Phylloxera is a tiny aphid-like insect the most dangerous of all vine pests. It attacks the grapevine by sucking on the leaves and/or roots and releases its saliva into the sap pathways. This causes galls (growths) to gradually cut out the flow of nutrients of the vine and damage the root. It further causes other infections such as fungal and bacterial resulting in vine death.
The spread of phylloxera was soon after a cure of the two mildews which attacked Europe vines, powdery mildew, and downy mildew. Most of the vineyards for wine grapes in Europe were destroyed. When the dead vines were dug up, it was discovered that the entire root system had practically disappeared. Due to the tininess of the insect, it was initially unidentified as the cause of this infestation. Different species were suspected due to different behavioral patterns towards the vine.
The German biologist Dr. Carl Borner (1880 - 1953) discovered two different species: the less dangerous long-nosed phylloxera and a more harmful short-nosed phylloxera. The insects are thought to arrive in France in the 1860s either in the wood used for packaging material from the US to France or in the shipment of American Vines. However, other sources state that phylloxera was introduced to Europe when avid Botanists in Victorian England collected specimens of American vines in the 1850s. How this phylloxera aphid was introduced to Europe remains a debate.
This vine pest has a cycle, during its time to lay eggs they move beneath the ground feeding on the root system, while above ground they feed on leaves, and it multiplies in hundreds in a short period. The infestation in the vineyards spread easier where a high planting density was in place. However, dispersal was assisted by other natural factors including wind, birds, and animals also the possibility of human-assisted dispersal by tools, machinery, planting material, soil, and other sources. The infestation was terrible, viticulturists and businesses were losing their crops and thousands of families whose lives depended on the wine business were in despair.
Phylloxera louse was said to be first discovered in the South of England in 1863, followed by France in 1866 in Rhone Valley and Languedoc. In 1869 phylloxera reached Bordeaux. Experiments began with several different attempts that failed some of which were the flooding technique, vineyards were flooded with water coming from man-made canals, insecticide trails, treatments using volatile chemicals, experimenting with different soil types, adding volcanic ash from Pompeii, and more. A reward of 20,000 Francs was announced by the Minister of Agriculture to anyone that finds the cure for this devastation by phylloxera.
The spread continued further, between 1871 and 1874 it was discovered in Portugal, Turkey, Austria, and Switzerland. In 1875 phylloxera was found in Italy and later that year also in Victoria, Australia. In Germany presence of phylloxera was confirmed in 1881. As well as in Algeria in 1885, Croatia in 1897, and Greece in 1898. In the 1980s phylloxera affects vines in northern California and in the 1990s Oregon and New Zealand also were affected.
All European vines were almost destroyed until it was discovered that the native American vine was immune. Every vine in Europe had to be replaced with a Vitis vinifera (the European grapevine) grafted onto a cutting of an American rootstock which is resistant to the damage caused by phylloxera. In 1878 grafting of vines onto resistant American rootstocks begins in France. Vitis vinifera and other hybrids were grafted to a rootstock that was resistant to phylloxera.
American grape variety is tolerant as it evolved for thousands of years, being productive and striving in the presence of phylloxera. American rootstocks have a good defense mechanism and roots manage to heal from wounds caused by phylloxera. Some evidence also shows that the insect is disturbed by the sap clogs and is uncomfortable for them to feed and breed this slows down its multiplication. Different types of rootstocks will show different characteristics when grafted even if the scion is from the same variety. This will differ in budburst, flowering, yield, and harvest, and will also reflect in the components of the grape acidity, sugar, ph, and other grape components.
Graft union was not something new, fruit trees and shrubs were grafted onto rootstocks for other purposes. However, the idea to graft a noble French variety onto a wild American rootstock was not taken easily. The thought that initially this pest was introduced to French soils from American vines was arduous to accept. There was also the fear that grafting would affect the flavour characteristics of the wine; which further studies concluded in no case, but in such desperation, anything was worth a try.
Rootstocks that are mostly used are Vitis species, new rootstocks are from native or hybrid with native species. Characteristics of the two species are normally found when crossing the two species. A grafted vine has two parts, the scion variety (e.g., Chardonnay) which will eventually be the top part of the vine above the ground as part of the top trunk, and the rootstock variety (e.g., Paulsen 1103), which will be the root system and lower part of the trunk. The scion and rootstock are joined which is referred to as the Graft Union.
Several hundred genetic types of phylloxera are documented around the world. Research and studies continue to combat phylloxera. Further investigations showed that phylloxera has mutated and can result in being resistant to some rootstocks.
Strictly, quarantine boundaries have been in place to prevent the spread of phylloxera in zones where phylloxera is not present thus far. Most Chilean wine has remained phylloxera free this might be possible due to the geographical land protected by the Andes mountains to the east and the Pacific Ocean to the west also the natural borders with the northern Atacama Desert and South Patagonia glaciers. Barossa Valley, South Australia has a large area of pre-phylloxera vines. Soils here are old and varied from volcanic activity, and sand is present.
Parts of Mosel, Germany is still un- grafted this might be protected by the type of soil. Italy has a couple of vines that survived which are still pre-phylloxera e.g. Alba Region ‘which is in the northern part’, Costa d’Amalfi ‘southern coastal region.' On the Island of Sicily, phylloxera was present but the vines still strive due to the distinctive volcanic soils that surround Mount Etna. In Spain within sandy areas, some pockets in France and other isolated zones around the world are known that have escaped this blight so far.
A bottle of wine from ungrafted vines pre-phylloxera of a European origin is very likely to be rare, expensive, and sought after since yields are small and expensive to maintain. Wines are often labeled with the information stating the pre-phylloxera vines, ‘old vines’, ‘un-grafted vines’, and ‘ancient vines.’ In French, the term 'vielles Vignes' is used and while the term used in Italy is 'Vigne vecchie.' These ancient vines are prestigious and amongst them not only with-stood phylloxera but also two World Wars. These wines are desirable having the richest flavour concentration of fruit with ample complexity and character.
Phylloxera is slow but damaging. It’s been years since the first invasion with several ongoing outbreaks around countries in Europe and throughout the world. This changed the world. No cure was found despite the continuous effort. Therefore, sadly remarking almost all vinifera vines on their own roots will someday be affected.