PHYLLOXERA AND EUROPEAN VITICULTURE: INTRODUCTION
Phylloxera is an insect of North American origin belonging to the family of Phylloxeridae; in particular, it is a small phytophagous aphid associated with species of the genus Vitis.
Phylloxera lethally attacks both the leaf and root systems of the vine: in the first case, it lays its eggs inside knotted galls that make chlorophyll photosynthesis less efficient; in the second case, it favours irregular growths in the roots called root tubercles.
Phylloxera is a complex insect, highly efficient, and presents a different behaviour depending on the type of vine: in American vines, it attacks mainly the aerial apparatus, contrary to European vines, in which it slowly destroys the root system, bringing the plant to death by suffocation.
Like all aphids, phylloxera carries out a transformation cycle through different evolutionary stages during its life. Depending on the stage of growth, the attachment areas on the vine look well diversified. In the case of Vitis Vinifera, the life cycle of phylloxera is incomplete, making sure that the attachment remains limited only to the root zone, with the severity of infestation and damage also depending on the type of vine.
THE INTRODUCTION OF PHYLLOXERA TO EUROPE
The history of European viticulture in general and, in particular, in Italy in the second half of the 1800s has arrived at a catastrophic event. This event was a turning point in the way we perceive and experience modern viticulture and oenology: phylloxera destroyed a significant part of European vineyards, with the consequent loss of a large part of viticultural biodiversity and the destruction of entire production areas.
The exact method by which phylloxera was introduced into Europe is unknown and has been much debated in the literature. It is assumed that its arrival occurred originally through exchanges of exotic plant species used to enrich the floristic collections of European botanical gardens, including the American vine.
Certainly, in this case, too, the anthropic and sociological context has played a leading role: while in the past the routes connecting America and Europe had travel times of several months, with the introduction of steamships and technological improvements, the timing was reduced to about a week in the late XIX century. It is therefore argued that phylloxera has always been “on board” these ships, but with the long distances, it could not survive and therefore did not arrive at its destination, while with the speeding up of journeys due to the replacement of sailing ships with steamships, it succeeded in surviving and therefore spreading widely in Europe and Italy.
PHYLLOXERA: THE IMPACT ON ETNA
These events led to the first, and most impressive, step: the restructuring of the European vineyard. In its places of origin, the aphid carries out its life cycle in close relationship with the American species. The phylloxera-American vine coevolution, developed over time, has determined the emergence of trophic equilibrium relationships for resistance. These relationships, although the European vine is similar to the American vine, are partial and incomplete and lead to the death of the plant.
In Italy, the presence of phylloxera is documented from the second half of the 1800s in northern Italy, from there moving forward indistinctly throughout “the boot” even coming to devastate southern Italy. In Sicily , affecting equally, both the western part of the island and the eastern one.
AND ENHANCEMENT OF THE VINEYARD
Firriato was one of the first major brands in Sicily to deal with high mountain viticulture, arriving on Etna in the early 1990s.
The first production of Etna Rosso DOC dates back to 1994, a date that officially marks the path of enhancement and exploration of the Etna terroir.
Firriato’s journey along the north side of the Mountain continued in the following years until a real turning point, when the company acquired some parcels of vineyards located in Contrada Verzella, at a base altitude of about 650 meters above sea level. Already looking at the geological map of Etna, this land immediately appears as an intersection of different eras of the volcano, which guarantees very particular soil conditions. In this context, along the profile of Sciara, a particular vineyard has been identified that is characterized by plants that are distinguished from the classic vines for shape, size, and the formation of the trunk, often evolving in concentric circles, coils, and twisted branches, just as ancient, centuries-old vines.
In addition, after draining the soil around the root system of the group of plants that seemed to us more ancient, we had an incredible surprise: the absence of the grafting point, only ungrafted viticulture; they were totally European vines from the roots to the leaf system. We immediately realized the absolute value of this vineyard and began to apply the methods we use in our production philosophy, namely the scientific approach, hypothesis building, and validation of data through analyses carried out by research institutes.
The general belief was clear: we are in front of a vineyard with ungrafted roots and a "significant" average age, planted before the arrival of phylloxera on the volcano and survived the devastation of the infestation, and, above all, there was a need to investigate the safe presence of plants that, due to ampelographic characteristics, seem to differ from the vines known today. The next step was to submit the vineyard to a dendrological and ampelographic analysis in order to have scientific certainty about what was found inside the pre-phylloxera vineyard.
SETTING THE DATE
The Vitis Vinifera, technically, is not a tree but a deciduous liana, so it is not supposed that there is a direct proportionality between the size of the trunk and the age; nevertheless, the growth of the trunk in the vine, is a direct consequence of many variables, from the typical feature of the single vine up to the pruning techniques passing through the place where it is grown. In addition, the medullary part of the wood of this plant tends to rot over time, so the association “trunk size <–> plant age” is anything but obvious in this context.
Given the complexity of evaluating the age of a vineyard, except for the mere documentary and cadastral analysis, Firriato decided to verify the possibility of making a dating of the vineyard that adopts a scientific method, to verify and an attestation what from a first analysis seemed evident: a vineyard that survived phylloxera, planted before the arrival of the infestation on the volcano, and mostly consisting of ungrafted plants.
To deal with this complex issue, we have put in place, in collaboration with the Department of Agricultural, Food, and Forestry Sciences of the University of Palermo, a dendrochronological analysis of the wood of the vines in a statistical sample that lists the population of the vineyard.
PRE PHYLLOXERA ATTESTATION
Through an accurate dendrochronological analysis of samples and wood carrots it was possible to make the dating of a chosen sample of these plants, fixing the average age with scientific rigor and attesting an updated age of over 150 years.
Starting from published research in this sector, which informs us that phylloxera infested the north side of the volcano slightly later, starting from the last years of the 1800s, it becomes clear that the vineyard, whose plants were used as the subject of analysis, was planted before the arrival of phylloxera and survived the terrible infestation, attesting, therefore, that the vineyard is a survivor of centuries-old viticulture prior to the advent of grafting on American foot.
These results made Firriato feel that the dream came true: for a company that has always had the goal of enhancing uniqueness, exploring the wine continent of Sicily, and enhancing native vines, being custodians of a pre-phylloxera vineyard means being responsible for a unique heritage in the world.
THE SURVIVING VINEYARD - Territorial exceptionalism
HOW DID THIS VINEYARD SURVIVE?
The next question we asked ourselves, taking into consideration that Etna was and currently is infested with phylloxera, was the following: how did these vines succeed in surviving and reaching us.
In some parts of the Cavanera Etnea estate, the volcanic soils where the vineyards grow date back to very ancient pedogenetic processes, referring to previous “eras” of the volcano itself as we know it.
These pedogenetic, erosive, anthropic, and geological processes that underlie this particular area of the Etna zone have favoured the pulverization of the soil, transforming it into a soil with a high sand content. The very fine graininess that derives from it characterizes the pedological behavior consistent with its nature and the acidity of the soil itself.
As is known, this particular condition does not favour the adaptation of phylloxera to the root ananocycle, in which it attacks the root system and, consequently, protects the vine from root attack.
In a complementary way, the microclimatic conditions and the altimetric and temperature variables, which on Etna differ from subzone to subzone, affect the presence of phylloxera on the Etna territory. In fact, the spread of the aphid is favoured by specific environmental conditions: for example, temperatures higher than 10°C favour its development, with an optimum at 25°C; below this threshold, the spread of the insect slows down, and, therefore, cold climates kill this insect and limit its destructive capabilities.
The most reliable hypothesis, to date in the scientific validation phase, is that phylloxera exists in these areas; however, in the particles where this vineyard insists, the predoclimatic conditions slow down the attacks on the root systems or, alternatively, make them so slow that the vine itself is able to regenerate the root systems and therefore survive over time.
Proof of this is the absence of root bites or galls in the leaf apparatus of door grafts of American vines present in the vineyards just nearby.
THE SURVIVING VINEYARD
The anthropogenic and sociological context
There is also another reason related to the existence of this vineyard that, although less important than the phytosanitary one, is still important to understand the importance of this vineyard: The human intervention that would explain the ways in which the pre-phylloxera vineyard has survived the infection
To deepen the concept, it is necessary to contextualize the anthropic and sociological component of the period: we are talking about years in which the demand for Etna wine is constantly declining and, above all, migration from Sicily is very strong, with a substantial percentage of the population that has chosen to move to the United States, South America, and other destinations such as northern Italy and Western Europe. Even the farmers are not an exception: these are the years in which urbanization is very strong, and many prefer to seek their fortune in the cities, basically abandoning mass agriculture and viticulture.
This last aspect is decisive because the generalized habit in Sicily was and is to uproot the vineyards and renew them with vines of twenty- or thirty-year cycles in order to guarantee the productive constancy and economic sustainability of viticulture.
When the paradigm shifted to progress and the gradual abandonment of the sale of grapes and the declining demand for wine, also due to the invalidation of trade agreements with France at the end of the 1800s, the remaining farmers continued with their peculiar “family” production of both grapes and wine, thus freed from the logic of grubbing up and renewal, but did not follow the logic of replacing plants any more.
With the passage of time, therefore, thanks to the unconscious action of man, our Cavanera Etnea plants have become centuries-old and reached us, carrying an important piece of the history of world viticulture.
All these aspects have contributed to reducing the anthropic pressure on the vineyard by moving from intensive to extensive maintenance interventions.
a heritage of invaluable biodiversity.
PROTECTION OF THE VINEYARD
The discovery of unknown genotypes
Once the average age of the plants had been attestation and we had the certainty of being in front of a century-old viticulture, we decided to undertake a further strand of analysis, or that of the reconstruction of the genome of the oldest plants, with two main objectives: first, to understand if the DNA of the most famous Etnean vine, or Nerello Mascalese, could represent a different clone than those known with genome variations.attestation
The second is to understand if some of the plants, resulting in shape, branches, bunches, grapes, and leaves, are different from what is already known and therefore interesting, and if there are varieties different from those known.
After several years of meticulous analysis, it was possible to make a comparison between the DNA of these hundred-year-old specimens of Nerello Mascalese and the modern ones currently present on Etna. These analyses have allowed us to discover genetic profiles that are currently not reflected in national and international databases in the population of plants present in pre-phylloxera land.
Given the results’ absolute scientific interest, research is currently underway to continue the preservation of viticulture biodiversity and the enhancement of the ampelographic heritage present in the vineyard.
The hybrids direct producers
Some specimens of direct-producing hybrids have also been identified. These plants also originated as a response to the destruction of vineyards by phylloxera. The graft on the foot of the “American” vine was not, therefore, the first and only solution proposed by the researchers as a solution to phylloxera. The hybridization between resistant species and productive species was one of these, that is, the obtaining of a plant that had the European productive qualities but with resistance to phylloxera. This solution was abandoned because grafting was considered much simpler and more effective in the medium term, as hybridization would still have many years of research ahead for obtaining quality grapes. In this part, it is still possible to find some of these plants, not intended for winemaking but still grown for the pure preservation of the historical, anthropological, cultural, and biological heritage.
THE EXPERIMENTAL FIELD AND THE PRESERVATION OF VARIOUS RELICS
With the aim of deepening the study of relic varieties with unknown genomes identified in the pre-phylloxera vineyard, Firriato has recently reserved a small parcel for the start of an experimental field, where about a hundred individuals are planted that include the unknown genotypes, which are the object of research, and other plants of an interesting ampelographic character and of considerable historical and scientific value.
The objective of this activity is to make sure that a minimum number of plants are involved so as to guarantee an adequate study sample and begin the enhancement activities through micro-vinification, deepening the studies on the health characteristics and adaptability of plants, thus continuing the extraordinary journey of Firriato in search of the protection of uniqueness.
THE GUARANTEE OF THE CONTINUITY OF THE PREFILLOXERA VINEYARD:
To protect the preservation of this historic treasure of Etna botany, Firriato has undertaken for some time another ambitious project: to preserve the germplasm, the DNA of prefilloxeric plants, and, above all, the single “individual vine” in order to ensure the genetic continuity of The development process of the new specimens is carried out in potted offshoots. In this way, from the oldest vines, new plants are generated, which bring with them the genetic, anthropological, and historical heritage of this vineyard. Once developed, these ungrafted plants are destined to replace possibly failed plants to guarantee that this historical and wine heritage does not risk becoming extinct.