Try to think like a grape vine’, former Lindemans viticulturist Colin Kidd would often say to his protege, Max Arney, now Southcorp’s regional vineyard manager at Coonawarra. With Mildara’s Bob Hollick, Kidd was one of the individuals responsible for the introduction of mechanical pruning to the area in the early to mid 1970s. ‘Another of Colin’s old adages was that “the footsteps of the farmer must show in a bottle of wine”; you must have that attention to detail in the vineyard’, says Arney, who now oversees more mechanically pruned vineyard than anyone else in Australia. Mechanical pruning leaves a higher number of buds per vine, but the additional shading created by the build-up of dead wood after several years of this practice means that a lower percentage of these develop. The vine will produce more but smaller and tighter bunches, which ripen towards the outside of the vine canopy, away from the shading of the main cordon. With better fruit exposure, compatibility with mechanical harvesting and reduced risk of disease, the attractions to Kidd and those like him were obvious. But the success of mechanised pruning was no overnight phenomenon. Frequently derided as the bargain basement corner of Australian viticulture, Coonawarra appeared to take its reputation as Australia’s premier red wine region for granted. Vineyard costs plummeted, but grape yields skyrocketed and usual flavours appeared in its wines. Today, with 25 years experience of these techniques, quality has again become the single focus. The companies based in the region can no longer tolerate ‘vin ordinaire’ from Coonawarra fruit. ‘We’re much more concerned with vine balance and bud numbers, and how they affect the shape and pruning regime for each vine. First developed as a poor substitute for hand pruning, mechanised pruning is now working to the extent that we are now wondering how to raise the standard of fruit from our hand-pruned vineyards to mechanically pruned levels. ‘It’s all about getting a vine to a particular size in vertical and horizontal dimension with balanced bud numbers for a desirable crop level, these days considered to be below what it was five or seven years ago. We thought in a perfect world that we could make fantastic shiraz at 5.5 tonnes per acre, but even with irrigation we’ve reduced the target to more like four tonnes per acre’, says Arney. Irrigated Coonawarra cabernet sauvignon will habitually only crop around 3.5 tonnes per acre today, directly comparable to most premium regions. Much of the region’s best fruit comes from ancient non-irrigated 70-year plus vines, whose crop level is significantly lower. Its growers have also learned to water only when vines are stressed, not to increase yields. Only a tiny fraction of Coonawarra’s 3,800 ha of vines is today pruned by hand, while much of the area is managed by simply converting the region’s standard two-tiered cane-pruned system directly to mechanical pruning. This has gradually increased the mass of dead wood between and around the two levels of canes and the wires that support them. Growers usually spend extra money to ‘finish’ the vines each winter with a rough hand-trimming to cut away unwanted bulk of wood, which impairs sunlight and air movement while increasing risk of disease. While the two-tiered cane system was traditionally pruned to leave 60-80 buds per vine, the same vines are today pruned to 120-160 buds, with a surprisingly high level of correlation between the targeted and actual bud numbers, given the relatively crude manner in which mechanical harvesting is applied. The higher levels of shading in mechanically pruned canopies reduce the proportion of successful buds to the extent that only around 75-80 develop per two metres of trellis, about the same as for a hand-pruned vine. This number, says Max Arney, is not only the target number for the in-vogue hand-pruned Scott Henry system on two wires, but since the mechanised trellis is twice as tall, there is considerably less shading. ‘The light inception in a hedged canopy in all of our premium blocks would exceed what is considered good for the new age systems of trellising’, he says. ‘Limestone Ridge is as good as you get. It’s got enough leaves to support its crop and enough light and ventilation to maintain a healthy crop, so we get very fantastically intense berry characters.’ Vic Patrick used to look after Wynn’s extensive Coonawarra vineyards before becoming head viticultural honcho for Mildara Blass. Although his national responsibilities are reflected these days in his frequent-flyer points and in the frequency of his car services, his heart, soul and home are firmly entrenched on red Coonawarra dirt. Patrick has actively participated in the mechanical vineyard experiment since its earliest days. One of the earliest criticisms of mechanical pruning was that it developed an excessively broad band of sugar ripeness around harvest time, creating both excessively under-ripe and over-ripe fruit on the same vine canopy or hedge. ‘Mechanised pruning does not increase the spread of ripeness as much as we first thought’, says Patrick. ‘As long as we’re keeping the hedges tight and growing the same number of buds per square metre as we do with cane pruning we’re okay. Fruit ripens at the normal time, with normal bunch weight and the same flavour. If it’s free of disease and you’re making smaller bunches and berries and you have a higher skin to juice ratio, why is there a problem? And crops are maintained at what you would normally have wanted your vines to yield anyway. ‘With its higher initial number of buds, a mechanically pruned vine is more likely to recover from frost. Sure it’s the cheapest way to grow grapes. But the quality still meets the standards.’ Several mechanically pruned vineyards are increasing yields by half to one tonne per acre without extra effort by leaving an extra wire or cane above the typical mechanical set-up. It is not yet clear how this affects fruit quality. Far more controversial than mechanical pruning is minimal pruning, which, as its name suggests, involves no real pruning effort at all. The canopy is trimmed during ripening and developing bunches are removed from the last three feet of the canopy above the ground, but otherwise the vines are pretty well left alone. Let’s just say the vines don’t appeal to the eye. First trialled by Colin Kidd and CSIRO’s Peter Klingliffer at Lindemans in 1979, it today accounts for less than 1% of Coonawarra’s vineyards, the major exponents still being Lindemans and Mildara. Producing an even higher number of buds than for mechanised pruning, minimal pruning also creates smaller, later ripening bunches. Yields are much the same as normal. Unlikely to be more widely adopted, minimal pruning offers large companies the opportunity to spread the harvesting of their fruit over a greater time-frame and therefore cut the congestion in the wineries. With its extreme number of buds, it also gives growers the chance to manipulate yields after the risky periods of spring frosts and flowering. But, as Max Arney says, minimally pruned vines are difficult to manage and tend to over-crop on deeper soils like Limestone Ridge. The Hand-Pruned Alternative Until its purchase of an adjacent mechanically pruned property, Bowen Estate’s vineyards were all pruned by hand. Doug Bowen credits hand pruning for his excellent wines from 1989, from what is widely considered a disastrous vintage for the region at large, most of which was by then mechanically pruned. At Leconfield Ralph Fowler is experimenting with what is, for Coonawarra at least, a radical alternative. He is planting 5.5 acres of cabernet sauvignon on an adaptation of Professor Alain Carbonnieux’s split lyre canopy concept developed at the University of Bordeaux expressly to improve the flavour and composition of this variety. ‘I’m wildly enthusiastic at the idea, but obviously I don’t have any results at this stage. Although Coonawarra fruit is sometimes criticised for being green and thin, I don’t know of anyone else using it to improve cabernet flavour in an area where it is already recognised as pretty good. We need another two years for the truth to come out’, says Fowler. ‘I really couldn’t give a damn what it costs to manage, in terms of pruning, training and hand picking, for the price we get these days for Coonawarra wine justifies getting first-class grapes into the winery. In the same breath, I’m very cautious about saying the rest of the region is wrong and that we’re heading off in the right direction. Ultimately, we’re satisfied with what Coonawarra is doing, but think we might do better.’ Hoping to run at around 120 buds per vine, Fowler anticipates better exposure of buds with more developing shoots with an ultimate gain in fruitfulness leading to an even and fairly rapid ripening. Even should Leconfield’s experiment work, Coonawarra could never go back to a fully manual system of viticulture, for the requisite labour source simply does not exist. With new wine areas to its north and east, Coonawarra would simply be competing against other vineyard developments for a small and finite pool of skilled vineyard staff.
