3.1 Growing Environment & Grape Growing Flashcards
Descibe the location and climate of the Douro region.
The Douro region is located in the north east of Portugal. The total area of the appellation covers 250,000 ha, of which around 43,500 ha are planted and 32,000 ha of these register for DO Porto (the production of Port wines).
It has a warm continental climate, with temperatures easily reaching 40°C in the summer and freezing temperatures not unusual in the winter. Distance from the Atlantic Ocean combined with shelter from the Serra do Marão to the west of the region, mean that the vineyard area is much warmer and drier than the cities of Porto and Vila Nova di Gaia on the coast.
The vineyard area follows the path of the River Douro and is divided into three sub-regions: Baixo Corgo, Cima Corgo and Douro Superior. The most westerly of the regions, the Baixo Corgo, is the coolest and wettest (900mm rainfall per annum), being nearest the cold Atlantic coast. With its cooler climate, the Baixo Corgo tends to produce fruit for many of the inexpensive Ruby and Tawny Ports. The Cima Corgo is warmer and drier (around 700mm rainfall per annum), and most of the well-known producers have vineyards in this region, which are used to produce Age-Indicated Tawny Port and Vintage Ports. By comparison, the Douro Superior, which is furthest from the coast, is the hottest and driest sub region (450mm rainfall per annum) and drought is a frequent issue. The Douro Superior is still relatively sparsely planted, but as it contains some flatter land which allows mechanisation, plantings are increasing.
Although the region is divided very generally into these three areas, the winding River Douro and its tributaries provides a range of microclimates. Vineyard sites vary widely in altitude and aspect meaning that there can be differences in average temperature and sunlight exposure even within a single vineyard.
Describe the soils of Douro.
The stony, shallow soils of the Douro are free-draining and poor in nutrients, which limits vigour. The underlying bedrock is schist, a type of rock that crumbles into layers relatively easily. Due to ancient tectonic movements, the schist in the area splits into vertical layers (rather than the more typical horizontal) and therefore vine roots are able to penetrate deep into the bedrock to find water.
Irrigation is only permitted in exceptional circumstances, for example, periods of drought under which the vine could be in extreme hydric stress. Therefore, what little natural water there is, is the main source of water for the vine. The schist is so important in the viability of grape growing in this region that the boundary of the demarcated Port region mostly follows the outline of the schist. It is very difficult for vines to survive if planted above the impenetrable granite bedrock that is common in the wider area.
The steep slopes of the Douro Valley (many with gradients over 30%) mean that viable vineyard layouts are limited. List the three types of vineyard layouts in the region.
- Socalcos
- Patamares
- Vinha ao Alto
Describe the Socalcos method of vineyard layout.
This is the traditional method.
Socalcos are narrow terraces, supported by walls of dry rock. They allow for planting densities of around 6,000 vines per hectare. This layout is typically not suitable for mechanisation (plus labour is required to maintain the walls), and for this reason socalcos are not usually considered when planting a new vineyard. The socalcos of the Douro are protected by UNESCO, and for that reason cannot be converted to any other layouts. The vines on the socalcos can be planted at lower densities to allow for a small tractor to enter the terraces to reduce so much need for labour.
Describe the Patamares method of vineyard layout.
These are terraces supported by a steep earth ramp, rather than a stone wall. Small tractors are able to run up and down the slopes by the use of tracks that run diagonally up the slope. Patamares are cheaper to implement and maintain than socalcos, however, erosion and the growth of weeds on the ramps can be problematic. Planting densities are relatively low, around 3,000 to 3,500 vines per hectare, as the ramps take up a lot of space.
There are two kinds of patamares:
- Large, wide patamares that support two rows of vines on each terrace. These were the original form of patamares, constructed when the bulldozers that create the terraces were large and bulky. Although growing two rows of vines on each terrace makes efficient use of vineyard land, uneven ripeness can be an issue, with the exterior row of vines gaining more sun exposure.
- Narrow patamares that only support one row of vines. These are a more modern version, carved by newer, smaller bulldozers and often laser technology ensuring precise construction. These patamares are often tilted very slightly towards the slope and also from one side of the terrace to the other, both of which improve water absorption and drainage and reduce erosion. With only one row of vines per terrace, uneven ripeness is less of a problem.
Describe the Vinha ao Alto method of vineyard terracing.
In this layout option, the vines are planted in vertical rows up the slopes. It is the least expensive option to plant and maintain and allows for relatively high-density planting (around 5,000 vines per hectare), and hence efficient use of land. However, above a 40% incline, mechanisation cannot be used, and therefore patamares are more likely to be used in these cases. Water run-off and erosion can also be significant problems. Use of this vineyard layout is currently relatively limited.
How are vines usually trained in Port?
Vines are cordon-trained and spur-pruned or head-trained and cane-pruned, and VSP trellised, to promote even sun exposure and ripening, and allow for mechanisation where viable. Summer pruning, such as leaf removal, may be used to ensure sun exposure throughout the growing season, especially for late-ripening varieties.
What rootstocks are widely used in Port?
Rootstocks that are tolerant of drought (generally 110R and 1103P both of which are hybrids of V. rupestris and V. berlandieri) are widely used.
The maximum yield permitted for Port wine production is 55hl/ha, but due to limited water availability, and, in some years, the hazards and diseases described below, yields are more likely to be around ___hl/ha.
The maximum yield permitted for Port wine production is 55hl/ha, but due to limited water availability, and, in some years, the hazards and diseases described below, yields are more likely to be around 30hl/ha.
Describe the hazards and pests in the Douro viticultural area.
Viticultural hazards can include late spring frosts in the highest altitude vineyards and in some years cool, wet weather from the west during the early summer, which disrupts flowering and fruit set. Downy mildew and botrytis bunch rot can be issues, especially in the wetter Baixo Corgo. These are combatted by canopy management techniques and spraying with fungicides.
What can be done to imrpove the soil in Douro’s vineyards?
Fertilisers may be used as necessary to improve the poor nutrient status of the soil. Herbicides may be required to control weeds that grow on the slopes of the patamares, which can compete with the vines for water and nutrients.
However, if there is enough space a small mower may be used. Cover crops may be grown on vinha ao alto slopes to prevent erosion, improve soil structure and nutrition, and reduce the presence of weeds. A number of the largest growers and producers are increasingly farming using sustainable or organic techniques where and when it is possible to do so.
True or false?
Harvesting in Douro is mostly done by machine.
False.
Harvesting is carried out by hand; much of the vineyard topography is not suitable for machine harvesters. An ageing regional population (and continuing depopulation) is fast catching up with growers who each year face increasing difficulty in finding enough people to pick.
Symington Family Estates, itself the largest single grower in the region, has been developing (since 2015) a suitable machine harvester to ensure that, if labour sourcing becomes too difficult, they will still be able to harvest their fruit. The harvest tends to start in the Douro Superior and end in the Baixo Corgo. The various microclimates within the valley, the use of different grapes and the prevalence of hand-harvesting (relatively slow) means that harvest can be spread over several weeks.
True or false?
There are over 100 grape varieties permitted for the production of Port.
True.
Since the 1980s five prescribed varieties have been the focus of replanting efforts and clonal research in Douro. What are they?
Touriga Franca, Tinta Roriz, Tinta Barroca, Touriga Nacional and Tinto Cão.
However, many small vineyard owners continue to plant in the ways that have been carried out for centuries, and therefore the many of vineyards in the Douro are planted with a field blend. Furthermore, a number of producers are looking at varieties outside the prescribed five, particularly if they can make valuable contributions to the blend such as colour and acidity, and research is focused on maintaining the diversity of indigenous plantings and investigating their future potential, with the effects of climate change particularly in mind.
Describe 5 or more red grapes used for the production of Port.
- Touriga Franca – A late ripening variety, making it suitable for growing in the warmest sites (low altitude, south-facing). It has tight bunches of thick-skinned grapes, which makes it relatively resistant to fungal diseases. However, it can be vigorous and this needs to be managed, usually by summer pruning. It contributes colour, tannin and acidity as well as juicy red and black fruit flavours and floral aromas to a blend. For these reasons it is popular with growers and Port producers and is by far the most grown variety.
- Tinta Roriz – (Tempranillo in Spain and Aragonez elsewhere in Portugal). An early ripening variety, that is best grown in relatively cool sites as otherwise it can suffer from water stress. It can lend body and deep colour to the blend. It is capable of producing high yields, but these need to be limited otherwise the wines can lack concentration.
- Tinta Barroca – An early ripening variety that is best planted coolest sites (high altitude or north-facing slopes, generally in the Baixo Corgo and Cima Corgo) otherwise it is prone to heat damage and grape shrivelling. It is not as floral as some of the other grapes, with flavours that tend to be more earthy. Unless planted in the coolest sites, it can lack acidity, and its colour also tends to fade more quickly than wines from Touriga Nacional and Touriga Franca. It is capable of producing high yields of grapes.
- Touriga Nacional – A mid-ripening variety with thick-skinned grapes, producing wines with deep colour intensity and high levels of tannins. It retains acidity well and displays concentrated flavours of black fruit and floral aromas. Its wines are said to have long ageing potential and hence it is often a component of the premium, long-matured wines. It can suffer from excess vegetative vigour, which needs to be managed through summer pruning, and is susceptible to coulure, which can lower its yields substantially and cause vine imbalance.
- Tinta Amarela – (Trincadeira in other parts of Portugal) Prone to fungal diseases due to its tight bunches of grapes. Produces full-bodied wines with concentrated black fruits and spicy notes, that are approachable in youth, but are also capable of ageing.
- Tinto Cão – A low yielding variety that produces small thick-skinned grapes that are resistant to fungal disease. It ripens late and is very tolerant of heat. It produces concentrated wines with high acidity and the capacity to age well.
- Sousão – A thick skinned variety becoming increasingly popular for its deep intensity of colour and ability to retain high levels of acidity.
