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New World Wine Maker Blog - winemaking

Let’s Talk About Appassimento Wines

What is ‘Appassimento?’

Appassimento is a wine processing technique in which harvested grapes go through a drying process prior to fermentation. This process is used traditionally in Italian wine regions to make the popular Amarone, Recioto, Valpolicella Ripasso, and Sforzato wines.

Appassimento influences the flavor and concentrates sugars in dried grapes. This results in flavor and mouthfeel alterations in the wines that use grapes dried by appassimento methods. As the sugar concentrates, through water evaporation, wines produced from dried grapes may result in higher alcohols. Flavors becomes more rich and bold, adding complexity to still wines.


This appassimento-style wine is produced at Barboursville Vineyards in Virginia. Photo by: Denise M. Gardner


Why is “Appassimento” of Interest to U.S. Wine Regions?

In the last few years, I have noticed appassimento techniques implemented at a number of wineries across the U.S. and Canada.

While many may assume appassimento grapes could be used for dessert wine production, this technique can also be applied to dry wines. Like hanging grapes out on the vines during the coldest winter months, appassimento is a concentration technique.

In the East, we often discuss primarily two ways of improving still, red, dry wines:

  1. Enhancing extraction of grape constituents during production, and
  2. Improving the concentration of desired characteristics like flavors, aromas, sugar, tannins, and polysaccharides (long-chain sugar compounds that improve viscosity and softness of a wine).

Winemakers often use methods like cold soaking or extended maceration to enhance extraction of grape constituents. Additionally, using tools like rotary fermenters can help improve extraction by extending juice/wine contact time with grape skins.

In contrast, improving concentration requires different winemaking strategies. Extended hang time, to concentrate sugars and ripen flavors could be viewed as a concentration technique. The presence of Noble Rot concentrates sugars and flavors. The use of reverse osmosis, especially when applied to juice, is a concentration technique that removes water. Flash thermovinification, in some respects, is a concentration technique that can alter flavor and mouthfeel characteristics of wine. All of these methods help minimize the influence of unripe characteristics (i.e., usually green aromas). In some cases, sugar levels may be concentrated as well.

The drying process associated with appassimento evaporates water from the grape berries, concentrating sugars. Additionally, the drying alters primary flavors that will be passed onto the wine. Some of these flavors may appear more “ripe” in their description. Common sensory descriptors for appassimento grapes include: prunes, raisins, dark fruit, black fruit, honey, dried violets, and dried fruit.

When applied appropriately, such grapes can transform a still red wine with fresh red fruit characters into a bolder, richer wine.

How Can I Integrate Appassimento into My Winery?

The use of appassimento requires careful planning, specifically for where and how grapes will be dried. Traditionally, in Italy, drying houses can be complex. Environmental parameters like temperature and humidity are controlled. Pest control and spoilage are important factors that are routinely monitored.

Recent research in Canada, through the Cool Climate Oenology and Viticulture Institute (CCOVI), has looked at alternative drying methods including use of:

  • On-vine hang time,
  • Barn drying,
  • Drying chambers,
  • Greenhouses, and
  • Kilns.

Other industry members in Virgina have used old toacco barns for drying grapes.


If you have an interest in appassimento wines, we’ll be discussing this topic at the 2018 Wine and Bev X Conference in Washington D.C. (February 21st). [Use the promotion code, DGWINE, to receive 50% off your registration.] Attendees will be fortunate to hear from Luca Paschina, winemaker at Barboursville Vineyards (Virginia) who has many years of experience been making wine from appassimento grapes. For those that have not previously been to the winery, there is an appassimento drying house on site, emulating the traditional Italian process. The Barboursville Vineyards Paxxito (Malvaxia) was one of the first U.S.-produced appassimento-styled wines I tasted. Using Moscat Ottonel and Vidal Blanc grape varieties, it is truly an unique wine with a lot to offer. I have always enjoyed its pairing with dessert at the Barboursville Vineyards on-site restaurant, Palladio.

In contrast, winemaker Sean Comninos from William Heritage Winery (New Jersey) will discuss production of his first red appassimento-style wines. Sean will bring insight and contrast to Luca’s rich experience integrating appassimento techniques into the winery. I look forward to delving into all that Sean learned during the first year of his wine’s production.

If you have followed up with previous blog posts, you know that Dr. Debra Inglis and Michael Jones will also join this session. Both of them bring a plethora of knowledge and technical details related to managing wine quality during appassimento and throughout production of the wine.

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South African success at IWSC

The international Wine and  Spirit Competition was established in 1969 by a German wine Chemist, Anton Massel, who was resident in Surrey,  England. Known first as “Club Oenologique” and held it’s prize giving at the Bristol International Wine Show. Before TV South Africans got to know about the show and the competition when the Bergkelder did so well and Peter Stuyvesant produced  a magnificent , wide screen cinema advert that ran for more than a year ! Now the IWSC is in it’s 46th year it is recognised as the World’s premier wine and spirit competition. Currently receives entries from about 90 countries around the world and for many years the annual awards banquet is held in the magnificence of Guildhall in London. With all the pomp and ceremony that only the Brits can do.

South Africa has always done well and it’s wines and spirits have a long and proud record of achievement.  When the Trophy for the best overall wine producer was first introduced in 1985   Gunter Brozel of Nederburg was the first ever winner. The Cape Wine Academy very early on presented a trophy for the best South African performer. When they withdrew the trophy for the best South African wine producer it was taken over by Dave Hughes and it is still the trophy for the top performing South African winery. The trophy for the best overall Distiller is a more recent innovation and it first  came to South Africa when Distell won it in 2007.

2015 is the first time South Africa have succeeded with both.  Turned out to be very popular winners with the 500 people erupting with the announcement first of the Kanonkop success and then that of Distell. No other Country has ever matched the achievement and it would be difficult to do as there are few countries that excel at both wine and spirit production. France, Italy, Spain and Portugal could, but have never come close. The next trick would be for one company to win both !! Distell and KWV are probably the only companies in the world that could achieve this. Now there is a challenge if ever there was one !

Only three wineries have ever won the Winemaker of the year three times. Wolf Blass and Mc Guigan both of Australia and now Kanonkop of South Africa.

This year the success of the Distiller and Winemaker awards has somewhat overshadowed the other South African successes. As might be expected the best Pinotage worldwide went to Kanonkop 2012 with other entries from Israel, new Zealand and California. The best Chenin Blanc went Forrester Meinert with their FMC 2013. The best Riesling was a complete turn up for the books with Paul Cluver Ferricrete 2014. The best Chardonnay went to Jordan with their 2013 Nine Yards. The third time Jordan has won this which draws about the biggest entry world wide. South Africa has agreat record with Chardonnay with Rustenberg winning the trophy two years in a row, 2008 and 2009. I would expect South Africa to win the Pinotage but there was a year when a wine from a Southern Hemisphere country that was well admired by the judges until I said “it might be a great wine but it is not pinotage!”. On inspection the label stated “Pinotage” but it was a blend of mainly Shiraz (Known by some in that country as “Hermitage”) and some Pinot Noir ! South Africa has also done particularly well with blended reds. However, the Cape has absolutely dominated the Dry Chenin Blanc category. Introduced in 2006 and sponsored by Spier Wines. The first winner  was the 2004 Maverick Chenin Blanc. For lack of a sponsor there was no award in 2010 but every other year it has been won by South Africa. Twice by Stellenrust, 2011 and 2012. The FMC 2007 win in 2009 and the 2013 FMC took the honours this year  (2015).


South Africa has dominated the Brandy awards in recent years having received  the top trophy for Best Brandy Worldwide 10 out of 12 years. Van Ryns 12 year old is the master in this respect having been judged the best  four times over past twelve years. Van ryn’s 20 year old has won twice while Joseph Barry 10 year old has been successful once in 2009. The KWV have won three times with 12 year old in 2014 and previously their 15 year old in 2007 and the Laborie Alambic in 2010.

The IWSC has a different “President” each year and in this department South Africa has not done well with Dr Anton Rupert being our only ever representative in 1996.

The International Wine and Spirit Competition is a great and consistent barometer of the quality of South African wines and spirits. South Africa really punches above it’s weight when see our success measured against the number of entries from other countries. With wine, France leads the entries with some 15 % each year. Followed by Italy with 14%,  Australia 12 %, South Africa 10%, New Zealand and Chile with 6% each. Portugal 5%, Argentine 4% and the USA 2%. When it comes to spirits Scotland leads with 24% followed by France 15% . USA 3% and South Africa 2 %

Hopefully the above gives a good perspective of just how well South Africa has done and is doing at the International Wine and Spirit Competition.

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From the Winemaker’s Bookshelf

Venerable Viticulture

There are a few books that just never seem to go away.   Even though I may have read them twenty years ago or more, these are the books that I open first when I have a fundamental question.   The first of these is Philip Wagner’s  “A Wine-Grower’s Guide”.  A new edition of this book was published by the Wine Appreciation Guild, ISBN 093266492X in 1996.

I first encountered Phillip Wagner over 30 years ago at the annual meeting of the American Society of Enology and Viticulture.  Phillip was delivering his thank you speech after receiving an award.  He spoke of recent research to select new hybrid grape varieties that were mildew resistant and winter hardy, and the strategies that European breeders had to use for selection.  He then went on to say “I grow grapes inMaryland.   We have cold winters, hot, humid summers, and an annual hurricane season.   If a grape will survive inMaryland, it will grow almost anywhere”.   This down to earth, hands on, practical approach to viticulture is the factor that made his books so popular.  The first edition was published in 1945.  This is another of the books that I’ve replaced several times through book loans that never returned, and the 1980 edition is my present copy.  A 1996 edition is the most recent.  Phillip died in 1996 at the age of 92.

I specifically chose the Wagner book for this review because it has a focus on the cultivation of hybrid grapes, those which have been selected from crosses with non vinifera parents.   Even though present market demand is for wines from vinifera wines such as Chardonnay and Merlot, there are many who believe that the future must lie with better hybrid selections that can be grown with no sprays and higher yields.  There is no question that with the present hybrids the vineyard and winemaking practices are different from those for vinifera.   Wagner shared his insight.

The second book is Winkler’s  “General Viticulture”; Universityof California Press.  The 2002 edition has authors Winkler, Cook, Kliewer, and Lider, ISBN 0520025911   This is by far the most widely used North American viticulture text.   In contrast to Wagner, the focus of this book is on vinifera grapes and California.   My copy, which has only been replaced once, is the fourth printing, 1973.  It has a wealth of information, ranging from a history of viticulture, the species of the genus Vitis, climate, soils, grape physiology, propagation, diseases, and a host of other topics.

Winkler also had a way of finding practical solutions, and the text is filled with guidance for the performance of day to day vineyard management.   Those in the grape industry actually have a measurement called a “Winkler’s Thumb”.    This is the distance that a bud on a spur must exceed from the head or cordon in order to be counted as a fruiting bud.   If the distance is less than a thumb width, the bud may not be fruitful.

Each of these texts offers good guidance for the novice grape grower but in addition, has enough detail to be a useful guide for the experienced and practising grower.   Even though I may have read a text in its entirety, I find that each time I return, I find material that seems new.   I never quite pick it all up the first time through or I forget the details when it is out of my mind.  A good text is always an adventure of discovery when you’re trying to do your job just a little bit better this year than you did last year.

This article first appeared in the British Columbia Fruit Grower.

Gary Strachan is an expert consultant and planner for the grape and wine industry. He can be reached and is also listed on LinkedIn.

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2014 Bloom Progress

May 15th and we are at the end of a string of near-100° days — a pattern that has set in for the time being here in the North Bay: 3-4 hot days followed by 3-4 cooler, “normal” days. The picture above illustrates the start of bloom in the Syrah at our Estate vineyard. I also noticed a few flowers in the Roussanne and the Cabernet. No flowers yet in the Tannat, while the Mourvèdre and the Counoise look to be weeks away yet.

All the cane-pruned blocks of Pinot are in full bloom, though I don’t see any set and beginning of berry sizing in any of them. I speculate that the heat is holding back development a little. About half of the clusters in the cordon-pruned Pinot are in flower, compared to none five days ago. The big surprise for me was to see that about half of the clusters in the Grenache are flowering:

As my daughter would say, comically and with a full understanding of how silly it sounds when others say it (thankfully!) “that’s totes cray-cray!

John Kelly is the owner and winemaker of Westwood Wines, Sonoma California. This blog was originally published on his blog: “notes from the winemaker” .

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Hang loose, Dude

In our northern latitudes, things change from year to year and what you got last year may not be what you get this year.   There are a few tricks to getting a heads up to minimize surprises on the crush pad.

First of all, get to know the vineyard where you source your grapes.   What is the soil profile like?   Does it have good enough drainage that growth can be controlled by appropriate watering.    Is the vine spacing wide enough to allow balanced growth without multiple hedgings and toppings throughout the summer?   Is the air drainage good enough that the season won’t end prematurely with an early frost?    One last and very difficult question:  Is the season length of the grape variety matched to the frost free growing days and the typical growing degree days of the site?   This is the foundation of a vineyard that will give you more consistent composition in spite of changes in heat units and rainfall from year to year. 

There are two potential problems if the grape variety doesn’t match the vineyard.    If the grape is a long season variety such as Riesling or one of the Cabernets on a cooler site, then you may have to cope with immature grapes in all but exceptional years.   Watch for cane darkening, taste the berries, chew up the seeds and skin to assess ripeness.   Don’t depend on lab tests alone to tell you when to pick.    You could end up having to cope with green flavours, pale colour, and thin body.   The quick fix for a red wine is to not make a red wine.    Make a rosé or blush, or if the problem is really severe, make a sparkler.

If you have no choice except to make a red, you can press out part of the batch, make a blush with that and return the pomace to the skin extraction part of the fermentation.    If your TA is so high that it can’t be corrected by a malolactic or the usual tartrate precipitation, you can do a double salt precipitation or potassium bicarbonate correction on part of the blush you extracted and add that back to your main batch.    At maturity the malic and tartaric acid of grapes is typically about 50:50 so a malolactic fermentation will drop the TA by about 25%.   Cold stabilization may drop TA by about   two g/L.    Vegetal flavours tend to be broken down by oxidation, so a délestage fermentation can assist you to unmask the fruity notes and minimize vegetal notes.   You may also need to take steps to augment the palate.   Oak chip press aid during skin fermentation can assist this.   You may also wish to add skin tannin to balance the astringency.    The more adjustments that you can make early in wine development, the better will be the final palate.   There is little to be gained by extended skin contact of immature grapes, so press them and move into an early malolactic followed by a sûr lie autolysis.    

There is also the possibility that grapes could mature early and have less than normal varietal character.    When the last thirty days of the season are above 20°C average, the rate of loss of volatile flavour compounds may be greater than their rate of synthesis, resulting in a wine with nondescript varietal character.    Add to this the grapes be overmature at harvest and the wines may lack acidity, have high pH, and high alcohol.     The easiest factor to deal with is pH.   There are several options.    If tartaric acid is added, the pH will drop by approximately 0.2 pH units per gram of tartaric acid.   Initially the TA will rise by the same amount as the added acid, but the tartaric acid will eventually precipitate as potassium bitartrate, thus removing potassium ion and leaving the pH at the lower level.    Citric acid or malic acid have approximately the same effect, but they are more soluble and will not precipitate.   Thus the TA will remain at the adjusted level.    Use care with citric or tartaric acid to ensure that no malolactic fermentation is initiated.

To develop more intense varietal character, the extraction from skins must be enhanced.    This can be accomplished either by extended skin contact or by the use of pectinase to break down the berry structure, either in whites or reds.    In white wines this must be done with caution in order to assure that excess tannins aren’t extracted.    The wine may require fining to remove excess astringency, depending on wine style.

The bottom line is that a fundamentally good growing site should be versatile enough to give good performance in good or bad growing seasons.   With a little care, good wines can still be made in spite of an adverse season.

This article was first published in British Columbia Fruit Grower

Gary Strachan is an expert consultant and planner for the grape and wine industry. He can be reached at and is also listed on LinkedIn.



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“Late-season fertigation of wine grapes is too late”… “La fertirrigation tardive de la vigne est trop tardive”…

 “Late-season fertigation of wine grapes is too late”… We can demonstrate the opposite!

While fertigation has become an integral part of the cultivation of many crops, it is rarely used by grape growers. Certainly in part due to dogmatic reasons.

On the contrary, vineyard irrigation has experienced a significant development. With the scientific knowledge we have today, we are able to manage irrigation in order to achieve specific quantitative and qualitative production goals. The monitoring methods and available technologies are numerous, each with its own advantages and disadvantages.

From a scientific point of view, very few studies have addressed the subject of vine fertigation directly. From a practical point of view, the experimental data is still scarce.

Fertigation is the best method for efficient vineyard nutrient management,  while being competitive as well as sustainable.

Fertigation has many technical advantages:
-  improved availability and superior nutrient uptake.
- effective nutrient distribution.
- nutrient management based on the vine vegetative cycle and production objectives.
- incorporation of nutrients in dry climates and/or drought periods.

Our topic of interest is late-season fertigation.  What do we mean by “late”? It is fertigation which is administered after veraison, more precisely 15 days after veraison.

These are the four major advantages of late-season fertigation:

Maintaining yield potential and berry shrivel

After fruit set, berry volume is the only factor responsible for a yield increase. The number of clusters and the number of berries per cluster are predetermined and can only be significant  for yield decrease (due to hail, diseases, pests, etc.).

Late-season fertigation allows us to maintain the berry volume and to avoid berry shrivel, which can be detrimental to berry quality (specifically with the development of harsh tannins) and quantity (yield loss). This is especially important for varietals where berry shrivel is more common (Merlot, Tannat, Pinot Noir, Gamay etc.). Cabernet Sauvignon, however, is less sensitive.
We tested the accuracy of the human sensor (the eye) for the detection of loss of berry volume. Our results show that when a decrease in berry volume is established visually, the berry shrivel point is often already reached and the berry volume loss is greater than 20 %, which is considerable. This compares to a yield loss (in susceptible varietals) of up to 30% in less than a week.


For a berry with a volume of 1.5 mL, a decrease in diameter of just 1 mm is equivalent to a yield loss of more than 20 %.

Some experiments in France show that it is not possible to increase yield by more than 30 % with irrigation. This is both true and false.

It is true if one considers only the current year and only after fruit set: the single factor affecting yield is the volume of the berry, which cannot increase indefinitely or otherwise the berries will burst. A threshold of 30-40% yield increase is an acceptable average value (this being dependent on the grape variety).

However, the claim that yield cannot be increased by more than 30% with irrigation is also false, since the yield is already predetermined in the previous year (n-1) during flower initiation and at the beginning of the current year (n) with floral differentiation. If our main objective is yield, we can adapt the vineyard operations after pruning, specifically after the post-harvest fertigation of year n-1 in order to set aside a good reserve.


Vine root activity is dependent on the vegetative cycle and reaches a peak during harvest. Therefore, at this time the vine is able to assimilate any available nutrients, especially if water is available.  There can be no assimilation of nutrients without available water, which is another point in favor of fertigation in dry climates or during dry periods.
This is one of the reasons why a nitrogen addition post-harvest improves the formation of sugar reserves, fundamental for a good bud break (vine growth cycle starts with spending these reserves).







Note that also phosphorus and to a lesser extent potassium enhance the effect of water on berry volume increase, with small added amounts (5-10 kg/ha).






Late-season deficit, aromatic profile and blocked maturation

As mentioned above, one of the major advantages of fertigation is to provide the plant with nutrients along with water. Therefore, the nutrients become assimilable.

During summer, especially in the Mediterranean climate (but not exclusively), the roots stop assimilating nutrients because of a lack of water in the soil.

In other words, when a nutrient deficiency is  observed (nitrogen or potassium, for example), it is already too late, it is no longer possible to take action. Even foliar spraying is not really effective.

Late-season fertigation resolves nutrient deficiencies which cannot be resolved in any other way. That said, it does not solve all problems because at the time we notice it in the vineyard, it has already been about 3 weeks that the deficiency has been present.

We also found that late-season addition of phosphorus in small amounts (2 x 5 units (kg/h) within 20 days before harvest) increases the intensity of “fresh fruit” aromas in Merlot.

Another important point is that fertigation helps with blocked maturation (due to water stress), specifically with the intake of phosphorus.

Blocked maturation occurs when the transport of sugars to the berry stops before the grapes reach maturity (a plateau in terms of amount of sugar per berry).  In other words, if the concentration of sugars in the berry keeps increasing, we cannot be sure that there is no blockage of maturation. The reason could be berry shrivel, instead.

Finally, with late-season fertigation with phosphorus and potassium, it is possible to manipulate the harvest date (maturation determined by the amount of sugar per berry). Phosphorus delays ripening and potassium accelerates it.




Ms. Biljana Petrova (Laboratory Manager Inozy) is gratefully acknowledged for her English translation.


“La fertirrigation tardive de la vigne est trop tardive”… Nous allons vous démontrer le contraire!

Tandis que d’autres cultures l’ont déjà bien intégrée, la fertirrigation – ou irrigation fertilisante – est une pratique peu employée sur vigne. Certainement en partie pour des raisons dogmatiques.

Au contraire, l’irrigation seule de la vigne s’est considérablement développée. Nous disposons aujourd’hui des connaissances scientifiques suffisantes pour piloter l’irrigation en fonction d’objectifs-produits quantitatifs et qualitatifs. Les méthodes et capteurs sont d’ailleurs nombreux, avec chacun des avantages et inconvénients.

D’un point de vue scientifique, peu de recherches ont traité directement du sujet de la fertirrigation. Et d’un point de vue pratique, les expériences sont trop peu nombreuses.

Et l’un des meilleurs outils pour fertiliser la vigne, c’est la fertirrigation. Elle permet en effet d’être très performant pour piloter son vignoble de manière compétitive et durable.

La fertirrigation présente également de nombreux avantages techniques :

- meilleure accessibilité et meilleure assimilation des engrais.

- distribution efficace des engrais.

- pilotage possible en fonction du cycle végétatif et des objectifs-produits.

-  incorporation des engrais sous climat sec ou en période sèche.

Nous nous intéressons ici à la fertirrigation tardive. Qu’entend-on par « tardive » ? Nous retenons une fertirrigation qui a lieu après véraison, plus précisement 15 jours après véraison.

Nous présentons ici 4 intérêts majeurs de la fertirrigation.

Maintien du potentiel rendement et flétrissement

Après nouaison, le seul facteur qui peut permettre d’augmenter le rendement est le volume de la baie. Le nombre de grappes et le nombre de baies par grappe sont fixés et ne peuvent que potentiellement diminuer (grêle, maladies, ravageurs etc.).

La fertirrigation tardive permet de maintenir le volume de la baie, et d’éviter un flétrissement préjudiciable à la qualité (notamment un durcissement des tanins) et à la quantité (perte de rendement). Ceci est d’autant plus important pour des cépages qui flétrissent facilement (Merlot, Tannat, Pinot Noir, Gamay etc.). Le Cabernet-Sauvignon quant à lui, est peu sensible au flétrissement.

Nous avons testé la précision du capteur humain (l’œil) pour la détection d’une perte de volume de baie. Nos résultats montrent que lorsqu’on constate une diminution du volume de la baie (visuellement), d’une part le stade flétrissement est très souvent atteint, d’autre part la perte de volume est supérieure à 20%, ce qui est considérable. Ce chiffre est à comparer à des pertes de rendement (sur cépages sensibles) qui peuvent atteindre 30% en moins d’une semaine.


Pour une baie d’un volume de 1,5 mL, une diminution de 1mm de diamètre équivaut à une perte de rendement de plus de 20%.

Certaines expérimentations en France montrent qu’il n’est pas possible d’augmenter de plus de 30% le rendement avec l’irrigation. C’est vrai et faux.

Si nous nous plaçons après nouaison l’année de la récolte, c’est vrai. En effet, le seul facteur influençant le rendement est le volume de la baie ; il est impossible de l’augmenter indéfiniment, sinon la baie éclate. Et le seuil de 30-40% est une valeur moyenne (ceci étant dépendant du cépage).

C’est faux, puisque le rendement se fixe en grande partie l’année N-1, lors de l’initiation florale, et au début de l’année N avec la différenciation florale. Si on raisonne objectif-rendement, on adapte l’itinéraire viticole depuis la taille, voire même depuis la fertirrigation post-vendange de l’année N-1 pour une bonne mise en réserve.


L’activité racinaire dépend du cycle végétatif et atteint un pic pendant les vendanges. A cette période, la vigne va donc pouvoir assimiler les éléments minéraux à disposition. Et ce, d’autant plus qu’elle a de l’eau disponible. Sans eau, pas d’assimilation d’éléments minéraux. C’est encore un point en faveur de la fertirrigation sous climat sec ou en période sèche.

C’est la raison pour laquelle un apport d’azote post-récolte permet d’améliorer la mise en réserve de la vigne, point fondamental pour un bon débourrement (la vigne démarre son cycle en déstockage).






Notons également que le phosphore –et dans une moindre mesure le potassium- accentue l’effet de l’eau sur l’augmentation du volume de la baie, avec des quantités faibles (5-10 unités).






Carences tardives, profil aromatique et blocages de maturation

Comme évoqué plus haut, l’un des intérêts majeurs de la fertirrigation est d’apporter des éléments minéraux avec de l’eau. Par conséquent, ils sont assimilables.

Or, en période estivale, notamment sous climat méditerranéen mais pas exclusivement, les racines n’assimilent plus les éléments minéraux par manque d’eau dans le sol.

Autrement dit, lorsqu’une carence minérale est constatée (azote ou potassium par exemple), c’est trop tard, il n’est plus possible d’agir. Même les pulvérisations foliaires ne sont pas réellement efficaces.

La fertirrigation tardive permet de résoudre les carences impossibles à résoudre autrement. Ceci dit, elle ne résout pas tous les problèmes, puisque lorsqu’on constate une carence au vignoble, cela fait environ 3 semaines qu’elle était présente.

Nous avons également constaté qu’un apport tardif de phosphore à faibles quantités (2 fois 5 unités dans les 20 jours précédents la récolte) augmente sur Merlot l’intensité aromatique Fruits Frais.

Aussi, et c’est un point important, la fertirrigation permet des déblocages de maturation, notamment avec un apport de phosphore.

Nous entendons par blocage de maturation un arrêt du chargement en sucre de la baie avant la maturité (plateau atteint en terme de quantité de sucre par baie). Autrement dit, ce n’est pas parce que le degré augmente qu’il n’y a pas de blocage de maturation. Au contraire, cela peut signifier un flétrissement.

Enfin, avec le phosphore et le potassium en fertirrigation tardive, il est possible de piloter la date de récolte (toujours par rapport à une maturation déterminée par la quantité de sucre par baie). Le phosphore retarde la maturité, et le potassium l’avance.




Mlle Biljana Petrova (Laboratory Manager, Inozy) est vivement remerciée pour sa traduction anglaise.

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