ISHS Acta Horticulturae 473: International Symposium on the Importance of Varieties and Clones in the production of Quality Wine
VARIETIES AND CLONES USED IN AUSTRALIAN WINE GRAPE VINEYARDS |
| Author: | John V. Possingham |
| Keywords: | clonal selection, viruses, viroids, yields, wine quality, vine improvement societies |
| DOI: | 10.17660/ActaHortic.1998.473.1 |
| Abstract:
Grapevines came to Australia some 200 years ago with European settlers and were used initially for the production of local table wines. Australian wine production expanded and exports to England increased after phylloxera began to ravage European vineyards but declined soon after resistant hybrid American rootstocks became available in France. During the first half of this century consumers in both Australia and England developed a preference for fortified wine of the port and sherry type. These wines were easy to produce in the warm viticultural areas of Australia and could be transported to Europe without problems. In the 1960's, 85% of Australian wine was fortified which now accounts for only about 3% of production. Over the past 5 years exports of table wine from Australia have grown rapidly and now make up a quarter of the volume and half the value of our production. The varietal mix of Australian vineyards has undergone a series of market driven changes to accommodate changes in consumer preferences. Over a period of about 20 years Spanish varieties such as Palamino, Pedro Ximinez, Doradillo required for the production of fortified wine have largely disappeared and major reductions have occurred in the areas planted to Grenache and Mourvedre. During the past 10 years local and international sales have resulted in large areas of the distinctly flavoured French varieties Chardonnay, Semillon, Cabernet Sauvignon and Shiraz being planted in virtually all of our viticultural areas. In cooler areas some Pinot Noir for both sparkling and red wine has been planted, and a recent trend is to expand the production of Verdelho, Sangiovese and Merlot. The widespread use of machine harvesting has made possible the growing of large areas of premium varieties with small bunches. Within Australia there are no restrictions to planting wine grapes and growers are able to establish vineyards on new land and to plant any variety they believe they can sell. Since the 1960's research programs aimed at both selecting from local vineyards, and importing from other countries, high yielding clones of a range of distinctively flavoured wine grape varieties have been carried out. Both local and imported clones have been subjected to heat treatment and meristem culture to remove graft transmissible diseases. These clones and a range of resistant rootstocks have been evaluated in trial plots established in viticultural areas with differing climates. Adaptability has been mainly assessed on the basis of yield and on sugar and acid content at harvest. Limited wine quality assessments have been made using small scale fermentations. Wine quality assessments are also made by wine companies as in Australia approximately 70% of wine grapes are sold by growers to wine processors. Currently the leading varieties are Chardonnay, Semillon, Riesling, Cabernet Sauvignon and Shiraz. Australia's wine areas vary from region II to region IV using the Californian heat summation system. Wines from the same variety differ in quality between the regions. Irrigation of grapevines is permitted and is virtually universal. Phylloxera is present in only a few restricted areas of Australia while fanleaf virus and dagger nematodes are virtually absent. The main rootstock used for wine grapes is the Vitis Champigni stock Ramsey which gives vigorous vines on light textured sandy soils which are commonly infected with plant | |
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