Phylloxera

Phylloxera vastatrix (also known as Phylloxera vitifolii, Viteus vitifolii, Dactylosphaera vitifolii, Daktulosphaira vitifoliae) was introduced by experimental vines from the east coast of the USA via London to the south of France in the 1960s. By 1900, the majority of European vines (Vitis vinifera L.) were either infested or already destroyed. This devastating plague did not reach the Champagne region in the far north of the country until 1890. Initially, phylloxera was largely ignored in southern France. However, when phylloxera finally proved its truly terrifying destructive potential, every conceivable control method was tried. Even another species of louse (Tyroglyphus phylloxera), which is considered the arch-enemy of this phylloxera (but is harmless to vines), was imported. Unfortunately, this louse did not feel particularly at home in the European climate and proved to be useless. Treating the foliage with chemicals such as sulphure de carbone (hydrocarbon sulphide) appeared to have a promising effect, but ultimately also proved ineffective because it only effectively affected one stage of the phylloxera's complex life cycle. What the winegrowers did not realise at the time was that, in a practical sense, their infested vines were actually two types of phylloxera at the same time: leaf aphids (gallicola) and root aphids (radicicola).

What winegrowers discover in the foliage when their vines are infested is already an advanced stage of the phylloxera life cycle. These (leaf) aphids suck on the leaves and at the same time release their saliva into the sap ducts, which in turn causes outgrowths (galls) on the underside of the leaves. These small galls grow around the wingless aphids (gallicolae) with a small opening to the surface of the leaf. In these galls, the aphid lays several hundred tiny, lemon-coloured, oval eggs. After about eight days, new young aphids hatch from the eggs and continue to attack the foliage of the vine, forming galls again and laying more eggs. This part of the cycle produces three to six generations of phylloxera, primarily over the summer months. Finally, the leaves turn a lifeless brown colour and fall off. A proportion of the aphids on these leaves move on beforehand, while the others fall to ground level (at this stage the aphids are known as neogallicicolae-radicicolae).

Once there, they continue their activities on the root system (these aphids are now considered radicicolae). Such circumstances in the foliage must have annoyed the experienced winegrowers at the time, but certainly did not seem particularly worrying at first, as similar parasitic side effects in the cultivation of wine or even hops had long been known. What they didn't realise, however, was that even if this leaf phase of the phylloxera is rather insignificant, these young vine aphids had now also settled in the roots of their vines to overwinter there as pupae. In addition, the (root) phylloxera and the pupa are almost invisible, as they resemble the roots in colour and are also very small (0.7 - 1 mm). In spring, the vines revive seasonally, the pupae shed their skin, suck on the roots, form galls and lay eggs again. Three to six generations of Phylloxera also develop underground. Initially, the root system is not significantly damaged by the phylloxera. As soon as the end of summer approaches, some of the previously wingless phylloxera now grow wings. In autumn, they leave their underground home, infest the same vine above ground or migrate and fly to other vines, lay about 5 eggs somewhere near the ground on the vine or under the leaves of the now infested vines and die. The eggs laid are either small (male) or large (female). Approximately two weeks later, new aphids hatch, this time male and female. However, they are only intended for reproduction and have no organs for parasitic purposes. They mate, and the mother aphids now lay an olive-green or brown 'winter egg' (approx. 0.27 x 0.13 mm), usually hidden in slits in the bark of the vine. This egg either hibernates hidden in the bark, or a new (1 - 2 mm long) mother louse may hatch in the same year. This louse is considered to be the 'stem mother' (fundatrix) and turns to the fresh foliage of the vine, thus forming a gall where hundreds of eggs are laid. These then develop into (leaf) aphids and the cycle repeats itself. After two to three years, the vine dies (primarily due to root damage) and any remaining aphids move on to the next vine

If a winegrower discovers leaf symptoms, this generally means that neighbouring vines have probably already been infested for a long time. Clearing the infested vines, even down to root level, is generally useless. On the contrary: it can even encourage the spread of phylloxera, as it can be introduced into new regions via gaps and niches in tools and agricultural equipment (even through the boots of workers or even in baskets) when removing the bushes and roots, for example.

Phylloxera itself (without 'help' from humans) spreads rather slowly (approx. 25 - 30 km/year). The winged vine aphids generally only cover very short distances (with an optimal tailwind, however, 30 km are conceivable). The wingless aphids are also occasionally blown by the wind onto nearby vines. Aphids also migrate underground to intertwined roots of other vines. Climatically favourable conditions (warmer climate) promote the life cycle.

Kehren wir jedoch kurz zurück zur damaligen Champagne. Das kühlere Klima bedingte vorerst nur langsame Fortschritte der Reblaus. Die Winzer beispielsweise in Bordeaux befanden sich bereits lange tief im Kampf gegen Phylloxera, was den Winzern in der Champagne reichlich Warnung (und Erfahrung in der Bekämpfung) im Vorfeld bot. ‚Unerwartet‘ war die Plage also in der Champagne kaum. Eine Zusammenkunft aller Winzer in der Champagne wurde somit am 13. Juni 1891 in Epernay einberufen, um dem neuen Feind gemeinsam zu begegnen. Der Spruch der französischen Musketiere ‚Einer für alle und alle für Einen‘ hatte jedoch herzlich wenig mit den Weinbergbesitzern in der Champagne zu tun. Aus den damalig 25.729 Weinbergbesitzern meldeten sich nur 17.370 zum Beitritt in das neue ‚Syndicat de Defénce‘. Das Vordringen der Reblaus konnte durch dieses unvollständige Syndikat somit kaum verhindert, jedoch trotzdem etwas ausgebremst werden. Jemandem in Frankreich war offenbar inzwischen aufgefallen, dass es den ursprünglich importierten Rebstöcken aus den USA trotz der Reblaus blendend ging bzw. eine weitgehende Immunität gegenüber Phylloxera bestand. Roden der heimischen Rebstöcke war somit erforderlich, und folglich war die zügige Bepflanzung mit reblausfesten Rebstock-Unterlagen aus den USA, gepfropft mit heimischen Reben, angesagt. Trotzdem schlug Phylloxera bei den noch nicht veredelten Rebstöcken in erschreckendem Ausmaß ein. 1910 war bereits die Hälfte der Weinberge in der Marne-Gegend hoffnungslos von Phylloxera befallen.

There were and are therefore several options for winegrowers (not only) in Europe in terms of successfully combating phylloxera. By far the preferred solution in Europe was and is the use of rootstocks of phylloxera-resistant American grape varieties (e.g. Vitis riparia, rotundifolia, berlandieri, rupestris, lambrusca) with subsequent grafting of European Vitis vinifera L grape varieties (grafted vines). However, the different American rootstocks are said to have different quality and yields of vinifera fruit. According to a report in the Sonoma County Viticulture Newsletter, the leaves of the European Vitis vinifera L grape varieties are not particularly favoured by Phylloxera (see reference to the corresponding PDF file below).

Another solution was the cultivation of American vines (such as the well-known Noah and Isabella vines).

The American vines were also successfully crossed with European vines. This resulted in well-known hybrid varieties such as Baco, Delaware and Othello.

Phylloxera is historically regarded as the greatest misfortune of viticulture in France (or Europe). On the other hand, however, before this phylloxera, France was virtually flooded with numerous inferior grape varieties in often unfavourable locations. When replanting with new vines from the USA, the winegrowers made sure that only the best domestic grape varieties in their good locations received this considerable investment in labour and money for this grafting. Phylloxera also continues to be an international problem for winegrowers in Europe and many other countries (including, for example, on the west coast of the USA). In addition, the biology of phylloxera is still not fully understood. Even the famous NASA is concerned with this phylloxera. Frighteningly, there is now also talk of mutations. The battle against Phylloxera is therefore not even close to being won.

 

 

 

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