Contemporary UK viticulture – counterbalancing climate challenges
2016 – a notable vintage
Harvest 2016 will be remembered as an English wine vintage of exceptional quality. The quantity, however, is likely to be low because the wetter than average June meant poor flowering and subsequent high disease pressure, resulting in low yields at many vineyards. The prolonged warm, dry period during the summer and early autumn coincided with veraison (the physiological transition from berry formation to ripening) and provided the perfect conditions for the development of the optimum balance of sugar and acidity that characterises cool climate wines. Another 2016 landmark for UK viticulture was the ninth International Cool Climate Wine Symposium which took place in Brighton at the end of May and brought together experts, including Dr Julien Lecourt (NIAB EMR’s lead researcher in Viticulture who chaired the “Managing climate-based variability” session), from around the world to discuss successful wine production in challenging climates.
UK wines are cool
In just a few decades the UK has evolved from being a small-scale producer of wines which at best could be described as ‘interesting’, to commercial-scale production of world-class still and sparkling wines; joining renowned cool climate wine-producing regions such as Champagne in France, Mosel in Germany and Marlborough in New Zealand. In practical terms a cool climate is one at either high latitude or high altitude where grape ripening is limited by the onset of winter. Similar to the growing day degrees concept of thermal time, ‘Growing season temperature’ (GST) provides a more technical definition and is calculated as the average temperature for each month of the seven month growing season (April to September in the northern hemisphere), divided by seven. Although cool climate wines are considered by many to be those produced in regions with 13 to 15°C GST, as found in the UK vine-growing heartlands of the southern and eastern counties of West and East Sussex, Hampshire, Kent, Surrey, and Essex; locally favourable conditions mean that the UK’s most northerly commercial vineyard is in Yorkshire.
Invention not imitation
Producing grapes at what is essentially the limits of their climatic tolerance means that for sustainable wine production the details of vineyard planning and design, the grape varieties grown and their agronomy, and the winemaking process itself have a profound impact on profit margins. As the New Zealand wine industry has demonstrated with Pinot Noir in Central Otago, excellent wines and their associated financial returns are not produced by merely replicating what has been traditional practice in the old world. With UV levels 40% greater than those of equivalent latitudes in Europe and a 20-25°C diurnal temperature range, new viticulture and wine-making techniques were developed to enable the production of wines with their own distinctive character from vines planted on what had otherwise been dismissed as difficult and highly marginal land. True to the institute’s founding purpose of performing research to sustain and advance the fruit growing industry, the establishment of a research and development vineyard at East Malling means that NIAB EMR is well-placed to support the UK viticulture and wine industry as it seeks to understand and exploit the unique UK terroir (the combined influence of climate and local environmental conditions on a wine’s character). The vineyard will be a focus of the member-funded research commissioned by the East Malling Viticulture Consortium which under the Chairmanship of Geoff Taylor of Campden BRI, has some of the UK’s leading vineyards as founding members: Chapel Down, Nyetimber and Gusbourne Estate.
Applications for membership from forward thinking individuals and companies from all aspects of the UK viticulture sector, who also aspire to the highest production standards, are welcome –contact Julien Lecourt for further details.
Defining and demonstrating excellence
As has been amply demonstrated in many of the New World cool climate wine regions, geological, topographical and climatological equivalence with Champagne are not essential pre-requisites for successful wine production. Indeed, many vineyards in southern England are planted on soils overlying Upper and Lower greensands (sandstones) and sandy limestones. Thus, the free-draining sandy loam to clay loam Malling series soil over sandy limestone on which NIAB EMR established a vineyard in 2015, is representative of other plantings in the region. The East Malling research and demonstration vineyard comprises two thousand grapevines planted in 35 rows on 0.7 ha of level ground. In conjunction with Guillaume Nurseries, rootstocks which differ in their tolerances to soil moisture conditions and fertility, as well as their influence on scion (graft) vigour; and scions representing a range of desirable agronomic and wine-making traits such as phenology, bunch architecture and complex flavour characteristics, have been planted for both scientific and knowledge transfer purposes. Additional partnerships with Valente and Agrii mean that from its earliest days the vineyard has been used to demonstrate different training systems and agronomic practices, respectively, to commercial growers. Four rows of vines replicate a set of seven varieties that the University of Bordeaux has planted in its own vineyard, some 6.5° of latitude further south; with the aim that the effects of climate change can be monitored in the long term.
Climate change contradictions
Although long term climate data indicate that 40% of growing seasons in south east and south central UK between 1989-2013 had an average temperature (~14°C) similar to that of the 1961-1990 Champagne average. Contrary to popular belief, the rapid expansion of UK vineyards in recent years is not entirely due to the effects of climate change. Just as increases in cereal yields can be attributed to the release of Cappelle Desprez in 1946, the wider availability of plant protection chemicals in the 1950s and drainage grants in the 1960s and 1970s; UK viticulture has benefitted from the transfer of knowledge from other New World cool climate wine regions, plus a number of technological and agronomic advancements over the last 20 years. Further advancements will be required to maintain production in the face of the greater year-to-year variability and an increased frequency of extreme weather events. Rising spring temperatures mean that key stages in vine phenology occur a week earlier than they did ten years ago, but this does not necessarily result in yields of better quality or quantity. For example, if frosts in April and May damage young shoots, stimulating the burst of secondary buds, then fewer bunches of poorer quality will be produced because of the effective reduction in growing season length. Similarly, as a wind-pollinated plant, heavy rainfall in June when the vines are flowering, can also be disastrous and in common with many other crops, heavy rain during harvest is also unwelcome.
Tailored solutions for familiar and similar problems
Research leaders from across NIAB EMR’s three research departments: Genetics, Genomics and Breeding, Pest and Pathogen Ecology, and Crop Science and Production Systems, and at NIAB TAG are applying expertise obtained from other perennial crops and arable systems to address vine-specific and cross-sector issues such as the use of innovative training systems and cover crops in the alleys between the rows to improve soil health and crop nutrition, to attract predatory arthropods, and to modify the microclimate. The first indications of the impacts of these aspects of viticulture on the quality of the fruit produced, will be obtained in 2017 when the vines will be allowed to carry berries to maturity. The quality of any wine produced may not be exceptional, but for NIAB EMR it will be a vintage to remember.
Julien Lecourt Tree Physiologist, NIAB EMR
Emma Tilston Soil/Rhizosphere Scientist, NIAB EMR