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The Canberra District


Canberra District GIThe Australian Geographical Indication "Canberra District" was entered in the Register of Protected Names on 9 February 1998 in response to a direction received by the Registrar from the Presiding Member of the Geographical Indications Committee acting under Section 40Z of the AWBC Act 1980.

Map used with permission from Wine Australia


To a large extent, the emergence of the Canberra District can be seen, as described by Nicholas Faith in his 2002 book "Liquid Gold" when discussing the making of good wine more generally, "as a result of geology, geography, history and the sheer bloody-mindedness of some key individuals."

Brian and Janet Johnson's " Wines of the Canberra District - Coming of Age " addresses each of these essential features of the District's development and below is an extract from Chapter 6 of that book which deals with " Climate, Soils and Viticultural Practices in the Canberra District." We are grateful to Brian and Janet for allowing us to reproduce that material here. For further information on " Wines of the Canberra District - Coming of Age ", which is an updated and expanded edition of a book first published in 2002, visit www.mckellarridge.com.au.


 

Chapter 6 - Wines of the Canberra District - Coming of Age

Climatic Conditions

Click for Winery cellar door opening times (Map - Canberra District Wine Industry Assoc)
Click for Winery cellar door opening times (Map - Canberra District Wine Industry Assoc)
The cool climate of the Canberra District is proving to be a key success factor for the grape growers and winemakers of the District.

It is a highly continental climate, with a large difference between the average mean temperatures of the coldest and hottest months (Gladstones 119: 15). Gladstones cites the work of Gadille in Burgundy, where the seasonal characteristics that most clearly distinguish the best-quality vintages are high mid-summer temperatures and high sunshine hours—both key features of the climate of the Canberra District. As Gladstones (op. cit.: 17) notes, however, continental climates are also notoriously variable. The timing of perfect ripening conditions can be precarious in such climates.

While the early pioneers of the 1970s struggled to successfully establish grapes in the Canberra District due to a combination of droughts, pests and spring frosts, current growers have access to improved technology that is making a considerable difference. The use of drip irrigation to assist vine establishment during the dry, hot summers that occur in the District has proven to be essential, and some early frost-prone sites have now been abandoned or the vines grafted to later-budding varieties.

Careful site selection now allows growers to select those sites that have good cold-air drainage to minimise frost problems, and modern spray technology provides effective control of weeds, pests and potential mildew and Botrytis problems. This modern experience contrasts with the somewhat pessimistic views expressed by Dr John Gladstones in his seminal study of the environment and grape growing undertaken in 1992. At that time, he saw little potential in the Canberra District because of the hot summers and frost susceptibility of the region (Gladstones 1992).

Major positives are the high number of sunlight hours, with the mean annual temperature in summer of 20ºC in January, and the long, cool autumns, which produce grapes high in flavour with excellent acid/sugar balance and opportunity for maximum flavour development. Good dryland yields of 5–8 t per hectare are now achievable in mature vines, producing fruit of excellent quality.

The autumn conditions are what provide the opportunity for grape ripening that produces intense flavours and hence special wines. The region usually is subject to ‘cold snaps’ during February or early March, about four to six weeks before harvest. This is thought to cause a buffering effect on the pH levels in the grapes by maintaining malic acid in the grape and, in practical winemaking terms, results in low pH grape juice with good natural acid levels at harvest—a factor strongly preferred by winemakers. The long, cool, generally dry autumns also allow the harvesting of the grapes when flavours are maximised and sugar/acid balance is optimal.

Gladstones (op. cit.: 30) also notes the benefits of coastal sea breezes on grapevine photosynthesis and physiological ripening of grapes. While the Canberra District is more than 200 km from the South Coast of NSW, it often benefits from late-afternoon easterly coastal breezes during summer and autumn, which cool the vine and assist development of the grape.

Temperature Comparisons with Other Wine Regions

Various attempts have been made to “classify” different grape-growing areas using temperature summation techniques in order to identify suitable growing areas.

Dr John Kirk from Clonakilla was instrumental in adapting an early system of this approach, developed by Amerine and Winkler at the University of California in the 1940s, and applying it to the Canberra District (Kirk 1986, 1987).

The temperature summation approach applied by Dr Kirk uses the following formulae. The average daily temperature for each of the growing months (October to April in the southern hemisphere) is summed, subtracting 10ºC (as grapes do not grow below this temperature), multiplying by the days in each month, for each of the seven months to give the temperature summation in (effective) day-degrees.

Dr Kirk then classified the day-degrees categories:

  • 901–1200: Cool

  • 1201–1500: Mild

  • 1501–1800: Warm

  • 1801–2100: Hot

  • 2101–2400: Very Hot.

The Canberra District, under this classification, fits mostly within the Mild category, with average 1400 day-degrees. This is comparable with the Bordeaux region of France, the northern end of the Rhone Valley and the Coonawarra region of South Australia. Important differences emerge in this general picture, however, when differences across the region and altitude effects are accounted for.

Helm and Cambourne (op. cit.) established that some years can be regarded as “cool”, with 1300 cumulative degree-days, and others as “warm”, with greater than 1500 degree-days. In cool years, the climatic conditions typically suit the early season varieties such as chardonnay, pinot noir and sauvignon blanc. Warmer years favour cabernet sauvignon and shiraz, when the additional warmth allows full ripening of the later-maturing grape varieties.

A comparison of cumulative degree-days for the Canberra District with other major grape-producing areas in Europe by Helm and Cambourne revealed:

  • 44.6 per cent of years in the 1301–1500 range of degree-days comparable with the Medoc and Sauterne (Bordeaux) regions of France

  • 32.1 per cent of years over 1500 degree-days, more comparable with the Hermitage (Rhone) region of France

  • 23.2 per cent of years fall in the cooler range of 1000–1200 degree-days, comparable with the Champagne, Chablis and Graves regions of France.

ERIC Analysis

Environmental Research and Information Consortium Proprietary Limited (ERIC), based in Canberra, undertook a detailed analysis of the climate, soils, rainfall and frost hazards in the southern NSW region, under commission from the ACT Government.

Temperature Comparisons

Using the work of Dr John Gladstones, ERIC estimates Effective Heat Degree Days (EHDD) as a measure of the amount of heat required to bring different grape varieties to maturity. EHDD below that required by different varieties will result in unripened fruit (excessively acidic and with little fruit flavour) and EHDD in excess of that required can result in loss of fruit balance, with excessive sugar levels and low acid levels. Good-quality wines require fruit balance and great wines require fruit balance and maximum flavour potential. Experience is showing that the latter occurs in “cool-climate” regions where conditions allow fruit flavours to be maximised and fruit balance to be maintained.

Map 1 shows the EHDD distribution for the southern NSW region, encompassing the Canberra District. The areas to the south of the Canberra Wine District are generally too cold for grape growing, except for small pockets of country in valleys. The area to the west is suitable, ranging from 1000–1300 EHDD in the Tumbarumba region through to 1600 EHDD and above in the west, around Cootamundra and Junee. The Hilltops region has warm–hot grape areas in the 1300–1600 EHDD, depending on elevation. In the east, the area around Goulburn has extensive areas within the cool-climate range.

Map 1
Map 1

 

ERIC has plotted the suitability of the southern NSW region for different grape varieties using the EHDD approach.

EHDD varieties are classified as:

  • Early Season (1150 degree-days required)—includes chardonnay, malbec, pinot noir and sauvignon blanc

  • Early Midseason (1200 degree-days required)—includes cabernet franc, merlot and semillon

  • Late Midseason (1250 degree-days required)—includes cabernet sauvignon, riesling, shiraz and viognier

  • Late Season (1300 degree-days required)—includes grenache, marsanne and mourvedre.

 

Map 2
Map 2

Map 2 presents an analysis of the predicted maturity capability for the southern NSW wine region. In general, the early season varieties are suited to the cooler, higher sites—mostly to the east—and the late-season varieties to the warmer north-west. The central zone that includes the Murrumbateman corridor has many sites suited to mid-season maturity varieties.

Another interesting variable is the altitude choice of the region’s vineyards. These range from 500 to 860 m above sea level, with the highest in the District being Lark Hill near Bungendore. At these altitudes, some restrictions on ripening of later-maturing varieties can occur, whereas at 500–700 m—typical of Murrumbateman, Hall and Lake George vineyards—such restrictions are not usually a constraint.

Rainfall

Annual rainfall for Canberra is 635 mm per annum, with some variation across the Canberra District, generally in the 600–800 mm range. The monthly rainfall is quite evenly spread across the year, with some winter dominance. Evaporation rates are high during the summer months, far exceeding available rainfall.

Rainfall during the winter months, when evaporation levels are low, usually recharges the subsoil, providing a supply for the growing season. The experience of the pioneers—particularly Dr Edgar Riek and Dr John Kirk—was that young vines require supplementary drip irrigation during their establishment, as the summers are hot and dry and droughts are not uncommon.

The autumn weather pattern is usually stable, providing good conditions for final ripening and harvesting. This minimises the chances of bunch rot and mildew, which can be a problem in other climates, particularly Europe. In a wet autumn—as occurred in 2010—rainfall can disrupt harvesting and requires early harvesting to avoid excessive losses due to disease.

Water Requirements

As noted, high levels of evaporation during summer can cause vine stress, and in some years there are droughts that add to this stress. One such year was 2007, and yields were down substantially—about 50 per cent of their normal level. In such years, access to adequate dam and/or bore water is needed if yields are to be maintained and young vines protected from water stress.

Mature vines on sites with deep clay loams do not generally need supplementary watering to produce commercial dryland yields, unless very dry or drought conditions prevail. Growers usually provide dam storage for watering purposes, with many using supplementary bores as well.

Frost Considerations

Another critical factor in site selection is frost damage. The spring months of September to November can be subject to frosts and the grapevine is particularly susceptible to frost during bud burst. Depending on the variety and the location, this can have devastating consequences. Early varieties such as chardonnay, pinot noir and sauvignon blanc, in particular, need to be on frost-protected sites where there is good air drainage if such losses are to be avoided.

Winds

The District is prone to strong southerly winds in spring, which can damage emerging buds, so good wind-protected sites are preferred. Conversely, as noted, cooling easterly winds from the South Coast in the late afternoon in summer and autumn benefit the vines and grape maturation in the District.

Soils

The soils of the region are complex, variable and ancient. The prime groups are ancient granite-based soils, volcanic-based soils and various shale-based sediments (ERIC 2002). The soils are often duplex, with distinct A and B horizons, with a sandy loam surface over a clay loam subsoil.

 

Map 3
Map 3

ERIC mapped eight soil classes and these are shown in Map 3. The most widespread soils are the various sediments, followed by volcanic soils and, third, the granites. They are not highly fertile soils and mostly are quite well suited to grape production.

ERIC also examined the suitability of different soil types for grape growing against the following criteria:

  • good drainage and soil texture

  • good water-holding capacity at depth

  • low to moderate fertility

  • a pH between 6 and 8.

It concluded that the volcanic-based soils, which are widespread throughout the District, are the most suitable because they generally have better drainage and aeration, with a moderately deep sandy loam over a deeper clay loam. Once the vines penetrate into the deeper clay base, they are moderately drought tolerant.

The granite-based soils are less favourable due to a higher clay content in the B Horizon. The sedimentary soils that are widespread are also suitable, but also might have a higher clay content in the deeper soils, which can impede drainage. There are also a few unusual sites—such as those on the edge of Lake George, which are relatively deep, unsorted colluvium sediments, which are also well suited to grape production.

Current Grape Plantings

The last comprehensive survey of grape plantings in the District was undertaken by Leo Burgraff in 2002 for the Viticulture Society of the Southern Tablelands. Since that time there have been some small vineyards withdrawn from production—the result of a combination of very dry seasons and lack of demand for grapes—so the picture will have changed somewhat.

Planting of Grape Varieties in the Canberra District as of 2002

Graph 1
Graph 1

Source: L. Burgraff Survey for Viticulture Society of the Southern Tablelands.

In 2002, the two most-planted varieties were shiraz and cabernet sauvignon. Since that time, the popularity of shiraz has grown and cabernet sauvignon has declined. Some cabernet has since been grafted over to more saleable varieties, some has been removed and the plantings of emerging varieties have also increased. These include small acreages of sangiovese, tempranillo, marsanne, rousanne, graciano and a small plot of grüner vetliner at Lark Hill Biodynamic Vineyard.

It is also important to acknowledge that some Canberra District wineries utilise fruit from Tumbarumba and the Hilltops wine region—chardonnay in particular from the former and shiraz from the latter.

Viticulture Practices

In order to obtain information on current viticultural practices and trends, a postal survey of Canberra District vineyards was initiated, with the support of the Canberra District Viticultural Society and its President, Neil McGregor. The direct link between high-quality grapes and high-quality wine is now well understood in the District and growers are increasingly focused on producing super premium grapes.

Thirty-four responses were obtained from the survey and these were then supplemented with vineyard information available on some winery web sites. The survey, while not complete, is considered broad enough to be generally representative of the District’s practices. Some caution is needed, however, in extrapolating the results to the District as a whole, as some large growers did not reply to the survey.

Age of Vines

The age of vines varies widely across the District, with some of the pioneering vineyards having vines 35–40 years old, but in relatively small acreages. Significant plantings then occurred in the late 1970s and 1980s and many of these vines are now more than 25 years old. Expansion occurred again in the 1990s, with these vines now 12–16 years of age. Since then plantings have been modest, often incorporating new varieties such as sangiovese and tempranillo. A fewer small growers have exited the industry since the last survey—undertaken in 2002—returning forms: “no longer in production.”

Clones

The survey indicated that many different clones of the various grape varieties are being used across the District and some growers were unsure of the exact clones being used. Others regarded the information as “commercial in confidence”. Some of the earlier established vineyards are utilising clones from old South Australian sources and some of these are highly regarded by local winemakers and used in “reserve” wines.

Water Use

All reporting vineyards are using supplementary irrigation to water vines during summer, and in recent years there has been heavy reliance on dams and bores to provide this. Respondents were asked if they had experienced water shortages for supplementary irrigation during the recent run of very dry conditions: 2006–09. Approximately 20 per cent reported some difficulties over the period, with one small vineyard temporarily ceasing production due to lack of water. Also, approximately 25 per cent of growers experienced some diminution of bore flow during this extremely dry period, but none reported complete bore failure. Many small dams also dried up during this period. Most growers, however, were able to manage their vines successfully and excellent-quality fruit was obtained, as reflected in the outstanding wine results.

Current Vineyard Types

Growers were asked to classify their vineyard practices as conventional, organic or biodynamic. Conventional was defined as “routine use of artificial/chemical fertilizers, fungicides or herbicides, as necessary”. Organic was defined as “generally accepted organic practices” and biodynamic was “generally accepted biodynamic practices”. While these definitions are inevitably open to different interpretations, they are generally well understood by growers. Only one vineyard in the District is certified biodynamic—Lark Hill—and 4 per cent considered they were following organic practices, but were not certified organic. The majority—more than 85 per cent—were defined by the growers as conventional, but focusing on minimal chemical input.

Current Viticultural Practices

Growers were asked to report on their viticultural practices such as use of composts, mulches, compost teas, ground cover, shoot thinning and crop-thinning techniques.

The results are reported in the table below.

Viticultural Practices in the Canberra District Vineyards by Reporting Vineyards

Graph 2
Graph 2

Source: Authors’ Survey, November 2010.

Composts and Compost Teas

Nearly 20 per cent of growers are now routinely using composts and mulches in their vineyards to build up soil condition and improve vine health. Another 49 per cent uses them occasionally. In total, nearly 70 per cent make use of composts and mulches to some extent. Compost teas, which are used to build up the microbiological health of vines, are being used routinely by 18 per cent of respondents.

Other Ground Cover Treatments

All growers maintain swards or other ground cover between the rows, managing the sward according to the season. Thirty-eight per cent of growers provide some additional treatments such as inter-row fertilisation of the sward and use of clovers.

Shoot and Crop Thinning

More than 80 per cent of growers are shoot thinning and nearly 90 per cent are crop thinning to manage yields to optimal levels.

Other Practices

Some growers have developed their own viticultural practices to improve soil microbiology and vine health. These include biodynamic practices (Lark Hill Biodynamic Vineyard), as well as techniques such as special trellising (Pankhurst Vineyard), special composting (Yarrh Wines), emphasis on ecological health and optimal canopy management (Kyeema Vineyard), leaf plucking to let light into the canopy (Lerida Estate) and fertigation of vines (Point of View Vineyard).

Future Trends

Twenty per cent of respondents indicated that they are moving their viticultural practices towards more organic methods, but none indicated that they would be applying for organic certification in the near future. One additional small winery is also moving towards biodynamic methods.

Of the respondents, Lerida Estate is working towards a sustainability certification, and Kyeema Vineyard has adopted a model of “ecological health”, in which practices are mainly organic, to encourage a healthy soil biota, and the vines are managed for optimal fruit style for the type of wine. Pankhurst Wines is also adopting a low environmental impact pragmatic approach. Lark Hill, as noted, is a fully certified biodynamic vineyard.

Implications of Projected Climate Change on Canberra District Grapes

Research by the CSIRO and the Australian Bureau of Meteorology (2007) has projected a number of important changes to the climate of Australia over the next few decades as global warming proceeds. These include higher levels of carbon dioxide in the atmosphere, higher average temperatures, lower rainfall in southern Australia, more variable rainfall and more extreme weather events.

Dr Leanne Webb of the University of Melbourne and CSIRO has participated in these studies and was able to provide model projections for climate change in the Canberra District out to 2030 and 2070. The methodology for these projections is outlined in detail in CSIRO and Australian Bureau of Meteorology (2007) and utilises the output from 23 climate models to provide a range of projections: median (best estimate) and range (lower and upper probabilistic ranges). The projections to 2030 are based on a mid-range estimate of greenhouse gas emissions and the 2070 projections utilise a high greenhouse gas emission scenario to provide some upper-range projections. The results of these model projections for the Canberra District (relative to 1990) are presented in the table below.

Projected Climate Change Effects for the Canberra District to 2030 and to 2070 Based on CSIRO and Bureau of Meteorology Modelling

Graph 3
Graph 3

Source: L. Webb, personal communication.

Projections to 2030

The modelling estimates relate to changes in temperature and rainfall relative to 1990 levels. It can be seen that by 2030 the annual average temperature is expected to rise by 0.9ºC, with some differences between seasons: slightly higher in spring and summer and slightly lower in winter. Rainfall is expected to decline by 2.2 per cent, with the largest declines in winter and spring.

Projections to 2070

Without strategies to minimise climate change, the effects by 2070 on temperature and rainfall become more extreme. The projections indicate average temperatures could rise by 3ºC (2.1–4.2ºC) and average rainfall could decline by 7 per cent (–25 per cent to +10.4 per cent). There is considerable uncertainty attached to these longer-term projections, particularly for rainfall changes in the Canberra District, as it could be significantly drier or wetter. This has important implications for vineyard management of diseases and harvesting strategies, so further understanding and research into climate change impacts are clearly desirable.

Possible Impacts on Grape Growing

The most comprehensive analysis to date of possible climate change impacts on grape growing is that undertaken by Webb, Dunn and Barlow (2010).

Broad possible impacts identified are the following.

  • Temperature increases: as the climate warms, grape phenology will be adversely impacted in various ways, including earlier ripening, potentially higher sugar content, hastened acid degradation and altered flavour compounds. Overall grape quality can be adversely impacted.

  • Higher carbon dioxide levels can encourage excessive vegetative vigour and within-canopy shading of wine grapes.

  • Lower rainfall during the year increases the need for irrigation; this could be exacerbated by higher levels of evapo-transpiration. Rainfall events are projected to become more extreme, with projected variability during the growing and ripening seasons.

  • Higher rainfall variability around the time of grape maturity increases the risk of a heavy rainfall event just before harvesting, increasing the risks of disease and berry split—also adversely impacting on quality.

Depending on the severity of the climate change projected, growers will be able to adopt a number of strategies. This could include adapting current viticultural practices to minimise the impact of rising temperatures—such as changing canopy management to increase shading on west-facing vines and increasing the use of inter-row mulching to reduce evaporative losses. Increased attention to preventative disease management in anticipation of heavier rainfall around harvesting is also likely to be required.

If the projected more-severe climate changes occur then the removal of some current varieties might be needed. Replanting with more heat-tolerant varieties in the Canberra District—such as Spanish and Italian varieties—could provide a longer-term solution in the event that global warming intensifies. Fortunately, evidence is sand tempranillo, for example.

The Canberra District experienced particularly warm vintages in 2008, 2009 and 2010, with significant rainfall events post-véraison and around harvesting in 2010. These 2010 events led to losses of some crops due to disease and downgrading of fruit quality in some vineyards, while the dry autumns of the 2008 and 2009 vintages provided excellent-quality fruit across the District.

As at February 2011, the run of “dry” years appears to have finished, with the spring of 2011 vintage proving very challenging for growers because of heavy and persistent rain. This has created severe disease loads in Canberra District vineyards from powdery and downy mildew, in particular. The timing of sprays to prevent and control these diseases is very critical. For a number of growers that were not able to spray on schedule due to very wet ground condition preventing the entry of tractors and spraying equipment, or the failure of equipment at critical times, the results have been devastating with near total crop loss in some cases. Outbreaks of the disease can not only lead to total crop loss, but ongoing spraying is still needed to prevent disease outbreaks in the subsequent vintage. This is very costly.

As noted earlier, managing adverse temperature and rainfall events arising from climate changes will become critical management challenges in the future for both grape growers and winemakers—not only in the Canberra District, but across Australia. This is an important area of ongoing research by the CSIRO, the Australian Wine Research Institute and other key research bodies.

References

CSIRO and Australian Bureau of Meteorology (2007) Climate Change in Australia, CSIRO and the Bureau of Meteorology through the Australian Climate Change Science Program, Melbourne, http:/www.climatechangeinaustralia.com.au/resources.php

Webb, L., G. Dunn and E.W.R. Barlow (2010) “Viticulture”, in C.J. Stoks and S.M. Howden (eds), Adapting Agriculture to Climate Change: Preparing Australian agriculture, forestry and fisheries for the future, CSIRO Publishing, Melbourne.