the canopy height must rise accordingly to preserve the canopy area, but it meant our nets no longer reached the ground. It took the birds about 10 microseconds to work this out and we were forced to watch as they decimated our late maturing varieties. Fortunately, a lot of our crop went into sparkling wine base that year so we beat the birds to it.

We knew we couldn’t afford new nets, so now what? Blinding flash of the obvious?  We decided to stretch the nets over a number of trellis rows and at about every fourth row drop the net down to the ground and pin it. The reason for limiting the number of rows? If birds do get in, (and they will), poor old Flek the dog will be run ragged chasing them around an impossibly large area.

Next problem, how to splice the nets together along their length? Fortunately, we have perfected a number of techniques for putting nets onto the vines and removing them. This has been achieved with various frames and winding gear for applying and removing nets, so net handling is easy.

The early Sarlon nets can be joined without undue difficulty using vine ties, etc., but the later polyester nets, in which the weave is at a 45 degree angle, stretch and sag exasperatingly. We experimented with electrical ties, string, etc., without great joy. The vine ties were workable but tended to get snarled up in the net material and if dropped on the ground, were hard to find. The electrical ties were good if one had sharp enough eyesight to thread them but they had to be cut off later which meant writing them off every year.

Then another blinding flash occurred; why not use a simple hook? Where were we to get a simple hook? Prompted by the fact that a local plastics injection moulder, SVP Industries in George Town, had just produced an injection moulded piece for supporting irrigation lines, I talked to them. Yes, they could make a hook, what did I want? Experiments were carried out using wire to develop a suitable clip. Incidentally, metal clips were quickly considered inappropriate. We don’t want stray metal objects lying around the vineyard and our winery is, quite rightly, paranoiac about metal objects getting into pumps, bag presses and so on.

From these experiments, was born the Iron Pot Clip. It’s a simple design as you can see from the photograph of the prototype. The clip was very kindly milled out of plastic by SVP Industries for the trial. The production model will be moulded in orange plastic. It will be easy to find on the ground or in nets and is easy to fit which is the important feature.
Blinding flash number three was not really a blinding flash; it was more a matter of fiddling around with the nets and ways of joining them longitudinally. From this emerged the Rowella Twist method.

Instead of simply hitching the edges of the nets together edge to edge, you simply put each successive clip (hook) alternately above and below. Photograph two better demonstrates this. The end result is a tight, bird-proof seal between nets. Agreed, there has to be a clip every metre or so, but this is done very quickly with the Iron Pot Clip.

Having now joined our nets with an overhead bird-proof seal we found other advantages:

• Fewer nets were required to cover our vineyard. Three nets did the job of four;
• Access under the nets to monitor grape condition was now a matter of just walking along;
• In Tasmania, it is not unknown to have to apply curative sprays in late vintage. This is difficult or impossible with a tractor-mounted spray once nets are on. This was now much easier, particularly as it is efficacious to do this with a backpack or hose fed hand piece (at $3,000/tonne the effort is worth it).

The problem of joining nets solved, the next step was to determine how the nets were to be anchored at ground level every fourth trellis. We decided to stretch a wire along the ground every four trellis rows permanently anchored and tensioned. The net edge is simply passed under this and a U-pin driven in every 5 metres or so pinning the wire and the net to the ground.

It is important, also, to keep this wire and the net away from the canopy and bunches, as birds will peck through the net if it is lying against the fruit.

We are experimenting further with these pins. Experiments with rubber padding look encouraging, coloured, of course, for locating the pin. The rubber reduces the damage to the net when driving the pin into the ground or pulling it out. The cost of these pins, which have an indefinite life, is around 16 cents. The cost of the pad is yet to be established. Not a great expense as only 250 or so are required per hectare. We are also trialling double wires to better trap the net edge.
There is another plus from all this work. It may be peculiar to Tasmania, (although I think not) but it is not at all unknown for cyclone-like air movements during strong winds to pick up nets that have been simply draped over trellises and whisk them up 80 plus metres before dropping them back on the vineyard. One vineyard owner had to cut down the surrounding trees to recover his nets! With the Iron Pot Clip this is unlikely. Along the trellis, clips can be applied at, say, 5 metre intervals. In addition, the U pins/wires will anchor the net down.

The practices outlined are not without cost, but what options does a vigneron have? At $3,000/tonne it’s all worth it. The Iron Pot Clip will be available for next vintage at about 2-3 cents per clip. I welcome enquiries about the clip, the padded U pins, and the Rowella Twist technique. The cost of the U pin and pad is yet to be established.

For further information contact Roderick Cuthbert at Iron Pot Bay Wines or SVP Industries, PO Box 204, George Town, Tasmania, 7253, Phone: (03) 6382 1844.
Email: srf@svpindustries.com