Vine phylloxera – Online Plant Sales

Today I am in a very important place in my life, linked precisely to the origins of my family, this is the Àaschina farmhouse (Vaschina) and we are in the same village in the lower Brescia area where the nursery is located, the locality of Viadana Bresciana, in the municipality of Calvisano (BS).

The one behind me (you can see it better in the video above) is one lives of about a century of ageand today together with her, I will tell you the troubled history of the vine and how man prevented it from completely disappearing at a certain point in history due to the much feared phylloxera of the vine.

The screw in short

The common vine or Eurasian vine (Vitis vinifera) is the species of the Vitis genus most cultivated in the world and is present in practically every continent. There are different vines, that is, varieties, declinations of the type species that bear names such as Chardonnay, Nebbiolo, Lambrusco. Some are more suitable for winemakingthat is, the transformation of grape juice into wine, through alcoholic fermentation. Others are more suitable for table consumption.

Probably already at the end of the Neolithic, around 3500 BC, man had noticed by chance that some grapes left in some containers had fermented. And so began a thousand-year history between man and plant, a history dotted with numerous ancient testimonies, from the Sumerians to the Egyptians.

The Greeks introduced viticulture to Europe, while the Etruscans and Romans made great contributions to the cultivation technique.

Vitis vinifera is not the only ‘grape plant’ but it is certainly the one that gives us a fruit suitable for winemaking.

However, there are other species of the Vitis genus, the so-called American vines: such as V. riparia, V. ruperstris, V. berlandieri, V. aestivalis. These are plants that have been cultivated since ancient times by local populations with the aim of producing fruit for fresh consumption. On the other hand, however, they generally do not offer a fruit suitable for winemaking. An attempt was made to import the European vine into America, obviously, but the first cultivations were not very successful and we will later understand why.

When did phylloxera arrive in Italy?

However, not everyone knows that, between the end of the 19th century and the beginning of the 20th century, the vine as we know it risked disappearing completely. It is estimated that between 65% and 90% of European vineyards were destroyed in these decades.

The nineteenth century was a bit unfortunate for the vine: two fungal diseases seriously threatened the crops: downy mildew and powdery mildew. The vine is still sensitive to these cryptogams but it was soon discovered that copper and sulfur-based treatments were particularly effective.

However, there is a third plague, much tougher, which threatened the vineyards in the same years and to resolve it required a much greater effort than a coat of verdigris.

Vine phylloxera: an invisible enemy

We are in 1863 in France, in a village in Languedoc, one of the most intensely cultivated vineyard areas. Vine plants present strange symptoms: the leaves turn yellow, red and fall.

The problem extends to nearby vineyards and the following year the affected plants are deadso the farmers proceed with the uprooting and, just like we do with our plants, inspect theroot system that appears rotten, necrotized. However, there is no trace of parasites.

It took a while to understand that the problem was an insect, specifically an aphid, which we now know as vine phylloxera. Like the most common aphids or plant lice that we must manage on our ornamentals also the Phylloxera is a phytophage, about 1 mm.

Phylloxera, what it is and how it works

Phylloxera is called monophagous because it specifically attacks the vineunlike other polyphagous parasites which can instead parasitize different kinds of plants.

But what damage does phylloxera cause? There are two parts of the plant susceptible to attack by phylloxera: the roots and the leaves.

The insect causes the formation of growths called galls on the leaves, produced by the plant in reaction to phylloxera bites. Hundreds of eggs are laid inside these galls which release as many individuals when they hatch.

The complete biological cycle of phylloxera is very complex and therefore I am simplifying as much as possible.

To feed itself, phylloxera has a mouthparts equipped with a rostrum, a sort of needle that it can insert into the tissues of the plant to suck in its lymph and cellular juices. Some individuals born from the galls have a shorter beak and continue their life on the leaves, others have a more elongated mouthparts and descend the trunk of the plant to parasitize the roots.

The juvenile forms (called nymphs) that arrive on the roots begin to pierce them to feed and this causes deformations and lesions, often also associated with the appearance of secondary parasites such as mites and fungal diseases. Slowly the roots lose their conduction function and decay, usually in 3 years the plant dies.

Phylloxera is a very clever insect, in fact the French did not find it immediately because before the host plant dies, the phylloxera individuals abandon it and position themselves on the roots of the next victim.

Where does phylloxera come from?

Why had no one ever detected the presence of this parasite before 1863? In reality, someone had already described it, but not in Europe, because it had never been here before. It had been described by an American entomologist a few years earlier, in 1856.

The hypothesis was immediately put forward that phylloxera arrived from Almericaimported together with some American vine plants or through the essences that naturalists brought from overseas to European botanical gardens.

This hypothesis, which has always been considered valid, was then supported by a 2020 publication on the study of the insect genome.

The solution against vine phylloxera

There is one particular thing about phylloxera infection on grape plants to be aware of. We said that the damage is of two types: to the leaves and to the roots.

What needs to be specified is that European vines are not affected by leaf damagewhich do not react to phylloxera bites, preventing the formation of galls. Therefore in European vines the infection and the population of the parasite are essentially localized at the root level. Missing the part of the biological cycle on the leaf, on the other hand, Root infections on European vines are much more virulent and harmful.

American species, on the contrary, are susceptible to leaf attacks and react with the formation of galls. The damage itself is limited because it occurs early in the growing season and at a certain point, after the moment of oviposition, the leaves that are produced are healthy.

But what is most interesting about American vines is the developed genetic resistance against root attacks: phylloxera still carries out the root cycle but its attacks, although causing deformations on the roots, do not compromise their vitality and ability to conduct the sap.

In short, for this reason it took more than 30 years to resolve the phylloxera situation but the turning point was to understand this substantial difference between European and American vines.

Phylloxera, how to fight it

That’s enough graft European vines onto one foot (as they say in jargon) of American lives. What it means: it means taking the root system and a part of the stem of the American vine, whose roots we have seen are resistant to attacks by phylloxera, and inserting the buds of the European vine that we want to grow on top.

I won’t go into detail about grafting in general or that of the vine because they are topics developed in entire books, but from the end of the 19th century onwards, European vine plants, with some exceptions which I will mention in conclusion, have all grafted onto a rootstock of American vines and related hybrids.

When a winemaker buys the vine plant to plant in the vineyard he usually buys a cutting, that is, a small grafted bare root plant: the lower part is that of an American vine, but the buds that will start developing vegetation and fruit will be those of the desired vine.

This is why the first European vines brought to the United States did not give great results, they were attacked by phylloxera without anyone having yet identified the problem.

The graftwhich now affects not only the vine but many fruit trees and also many ornamental plants, gives particular characteristics to the plant: for example morphological (there are, for example, dwarfing rootstocks) or resistance to particular environmental factors (for example to cold)

What mattered to winemakers was that the rootstock did not alter the characteristics of the fruit that is borne by the scion. And so, in fact, it was.

Are there, today, vineyards with European vines that have not been grafted onto American vines?

Although almost all the vineyards in the world are made up of grafted vines, there are some curious exceptions, in this case we are talking about ‘ungrafted’ vines: the Chilean vineyards, for example, enjoy in some way geographical isolation such that phylloxera has never reached us there. Even in the State of Washington (USA) phylloxera has never been present and, in Australia, it is only present in small, very limited areas; then Cyprus, Santorini, a small medieval village in Spain and an estate in Portugal.

Vineyards without phylloxera in Italy

Even in Italy there are some vineyards never affected by phylloxera: an estate in Montalcino that produces a wine called ‘prefillossero’ from Sangiovese grapes coming from a vineyard planted at the end of the nineteenth century, some in the Aosta Valley and on Etna and still others in the province of Ascoli Piceno and Ferrara.

In general they are crops planted on very sandy soils are immune because phylloxera does not find sufficient continuity in these coarse-grained substrates to be able to move from one root system to another. Likewise, it dislikes very clayey, heavy, asphyxiated soils which, however, are not congenial even to the vine.

Is grafting necessary for vine phylloxera?

To date, it is a rather shared opinion among experts that without the grafting solution we would not have a wine industry in the world or at least not as we know it today.

However, we all agree that this method is the most effective and usable for immunizing European vines from phylloxera.

It took decades to rebuild European vineyards but it was a great victory and a first lesson on the dangers that accompany the movement of plants and related parasites around the globe.

Fortunately in this case the enemy’s homeland, America, also gave us the definitive weapon to defeat him. In short, a story with a noteworthy plot!