A thrillerish tale of clones, scions, chimeras and omega cuts.
Vine grafting is the close-to-magical technique of fusing a new vine cutting to an old vinestock to create a genetically-compound new plant.
In the late 1800s, it became the saviour of European winemakers as cataclysmic disease threatened to wipe out vineyards across the continent. With all its fittingly retro-futuristic terminology, grafting may well be the answer to many problems facing the viticultural world today.
Grafting, in simple terms, is the process of taking a cutting from one plant: the scion – and binding it to an established plant: the rootstock. Used across centuries and continents, grafting uses various operative techniques: cut grafts, cleft grafts, crown grafts, splice graft, whip and tongue grafts. All of which build up to (we’ll get to later) the omega cut.
The botanical equivalent of an organ transplant, in a successful graft the rootstock and the scion become one genetically compound organism (even if each maintains its individual genetic identity throughout the life of the plant).
The scion draws on the strengths of the rootstock, which acts as a donor root to the cutting. In a hall of mirrors-esque paean to possibility, any variety of scion can be grafted onto any variety of rootstock. It is the new addition – the scion – that determines the type of grape.
Grafting is crucial for many reasons. Firstly, because grapevines are almost never grown from seed. Vines are heterozygous (they carry two different alleles of a gene) making them highly prone to varietal crossing, leading farmers to discover, often years into the process, that the grape they ended up with is not the grape they planted. Because of this, clonal cutting (cutting from a mother plant and replanting), layering (bending part of an established plant so that it limboes and dives into the ground beside the original plant, where it will sprout new roots) or grafting are the most reliable ways of achieving true-to-type cultivation.
Grafting, however, has the upper hand. It allows the vigneron to take advantage of beneficial mathematics: the sum can be greater than the parts. Grafted vine varieties can flourish in soil and locations where they would struggle if stuck to their own root. Simultaneously, while the most resilient rootstocks can withstand testier environmental challenges, they might also produce poorer quality fruit than the varieties grafted to them.
Grafting gives vintners the power of remix: to adapt their vines to changing climate and blight risks, to select for increased yield and improved quality, and to change or introduce grape varieties with relative ease and swiftness, avoiding fragile and fruitless juvenile periods.
The origins of scion grafting remain hazy. Some say it can be traced back 4,000 years to ancient Mesopotamia; others suggest the colder climes of northwest Asia are the most likely genesis spot – due to less favourable planting conditions, techniques for propagation needed to be pushed to their limits. In any case, by 1767, knowledge of the technique was commonplace: Thomas Jefferson (coincidentally a very consequential fan of then-named ‘Laffite’) wrote in his Monticello garden journal that he had “inoculated common cherry buds into stocks of large kind”. Regardless of origin, most agree that the earliest deliberate grafting was likely inspired by observing spontaneous grafting – accelerated by wind, proximity, and abrasion – in nature.
These days, the process is far less incidental. Today, over 90% of the world’s vines are grown from grafted – predominantly American – rootstock. But it took a catastrophe to make it so.
The Great French Wine Blight.
As winemakers and wine-lovers well know, in the mid 19th Century, the Great French Wine Blight destroyed almost half of the grapevines in France. This decimation was the work of Daktulosphaira vitifoliae – a broad-backed, butter-yellow aphid, originally native to North America; it is thought early steamships were the inadvertent couriers of the disaster – the new, shortened journey time allowed the insect to survive on imported vines. Creating the condition of ‘grape Phylloxera’, the aphids’ attack method was the stuff of dystopian nightmares: it savaged the roots of the vine, introducing toxin from its own venom to the root as it fed on the sap.
As the plant began to die, the aphids would move onto another, healthier vine; by the time the plant showed any signs of being affected, the insects would have already abandoned their victim.
Phylloxera was first reported in the Gironde in 1869, but the Médoc area was the last region to be hit: the parasite first made its presence known at Château Lafite Rothschild as late as 1876. The previous year had been one of the most generous harvests of the century, yielding 246 barrels of wine at Lafite; by contrast 1876 produced just 83 barrels and the volume didn’t exceed 200 again for over a decade. Rumours spread to England that the Médoc vineyards had been ravaged and abandoned. These were not true, but, in every sense, when it rained it poured. Coulure ran rampant, powdery mildew played a cruel hand too, and in rather heavy-handed pathetic fallacy, the events were mirrored in the weather. In 1879, for example, spring was awful, flowering was bad, and coulure preceded an also-awful summer.
In 1880, as phylloxera spread everywhere, the race against the clock to find a cure took place in parallel. That same year, a certain Monsieur Gastine invented the ‘Pal Injecteur’, which provided a means of fighting phylloxera by injecting carbon disulfide into the soil, but it required vast amounts of water to do so: more than 12 litres per vine. This led to devastating water shortages only the largest estates could afford to solve.
The following year, however, the french botanist Alexis Millardet, famous for his invention of ‘la bouillie bordelaise’, a fungicide mixture unparalleled at beating mildew, published “Notes sur les vignes américaines et opuscules divers sur le même sujet” (“Notes on American vines and various pamphlets on the same subject”.). In it he suggested an ironic, but ultimately successful solution to the crisis. The very plants that had introduced phylloxera to France were also those that could save European vines from the blight. Using grafting to attach French scions onto American rootstocks he had created a hybridised plant, and in doing so, he had managed to bring to life immunity.
Millardet’s breakthrough birthed divergent camps among winemakers: ‘Americanists’ who adopted the technique as soon as they could, and more suspicious grand crus, like Lafite, who feared that the shift could affect quality. In the end, it would be 12 years after the discovery of the technique, and nearly twenty years after the parasite had first appeared before Lafite relented and put its trust in grafted rootstock.
Small pockets of pre-phylloxera grapes survived and still exist to this day – a few hectares of Nerello Mascalese around Etna in Italy, small areas of Ribeyrenc in Languedoc – but these are rare exceptions. Across the vast majority of winemaking in France and Italy, it became clear that grafting was the only reliable way of making European vines resistant.
The craft of grafting.
Today, on rotation, blocks of vines are uprooted, and the soil is given a sabbatical or two to rest before it is replanted – approximately 5% of blocks on a well-managed estate will be vacant at any time.
Judging when to make the call to rest a block and begin again comes with experience – the temptation to go on for just one more year is ever-present. The young and innocent might think of long-established vineyards and their aesthetically-pleasing knobbly vines as the wisened limbs of ancient plants – but the qualification for vieilles vignes is 15 years old, a mere teenager in human terms, and average age of grape-producing vines at a vineyard such as Château Lafite Rothschild is in fact only around 45 years. Most blocks will achieve around 50 years of good yield before they’re uprooted and the soil rested. At Los Vascos in Chile, there is a plot that’s now around 60 years of age and still producing excellent fruit – and Lafite has a handful of vines that are a century old. As many as possible of these proven good quality vines will be used for grafting when the time comes.
Each year, vineyard soil samples are analysed and rootstocks are ordered from nurseries around a year in advance of planting. Rootstocks are meticulously selected for their suitability to the challenges and advantages of the particular block. Vintners establish strong relationships with trusted nurseries – those with the best rootstocks and the best grafters. Nurseries raise the ordered rootstock, to be delivered en masse the following spring. Vintners then take over as deft matchmakers, inspecting every individual vine on their estates for the very best examples to marry with the rootstocks, and cuttings judged on yield and quality are sent to the nursery for grafting. On an estate like Lafite, around 30,000 vines – all grafted – will be planted each year.
The process of grafting is highly skilled – a novice might only have a 15-20% success rate even with expert guidance. But professional full-time grafters can achieve up to 90% success. The secret, perhaps unsurprisingly, is in the quality of the cut. Creating the greatest possible surface area for the two plants to form a vascular bond is of utmost importance, and the technology that has emerged to meet this need is called an Omega machine, also available in a hand-held version. It earns its name by making corresponding cuts in the scion and rootstock in the shape of the Greek letter – seen from the side, the two can slot together much like the joint of a jigsaw piece.
Even still, grafted vines aren’t bulletproof. Sometimes the grafts don’t take; and sometimes the vines lack the desired vigour. At Los Vascos in Chile, for example, we’ve found that Syrah has shown itself sensitive to dieback, regardless of the rootstock. Dehydration is a big risk to young plants – hence planting in spring to take advantage of warm, wet weather. But regardless of rain, planting in the footstep of a retired vine comes laced with the risk of older, more demanding neighbours leaving the young plant with meagre nutrients. And on top of all this, as is ever the case in the temporal headspin of winemaking, planting is always for the future. Given the length and unknown eventualities of the journey, some degree of loss is inevitable: new vines won’t be harvested until at least their third year.
By the age of five they will have become established, but it’ll be between ten and fifteen years before they hit their prime and can be expected to start producing grapes of the highest quality.
Past historic, future perfect.
The power of old, strong roots to give life – not just to their own kind, but to any grape varietal seeking adoption – has a fable-like quality about it, and it’s a story we hold onto. For its role in the repeated rhythms of our calendar, yes, but also for the unknown treasures it may yet still afford. Grafting has saved us in the past, and it may also be one of our greatest hopes for the future.
The primary challenge for any vineyard is the success of its long-term crop. In a world where the nature of seasons alters before our eyes, and predicting the future far outpaces the work of any fortune teller, grafting provides an extraordinary tool for adapting vines in a changing climate. As the wild oscillation of hotter summers, drier soils and heavier rains take hold, it will be part of our resistance in the terroirs where we are already based. It may also be a path forward in different regions, as their new potential emerges in a shifted landscape.
Success is, as ever, only to be reached through hard graft.