Above- Shiraz this week has fully coloured and completed verasion (EL 35). Note the dappled light on the fruit.
Below- Balanced Shiraz at harvest (2004 Vintage).
A vine can be described as ‘balanced’ when vegetative growth and fruit load are in equilibrium. Other indicators of balance include early maturity, ability to store good reserves of carbohydrate, low shoot variability and cessation of shoot growth by veraison. In order to achieve balance in the current season, vines must have an adequate number of active leaves (shoot to fruit ratio) to sufficiently ripen fruit.
Vine balance can be assessed by a number of methods. The most common is the measurement of fruit weight to pruning weight ratio. Balanced vines have a pruning weight ratio in the range of 5 to 10:1(Dry et al, 2004).
The second method is the measurement of active leaf area per gram of fruit, expressed as cm2/g. The optimum active leaf area for balanced vines varies and may range from 6 to 25 depending on variety, climate and trellis type. For cooler climates such as McLaren Vale, vines may be considered balanced if leaf area per gram fruit is between 12 and 15 cm2/g2 (Winter and Whiting Aust. Viticulture Jan 2004pp 70-73).