The project has been launched in conjunction with research institutions in Chile and Germany.

Mario Pablo Silva planting carmenère

Casa Silva already has a reputation for making fine quality carmenère wines and the company is already making Chile’s star grape variety, carmenère, its own. Their investments appear to bear fruit, as Mario Pablo Silva, managing director of Viña Casa Silva explained: “we think carmenère is a very important grape for Chile, and we trust carmenère will produce differentiation for Chile [from other countries].  Casa Silva sells as much carmenère as cabernet sauvignon, and we sell more carmenère than cabernet sauvignon of our top wines.”

The research aims including looking at the fine balance of herbaceous green pepper notes, which in certain small proportions are a complexing factor, but more than this turn into a marmite issue. Additionally, carmenère is susceptible to unpredictable fruit set, so finding clones that are reliable for this aspect will be high on the agenda.

Pyrazines

Along with the herby green pepper notes are other pyrazines such as green asparagus, green beans and peas flavours.  Too much of these is considered a fault, and not enough of them can make the wine a little one-dimensional.  These aromas are called pyrazines, and existing carmenere clones show a near four-fold variation in amounts, from 40 to 150 nanograms/litre (ng). These are infinitessimally tiny amounts, but which are easily detectable on the palate.

Carmenère

Professor Yerko Moreno, director of grape and wine research at the University of Talca,  is one of the collaborators in the research project. He said “We would like around 60-70ng. We don’t want to lose the peppery characters, otherwise it wouldn’t be carmenère.”

But what creates the pyrazines, and how to manage the vineyard to optimise the quantity? Moreno said: “By removing crop we increased the amount of pyrazine in the remaining crop.  The pyrazine produced in the leaves concentrates in the fewer bunches that remain.

“High water stress got rid of pyrazines, but it got rid of everything else as well. We don’t think stressed vines produce good quality, we think happy vines produce good quality.”

Moreno went on “we can harvest carmenère earlier if we treat it well in the vineyard. If we stress the canopy, it won’t get rid of the green characters. But by keeping the canopy alive late in the season, we ended by harvesting earlier.” Managing director of Casa Silva, Mario Pablo Silva, added “we like the greenness of the carmenère. Winemaker friends’ are surprised to see us harvesting Los Lingues in April and they are thinking to harvest in May.  If you taste a really good carmenère you taste freshness and greenness.” But not a lot of greenness. Though the earlier harvest helps to retain a little more natural acidity for the freshness.

Variable fruit set

Another of the issues with carmenère is a variable fruit set, which directly affects the yield and therefore profitability of the harvest. Variable fruit set results in both ripe and unripe berries on one grape bunch.  Moreno said: “doing pollen analysis we found up to 30% of carmenère pollen grains has faults.”

Clones

One of the ways to gain more control over these issues is to breed carmenère for the desired traits – better fruit set, limited pyrazines. 

Los Lingues vineyard

Specific clones of most grape varieties exist for various traits, such as small berries, or drought resistance, or stronger wood etc.  But at the moment there are no official clones available of carmenère. Carmenère is just carmenère, with all vineyards (not just Casa Silva) being a massale (vineyard) selection.

There are, however, some candidate clones. Moreno said it takes 7 to 8 years of information gathering and validation before a clone can be registered and authorised, adding “at the moment we have 42 candidates at the University”. 

This will open up the whole clone versus vineyard selection debate on carmenère, as Pablo Silva said: “the best wines may still be produced from massale selection; we don’t know.”

Over the next few years they’ll be working at the genetic level, studying the expression of the gene producing pyrazines, as well as researching the faulty pollen grains to improve fertility. And if they solve the various issues, Moreno said: “we will have a super-carmenère, which should give better wines.”  You can’t fault that.  

No results are expected for two or three years.

Los Lingues vineyard

The Casa Silva study came about because the family-owned and run company wanted to understand why they had the same grape variety in the same climate but they were getting quite different wines.  They wanted to explain this variability so the knowledge could be used to grow grapes better matched to the style and quality of wines they wanted to make. 

And they’ve discovered that even very small distances in the vineyard can produce different results in the wine, which is making them re-evaluate what they plant and how they manage the vineyard on a micro-scale.

How it happened

The research project was started in 2005, by Casa Silva’s technical director and chief winemaker Mario Geisse, in conjunction with Professor Yerko Moreno of the University of Talca, where he is the director of grape and wine research, specialising in viticultural issues including clonal selection. 

They started looking at small ‘terroir units’ of 0.1 to 0.5 hectare with an aim to identify the pre-requisites for growing high quality carmenère in Colchagua.

Prof Moreno in a soil pit

They investigated crop load (the weight of grapes per vine), vegetative vigour (foliage), as well as the soils, which have all been brought down from the Andes over the last 300,000 years, and contain more or less rock, depending on location.  Professor Moreno said the team identified “small terroir units for carmenère, cabernet sauvignon, viognier, syrah, petit verdot, considering climatic conditions, topography, soil composition and origin, vine rootstock, variety and clone, and viticultural managment.”  He said they dug hundreds of soil profiles, describing them for chemical composition, water holding capacity, rooting capacity, which allowed them to separate areas into different units, broadly along the lines of sand, limestone and clay.

They measured growth parameters of the vine, including the vegetative canopy and yield, and related this to bunch shade/exposure. Moreno said: “If you have a grape cluster that is too exposed under our conditions, you can cook the berries. It’s completely different from areas of cooler climate. It can reach up to 45°C in our valley.” What they found was that sunny berries had lower colour, harder and drier tannins. 

Then they did lots of small batch winemaking and carefully analysed the resulting wines, creating a virtual warehouse of vineyard and winery data.  Once they started to sort out some of the effects, Moreno said “One of the most important for me was the water behaviour of plants. Cultivars have different responses to stress – syrah copes with more stress than cabernet sauvignon. And vines of the same cultivar behave differently in different sites, and within one season.”  He added “cabernet sauvignon with severe water stress produced more astringency in the wines, the tannins were too harsh.  And if there was no water stress, we tended to have similar problem – the tannins were too harsh.” 

But on carmenère the results were different. With no water stress there were “green characters.  We got some dry tannins with increased water stress, though not as much as cabernet sauvignon.” He explained “the best expression of carmenère was achieved where the plant had to explore greater soil volume to get its water supply, at least one metre deep.”

The results of this research are enabling Casa Silva to replant areas of vines. Moreno said: “I would change the way the vineyards are planting, not the direction of rows. This project is aiming to produce high quality wines, the variabilities are subtle.  New plantings are being done considering the soil.” Combine this with tweaking vineyard management to realise more potential from their grapes should enable Casa Silva, Geisse said, “to get the best possible quality wines” from each plot.

The research also revealed quite marked genetic variability in the carmenère vines, so Casa Silva recently embarked on new research into carmenère clones to identify those that produce better quality fruit for high class winemaking.

Majestic £8.69 per bottle standard.
Between Oct 30, 2009 and Feb 1, 2010, buy 2, save 20% … £6.95

Costero Riesling 2009

Viña Leyda is producing some of the most exciting wines coming out of Chile at the moment. This riesling is no exception, and on promo it provides really tasty value for money.

The vineyards are around 15km from the Pacific Ocean, which provides chilly winds to cool down the growing fruit. This helps retain both acidity and aromatics.

It’s an easy and gentle riesling, so if you think you don’t like riesling, I reckon this one is fab. enough to suggest you have another look.

Intense fresh lime flavours attack your palate in a zesty but not tingling manner, and give way to a gentle, smooth palate with a mouthfilling volume of lime and citrus fruit.  Excellent balance accentuates the moreish, pure fruit flavours. The wine is focused.  It’s not complex, but it is layered with unadulterated primary fruits, having been made entirely in stainless steel.

Llamas in Patagonia

Viticultural Chile is moving at a pace that would pride a troop of triffids. In a country where more than 40% of the vineyard area is less than 10 years old, new valleys, outside the preserve of the Central Valley, are being explored in the quest for cooler climate Chile.

But ‘normal’ climatic rules no longer apply. Chile may be that long, skinny country 4,200km from north to south and only 100km west to east, but Diego Benavente, winemaker at Matetic Vineyards, in San Antonio valley said “people say Chile is wider than it is long because the climate changes more dramatically east to west than it does north to south.” Marcelo Papa, Concha y Toro’s head winemaker drummed home the point: “In Chile 10 to 15km east to west can make the equivalent change of 400km north to south.”

So while Elqui to Bio-Bio is more than 1,000 km distant, it’s time to forget the north-south divide, and rethink Chile in terms of east and west, as well as low and high altitude.   

Fogs and ocean breezes

In many parts of the world, MJTs (mean January (southern hemisphere)/July (northern) temperatures) and degree days remain a useful starting block from which modifications and refinements can be made to identify climate zones. But the indefatigable Marcelo Retamal, climate and soil expert as well as De Martino’s chief winemaker, said “For me it’s most important to recognise the warm areas in the world using the average of the maximum temperature.” The mean temperature works, he said, but the high diurnal temperature variation in all parts of Chile is important.

The Humboldt current drives part of this, coming up from the Antarctic, bringing chilly winds.  Ocean influence is crucial and is often a combination of fog, near the coast, and ocean breezes, which can reach quite far inland, where transverse valley topography allows.  

Much of San Antonio Valley, on the west side of the coastal ranges, is open to direct ocean influences. Viviana Navarrete, the winemaker at Viña Leyda, 13km from the coast, said they have “mist and fog the whole year which stays till noon. Then breezes push the clouds away and we get sun in the afternoon, which allows us to ripen with freshness.”  

Freshness is an important issue for these producers. Francisco Ponce, winemaker at Viña Garcés Silva, which produces the Amayna brand, said they feel the “cool climate in the acidity of grapes. Here we don’t lose the acidity, it’s still at a good level.”

San Antonio is colder, windier and foggier than Casablanca. As well as general coolness, we return to the diurnals. Benavente said: “the difference between day and night is sometimes more than 20°C. Polyphenols evolve slower with high diurnals, we have to wait for them to ripen. There’s not much metabolism at night.” Even though viticulture is less than 10 years’ old, the valley’s suitability for sauvignon blanc, chardonnay, pinot noir and some interesting early examples of cooler climate syrah have become evident.

Casablanca Valley

At just over 20 years old, the grand old dame of Casablanca, also on the ocean side of the coastal ranges, is these days regarded as a rather large and diverse region, erring towards 50km across, which is in fact notably warmer at its east end than its west end, given the latter’s greater proximity to those cold Humboldt breezes. Additionally the fogs, which provide temporary respite from the sun, do not reach the east end of the valley, and a temperature gradient of up to 4°C has been observed between the west and east of Casablanca, with the east end harvesting up to three weeks before the west end.

Luminosity

One thing the fog does is to reduce the level of luminosity. Benavente, in foggy San Antonio, said: “there’s less luminosity here. We’ve planted mostly north facing slopes to get more sun. In the ripening season say we get 3 to 4 foggy days a week.” The downside, he added, was that “too strong an ocean influence is detrimental to flowering and yields.”

Luminosity is all about the amount and intensity of light, independent of temperature. It’s great for photosynthesis. According to self-declared non-expert on the subject, Aurelio Montes, chairman, founding partner and winemaker of Viña Montes, “most grape varieties would love some luminosity for colour, phenols and tannins. It’s found more in high level altitude, where humidity is low.”

He added “luminosity is not temperature – mountains can be freezing, but with high luminosity.” (sunburn on the ski-slopes?). Retamal addresses this apparent paradox of sunburnt grapes and cooler climate:  “UV is part of luminosity. Limarí is cool climate in terms of temperature, but we have light, and the grape skins can get sunburn. We’re changing rows to east-west.  If rows are north-south, both sides of bunches burn.  If they’re east-west, the idea is the sun crosses over the row. We need to cover fruit with leaves.”  At De Martino’s Quebrada Estate, which is 24km from the ocean, he said “this year we decided not to use wires with VSP [vertical shoot positioning]. We let the shoots fall down [for shade], and we had no burn problem.  We picked three weeks later, the wine had 13.6% alcohol, the acidity was very good, the pH was good, the wine is outstanding.”

The Limarí valley is making a name for both chardonnay and syrah. Concha y Toro’s Papa explained their Maycas del Limarí  project: “Limarí is affected by the ocean. The coastal ranges do not exist [so plenty of wind]. But Limarí is quite extensive, there are some warm parts. In the area we’re growing, the maximum average January temperature is 25°C, the minimum average 12°C.”  He said this roughly compares to Puligny Montrachet, but the length of time over which the peak of temperature extends is longer in Limarí, which is important. Chile’s high alcohols are partly explained where the average maximum extends for several months. Compare this to Bordeaux for example, where it extends for just one month.

Parked just outside the winery

Further north still, despite a little closer proximity to the equator, Elqui Valley still has cool bits. De Martino own Chile’s highest vineyard at 2,000m ASL in Elqui, a region probably more famous for having some of the best quality light on the planet, to which several observatories attest. They’re using a new-to-winemaking training system, the parrón Elquino, a variant of the pergola, where a single long branch, angled at something approaching 45°, is trained at height to provide shade against sunburn. The system was originally created for local people who produce grapes for Pisco, and who know a thing or two about grape growing in the region.

Andean altitude

Moving over to eastern influences, the Andes also play their part in moderating temperature, in the foothills, offering a slightly cooler spot in an otherwise warmer area. As such it’s better suited to later ripening varieties, so while cabernet sauvignon is frozen out of the ocean coast, it finds succour in the Andean foothills. Cabernet sauvignon ripens late. It needs warmth to avoid herbal notes, so cool for cabs is more likely to be a cooler spot in a warmer clime. Andes and altitude rather than ocean and aeolian influences.

On the subject of cool climate cab, Montes said: “it doesn’t work in Casablanca, Leyda, and Limarí. There’s too much minty, eucalyptus and pyrazine flavours. But cool climate cabernet sauvignon is found in the Upper Maipo and foothills of Colchagua at 500 to 650m altitude. Over 700m is too cold. ”

Pérez Cruz takes advantage of just such a foothill spot, being 50km south east of Santiago in Maipo Alto, at altitudes of 480 to 520m. Their winemaker, Germán Lyon said: “it’s not a cool area, it’s warmer than Bordeaux, but it’s not too warm. The south east spot of Maipo is cooler than Colchagua for example. The vineyards are the first to be cooled by the Andes at night, and the last to be warmed during the day by ocean breezes. The day-night temperature variation is 18-20°C.” For late ripeners such as cabernet sauvignon, the trajectory continues to be finding cooler spots in the general warmth.

Antarctic latitude

Way down south towards the cooling Antarctic, Bio Bio valley is recently oft-touted for aromatic grape varieties such as riesling, gewürztraminer, even pinot noir. But disease pressure becomes more of an issue.  Rainfall increases as you go further south, more than 1,000mm in the Bio Bio to over 2,000mm at Puente Montt, south of Malleco Valley (which isn’t as far south as Marlborough in New Zealand).

But there’s that east-west effect again. Retamal explains: “It is the proximity to the ocean that will determine whether the climate is cool or not.  If you are close to the ocean or next to the canyon of a river where you can sometimes experience cooler breezes, you will be in a ‘cool climate’.  However, if you are close to Los Angeles, the main town in the region, the likelihood is that you will be in a warmer climate, since this middle area of Bio Bio generally records peak summer temperatures that push 33°C – warmer than Santiago.”

So, with apologies to Germany: thought you knew Chile – think again.