Joy K. Dick

Copyright © 2008 Australian Society of Viticulture and Oenology Inc.Own-rooted Shiraz, spaced 1.5 m apart in 2.75 m wide rows, were compared under five different training systems in the Barossa Valley, South Australia over five seasons starting 1995-96. Our objective was to determine how training affected fruit composition and crop yield in a context of efficient vineyard management. Training systems were: (i) low single wire (LSW), in which vines were trained to bi-lateral cordons, 1.0 m above the ground, non-shoot-positioned; (ii) high single wire (HSW), a higher cordon (1.8 m) version of LSW; (iii) vertically shoot positioned (VSP); (iv) Scott Henry, where canopies of alternate vines were cordon-trained and shoot-positioned upwards (SHU) or downwards (SHD); and (v) minimally pruned (MIN), the same as LSW, except vines were not annually spur-pruned. Crop yields (kg/m of row), over four seasons, averaged 4.9 (MIN), 2.9 (combined Scott Henry), 3.2 (VSP), 2.6 (HSW) and 2.9 (LSW). The greatest year-to-year variation in yield occurred with MIN and Scott Henry training. Crop weight of SHD vines was inferior to that of SHU vines in two seasons due to fewer shoots and bunches per vine, and to fewer bunches per shoot. Individual berry weights (g) were consistently least with MIN (0.89), and greatest with VSP (1.17). Fruit from all training systems exhibited similar rates of sugar accumulation during two seasons in which repeated measures of fruit maturation were made. Excepting the relatively light yields observed in 1999-2000, sugar accumulation was delayed in MIN vines, relative to other training systems, even when MIN harvest was delayed up to two weeks. The delay is most readily explained by the greater crops of MIN vines. Berry total anthocyanins and total phenolics concentrations (mg/g berry fresh wt.) at harvest were not greatly affected by training system. Berry anthocyanins and total phenolics exhibited a negative relationship with crop/m of canopy and a slight positive relationship with bunch exposure when evaluated across all training systems. Experimental plot soil depth and water availability affected cane pruning weights, yield per vine, berry weight, and canopy characteristics. LSW, HSW and MIN training systems all provided good yields of high quality fruit, although MIN did have a tendency to produce excessive crops in some years. VSP and Scott Henry training were less attractive due to their inherently greater canopy management requirements.Tony K. Wolf, Peter R. Dry, Patrick G. Iland, David Botting, Joy Dick, Ursula Kennedy and Renata Risti

This paper reviews the subject of canopy management with an attempt to develop principles. These principles provide guidelines for canopy surface area amount; spacing between canopies; within canopy shade, especially for the fruiting/ renewal zone; balance between fruit and shoot growth; and uniformity of location of fruit/renewal zones, shoot tips and cane bases. Field techniques of point quadrat analysis and canopy scoring are introduced as an aid to defining problem canopies. These techniques are cheap, quick and effective. A set of twenty-one numeric indices and descriptors to assess winegrape canopies is then presented as a winegrape canopy ideotype, which can be further used as management guidelines. Recent publications are reviewed from various aspects of canopy management. These include vigour control, shoot trimming, leaf removal in the fruit zone and training system responses. The paper concludes with presentation of the authors' unpublished data on the effects of canopy microclimate on yield and wine quality. The trial was conducted with the cultivar Cabernet franc on a deep, fertile soil in a cool, high rainfall region. Canopy division using the Ruakura Twin Two Tier doubled yield compared to dense, vertical shoot positioned canopies which are common in New Zealand. Shade caused reduction in all yield components, and also delayed fruit ripening and reduced wine quality. Similar results were obtained by comparing fruit production at different heights with the Te Kauwhata Three Tier trellis system, where lower tiers were shaded at the canopy exterior. The results confirm that grape yield and wine quality can be simultaneously increased by improved canopy management of shaded vineyards.