A group of South Africans visited the south of Australia last year to learn more about various vineyard techniques.
Value of mature vineyards
When the Barossa valley is mentioned in the world of wine, everyone agrees: The countryside northeast of Adelaide is the ideal terrain for great Shiraz wines. Comprising approximately 10 000 ha, it is planted mainly to Shiraz, but occasional plantings of Grenache Noir and Mourvèdre give depth. The climate is fairly hot and in mid-summer the mercury climbs to 40°C. Water is generally fairly scarce. Given these conditions, what makes the wines from the Barossa so exceptional?
The vast majority of the vineyards were initially planted to make port. Thanks to the absence of phylloxera and leafroll virus, these vineyards remained intact and the Shiraz is on average 60 years old. These mature grapevines are in balance and produce moderate size crops of exceptional quality.
According to the Australians the Shiraz blocks produce top wines only after 10 or 15 years. South Africa has a reasonable amount of mature Chenin blanc which is not negatively affected by leafroll, but the majority of red cultivars are replaced aged 20 years or even earlier, when they should in fact be at their best.
All research and protocol already exist in South Africa to combat leafroll; the challenge for the industry is to apply it to allow grapevines to advance to a mature age and to maintain them.
Increase in eutypa
The eutypa fungus has taken on serious dimensions in South Australia. It increased especially after the serious droughts of a few years ago and speculation abounds whether the water stress to which the grapevines were subjected, possibly expedited the infections. To prevent infection, pruning wounds are treated with fungicides and research is being conducted on biological agents, such as Trichoderma. Currently many grapevines are being sawed back and cordons re-established or converted to cane systems.
The South African delegation visited farms in the Langhorne Creek area where winter pruning is mechanical. In older grapevines with a fair amount of accumulation sawing back is prevalent. Such actions cause large wounds.
The effect of large wounds was clearly visible in the increase of eutypa symptoms. In such instances the wounds were treated with fungicides only.
Price determines viticultural methods
Australian producers have mastered the art of adapting viticultural techniques according to wine objective and grape price. Since labour is very expensive (about AUS$25/hour), mechanisation increases with decreasing grape prices. A top quality Barossa Shiraz vineyard that sells at AUS$2 000/ton is therefore pruned and spaced by hand, whereas mechanical pruning is used for a Shiraz vineyard in Langhorne Creek which fetches AUS$800/ton. The interest rate on the expensive capital equipment is low, making mechanisation a profitable option.
Exceptional wine quality vs small quantities
When you walk into the new tasting venue at Penfolds in Adelaide, one central theme emerges loud and clear: Quality. Penfolds is a big company. The old cellar in Adelaide crushes only 300 tons annually and tourists ogle the old cement coops that are still in use.
The bigger, newer cellar is in the Barossa where they crush more than 20 000 tons annually. Although it is a big cellar, the wines are made meticulously on a small scale. Each of the eight winemakers is responsible for his / her own wines and most of the red wine fermentation tanks have a capacity of 10 to 20 tons. The best grapes are bought in and Penfolds owns vineyards in key areas, such as the Barossa, McClaren Vale and Adelaide Hills. The iconic Penfolds Grange at AUS$850 per bottle is the flagship wine of this sought-after brand.
PHOTO 1. An example of a mature Barossa Shiraz vineyard that still produces high quality grapes after 60 years.
PHOTO 2. Sauvignon blanc grapevines in the Adelaide Hills area are being sawn back due to eutypa infection and converted to cane systems. Depending on the vigour, as many as four canes are trained to improve production in this cool area.
PHOTO 3. Large wounds where blocks were subject to mechanical pruning and sawed back cause significant risk of eutypa infection.
PHOTO 4. The effect of sawing back after a few years is serious eutypa infection and dieback.
PHOTO 5. Top quality Barossa Shiraz is pruned by hand to ensure a balanced yield.
PHOTO 6. Low grape prices for this Langhorne Creek vineyard make manual pruning too expensive. Mechanical pruning is therefore applied. Pruning by hand takes place where grape prices are higher.
PHOTO 7. Penfolds’ Grange has been released annually since the fifties. At the new tasting venue in Adelaide a bottle of each vintage is displayed.