Wine 101: What is phylloxera, and how did it nearly destroy wine as we know it?

Phylloxera is famous as the pest that devastated vast areas of European vineyard during the 19th century and nearly destroyed some of the world’s greatest wine regions.

As we mentioned earlier in the month, it’s now been spotted within the Washington subregion of Walla Walla; but what exactly is phylloxera?

Grape phylloxera, a small pale yellow, aphid-like insect, is part of the Phylloxeridae which is an order of insects in the Hempitera family. It was first described during the 1860s in France as Phylloxera vastratix (devastator of vines) which was later confirmed to be the same as the previously reported Daktulosphaera vitifoliae or Phylloxera vifoliae.

Sap suckers are insect larvae which feed on grapevine roots and leaves. Its complex life cycle has up to 18 stages. They can be classified into four major types that are sexual, leaf root, winged, and root.

Sexual form infestations can begin by a single insect. Firstly a nymph lays male and female eggs on the leaf’s underside. The eggs are then transformed into male and female forms, without the mouth part. They then mat, and die. The female, however, first laid an egg during winter in the tree’s bark. This is what forms the leaf shape.

The leaf-form Nymph, also known as the stem mother or fundatrix, climbs onto the suckers-growing leaves from the rootstock. She makes galls by saliva, and into them she deposits eggs parthenogenically (without fertilization). There aren’t any clear indications of phylloxera attacks in the upper vine canopy at this time. Adults can lay as many as 200 eggs during a cycle.

Root form They cut the roots for nutrition, then release poison to seal the wounds. On older roots swellings begin to develop, and hook-shaped galls form around root hairs. They hinder the development of feeder roots and eventually cause the vine to end up dying. The root form lays eggs for seven or more generations. They is also able to reproduce parthenogenically every summer. Crawlers move to other roots on the same vine or other vines , via cracks in the soil, across the surface or in the canopy. While they’re not wings, root form crawlers can be carried by wind for short distances.

Winged form nymphs emerge in autumn , and then hibernate in the roots until spring to feed on rising sap. Eggs lay eggs beneath the leaf to restart the cycle. Nymphs are able to take on winged forms in humid areas and move to vines that are not affected so they can start new cycles.

Each vine plant may be affected in the beginning. If flying insects aren’t present, the infestation tends to spread along vine rows more quickly than when it leaps across the spacing between rows.

Plants that are damaged when they were planted will show signs and decline over the next few seasons. When a mature vineyard gets attacked, it can be a couple of years before warning signs are obvious. The only way to escape is to rip the vines.

Climate and soil type have been proven to influence the density of phylloxera populations. The bug is attracted to humidity that is both above and below the surface.

More fertile, sandy soils as well as vineyards located in schist-rich areas fared better during the 19th Century world-wide epidemic. The same applies to many of the areas which have been the most resistant to phylloxera during the 20th Century. Examples include Colares in Portugal and Santorini in Greece.

Islands are safe in the event that human transportation of the insect is controlled. Similarly, Chile has been protected by the Andes on one side and the Pacific on the other and the Atacama desert to the north.

Assyrtiko can be found in Santorini as well as Juan Garcia, which are both planted on manmade terraces in the Arribes River Canyon in Spain is possibly the only Vitis vinifera cultivars that possess the natural ability to resist phylloxera. However , the growing conditions are specific in both instances.

Very dry soils pose serious problems. If the insect manages to survive, its impact is then amplified by the absence of moisture. This can increase the severity of the recent Walla Walla outbreak.

Hard winters are thought to alter the cycle of reproduction in the phylloxera. However, climate change is believed to be playing a role in the emergence of new outbreaks, as winters get milder in many regions. Walla Walla is again one of these regions.

Most crucially for vineyard owners, American vine species have evolved alongside the insect, and thus have developed (varying) degrees of resistance. The sticky sap that they produce clogs their mouths. They can also create a protective layer of tissue around wounds to protect against infections caused by fungal or bacterial bacteria in the event that they are able to open it.

The phylloxera blight of late 19th Century.

Phylloxera didn’t appear suddenly in Europe from the air. It is believed that the insect was first introduced to Europe through specimens of American vines that were collected by British and European botanists.

The outbreak of powdery mildew that swept through European vineyards in 1850s prompted the interest in American grapes. It was believed that American vines were more resistant to diseases. The vines were still flourishing and alarm bells did not ring.

The outbreak was caused by technological advances. They included the creation of the Ward Case, a sealed glass container that let plants be placed in the sun on the deck of a ship, while being protected from spray and wind. The steamship’s advent also had a significant impact.

The first time, vineyards in Britain were destroyed. Then the issue was spread to France and a large portion of Europe. In 1863 the first vineyards began to die within the Rhone. By 1889, the total production of wine in France was lower than 28 percent, compared to 1875.

Phylloxera is the culprit

Knowledge spread slowly. Many vineyard owners lost their vines without ever knowing the reason. In France, some decided to put live toads under each vine to draw out the poison.

It’s hard to recognize the phylloxera due to its complicated life cycle. Growers seldom find healthier looking vines. They moved on once the dead ones had been removed and inspected. Jules-Emile Planchon, along with colleagues, discovered phylloxera on vines in the lower Rhone in 1866. The cause was the mistake of pulling down an active vine.

Unfortunately, this discovery didn’t lead to a coordinated response. Paris and Bordeaux experts rejected the conclusions of country bumpkins, especially those who weren’t professionals in the field of entomology, or scientists of plants.

Most importantly, they believed that the disease was a symptom rather than an actual cause. This was due to the 19th century’s obsession with the biological model of disease and focusing on internal imbalances within the plant, rather than external forces that were acting on it. They continued to seek solutions elsewhere.

Although it would take an additional five years to see the opposition completely disappear, around 1869, phylloxera had become more popularly accepted as the reason. An infested, dying vine in the southern part of Rhone was impacted by the spring floods in that year. The vineyards flourished after the insect infestation was gone.

It was noticed that sandy soils could provide some form of protection. In areas that were not considered suitable, vineyards were planted within the Rhone delta dunes. The success of these plots also bolstered the notion of phylloxera as cause.

Some figures, like Planchon, believed that the vines which were carrying the insect could also trigger a response. These theories were confirmed by prominent American figures like CV Riley, Missouri’s state Entomologist. He was heavily influenced by Darwinian beliefs and he emphasized the resistance to phylloxera in American species.

Hybrids vs. grafted grapes

Transatlantic cooperation (led by Planchon and Riley) meant that 700,000 vine cuttings came into France from St Louis over 1872-73. There was however, very little information about American vines in France and the United States. The stakes were shopped around as to between direct-producing or rootstock-based vines that are more efficient, and initial efforts focused, at great cost on the most ineffective American species.

Planchon, after returning from the USA in 1873, recommended early hybrid varieties such as Concord and Clinton, either to cultivate as vines, or make rootstocks.

But they also have a significant percent of Vitis labrusca that originates in the cooler northern forests of the US. The vines struggled in the French heat and, when utilized as rootstock materials or grown in whole plants were less resistant to phylloxera in the current conditions.

And, even more importantly, the wines were unpleasant tasting, displaying the musty, foxy hallmarks of the labrusca. Many of the producers who placed their faith in these early imports ultimately ended up in bankruptcy.

Working with grafted vines was hardly less difficult. A successful rootstock would need to graft easily, show long-term affinity with the French vinifera variety, and have resistance to the phylloxera.

The American vines required to be properly classified in the course of research, which led to new species being discovered, including Vitis riparia and Vitis rupestris. Different species possess distinct traits and preferences depending on the circumstances under which they developed. Wild vines are not all the same. of each species behave exactly the same.

The University of Montepellier’s 1870s collection of cuttings was chosen to permit the distribution and propagation of approximately 12 rootstocks. Riparia Gloire de Montpellier and Rupestris du Lot were among the top performers. The work continued in the 1890s to develop a new generation hybrid rootstocks that were better suited to French conditions.

The University of Bordeaux led efforts to develop new hybrid varieties that would not require transplants (direct producers) in competition with the Montpellier program. This was based on the idea of positive genetic inheritance that suggested that the characteristics of the rootstock of American species could be incorporated with the fruit systems of French vine parents.

This duality existed until 1900, and was less prominent around the globe until the beginning of the century. The hybrids did not have the flavor of their vinifera parent but did prove more hardy in colder climate and to resist other diseases. While generally not permitted for premium wine within the EU Many of these varieties remain stalwarts of the North American wine industry outside California, Oregon and Washington.

Other strategies to fight the phylloxera

The idea of using American vine species to fight back created a huge conflicts in France. Many considered them to be the antagonist in the story. But, more powerfully there were many people in the French wine industry were not willing to infringe on the integrity of French vineyards as well as wine by introducing alien plant material. They formulated a set of non-biological countermeasures known as La Defense based on sand and water.

The floods require a lot of infrastructure. The government was slow in planning the canals. (War with Prussia ended in 1871. The conflict and its aftermath limited the effectiveness of the French government during this time.) But there were 400.000 acres (100,000. acres) were still submerged.

The total sand plantings reached about 20,000ha (50,000 acre). Still, there are vineyards around the Carmargue Gardoise dunes of Aigues-Mortes. In sand, almost all vine nutrition must be supplied via fertilizers. The efforts to pump river silt onto the plots were only able to reinfest the pest. The winds from the coast on these sandy sites were also problematic as they carried away the sand. The wines produced were very different from those made further inland, though they were still acceptable to drink.

The Academie Francaise and the government supported insecticide trials during the 1870s. Most were laughable, all were unproductive and served to shift emphasis away from rootstock-based strategies.

Treatments using the chemical solvent carbon disulfide, as developed by Baron Paul Thenard, proved the most efficient. The oily liquid swells up in soil and kills bugs that are asphyxiating. It was particularly effective against phylloxera , but not all. It was necessary to treat the vine annually, which slowly weakened the vine. It required skilled laborers and was not available in most areas.

The pest was not as severe in the Champagne region. It was in the Champagne region that the pest was at its most widespread in the 1890s. As late as 1890 the local trade magazine was recommending the planting of alfalfa, lupins and sainfoin in the vineyards to help keep phylloxera away.

All the blind alleys eventually were closed. The greater emphasis on replanting with hybrid rootstocks came to be known as La Reconstitution. By 1900, France had the pest at least under control.

The global spread of phylloxera

Phylloxera spread to other European countries either via American or French cuttings, or by both. In the 1870s, we witnessed the destruction of Spain’s wine production, as well as Portugal Germany and Switzerland. Phylloxera was found in California in 1874 in the vicinity of the city of Sonoma. In 1900, 12,000ha (30,000 acres) were devastated throughout the state.

The Balkans and Greece were affected by the war from the turn of the century. Around the same period, Victoria and New South Wales in Australia were also affected. Other regions were also protected by strict quarantines and restrictions on the transportation of plant matter, which included South Australia.

Many French firms planted heavily in the region that is now Croatia as well as Slovenia. The vines were destroyed between 1902 and 1905, causing exodus that would boost industries of wine in North America and Australasia.

In the first 20th Century the global business could at a minimum draw conclusions reached the 30 years of debate in France. Utilizing carefully chosen grafted rootstocks on vinifera scions (and to a lesser extent resistant hybrids) appeared to stabilize the situation for most of the 20th century.

Plants and roots vs phylloxera during the 20th Century

Not all rootstocks are equally resistant. The resistance that a rootstock offers can diminish as time passes. One reason is that Phylloxera changes when it is in contact with resistant vines. There are a variety of genetic strains of phytolloxera that have been identified worldwide.

A number of vines that were grafted to AXr1 (Aramon Rupestris Ganzin no. 1) in California in the 1990s were discovered be infested. Aramon is a vinifera variety was believed to be the cause of the problem. However, other hybrids like as 41B continue to prove more efficient.

Investigative work discovered that phylloxera is mutated into Biotype B that can be overcome by rootstock resistance. Around two-thirds of the vineyards in Napa needed to be planted. The Mondavi family was forced sell their company due to the expense of replacing the phylloxera-ravaged vines.

Another point to note is that only certain rootstocks have such resistance that the insect does not lay eggs. While phylloxera is not as prevalent in grafted vineyards than elsewhere, it can still be reproduced and thrive in a lot of. This can spread later to ungrafted grapevines, as was the cut-offs from transatlantic crossings in late 19th century.

Sandy soils are not guaranteed. The Bien Nacido Vineyard, in Santa Maria Valley AVA is composed of its own root vines which are phylloxera-free to date. However, in Jumilla, Spain, Casa Castillo’s Pie Franco (French Foot) red is made from a plot of its own root Monastrell vines, planted in 1942 on sandy soils. The pest was able to take control after several years; each year, a few vines die and volumes of the wine diminish. In Champagne in 2004 Bollinger was unable to salvage one of the ungrafted parcels which were used in the Vieilles Vignes cuvee. Phylloxera was discovered six years earlier.

Indeed, many growers haven’t given enough consideration (with the advantage of the benefit of hindsight) to the choice of rootstock. This is not necessarily due to a lack of trust in soil types or other contributing aspects. The majority of these regions were developed after the 1960s, and were more focused on expanding. Grafted vines can cost three times more than ungrafted vines, and sometimes even more.

Since the 1910s, phylloxera has been around since the 1910s in Washington in some form. However, this year its appearance in the Walla Walla region was reported for the first time. The region is especially in danger because many of the growers here chose to plant self-rooted vines.

The reason was that cold winters had slowed the reproduction of phylloxera. Grated vines seem to recover slower from frost. There are also lots of sandy soils. The changing climate has made it more difficult to be successful since hard freezes are less frequent.

On the New Zealand’s South Island, phylloxera was discovered in the Central Otago wine region in 2002. Rapid growth meant it was believed at the time that just 55 percent of vines were on resistant rootstock. This was a lot lower than the figure for other regions in the country. The harsh winters did not provide enough protection for the region.

Phylloxera: present and future

There is still no “cure” for vines which have been damaged by phylloxera. There is no chemical or biological controls to prevent it from becoming established. Flooding vines is not an option. The best way to keep a vineyard from being destroyed is to eliminate it and then plant it on better rootstocks. A possible silver lining is that the grower can choose a more suitable clone, or even change the grape variety, but the financial costs could be enormous.

It is still difficult to choose the right rootstock (commercially available). Apart from the local soil and macroclimate Viticulturists must also be aware which particular strain(s) of the phylloxera they’re facing. Vinehealth Australia (formerly the Phylloxera and Grape Industry Board of South Australia) tests rootstocks against at least seven varieties.

Protocols are being designed around the globe to control the movement of people and machinery between vineyards. The machines could be steam cleaned and employees could wear specific footwear for each vineyard they have to visit.

This could also mean that the use of mechanized or manual passes through the vineyard must be avoided. In a vineyard that is affected, this might be a good idea however, other growers (especially biodynamic ones) must maintain the highest level of vigilance. This can be a voluntary measure.

Researchers are working on creating new rootstocks more resistant to the phylloxera. This is to counter the ability of phylloxera to create biotypes that can overcome the defenses of specific rootstocks. A study from 2018 (Smith et al, BMC Plant Biology) investigating the genetic causes of the phylloxera resistance of rootstocks was able to identify a single allele (RDV2) which confers this attribute.

In the year the year 2018, Vinehealth Australia reported that it has successfully tested DNA profiling techniques to detect genetic material of phylloxera in vineyard soil cores. Though sample taking is easy however, storage and transport conditions are vital (as is laboratory availability). It will take time before this becomes a common method. With the help drones for cost effective aerial imagery, at a minimum Australian winemakers could soon be able to implement a reliable early warning system toolskit.