Grafting, the most sustainable way to control phylloxera over 150 years | Greffer, la solution la plus durable contre le phylloxera depuis 150 ans

International audience

English. Just over 150 years ago, phylloxera, Daktulosphaera vitifoliae, was introduced to Europe, and particularly France, from North America via imports of American Vitis plants. This aphid, with its complex biology and life cycle, has spread rapidly to most vineyards, causing rapid and lethal decline of V. vinifera vines due to the primary and secondary damage it causes to the roots. In response to this pest, and given the economic importance of the French wine sector, professional representatives organised into ‘agricultural societies’, scientists and public authorities rallied together to identify the exact causes, seek solutions and try to stem the serious socio-economic crisis that ensued. What happened in the second half of the 19th century and the decisions that followed have shaped the way in which vines are grown and wines produced in France and around the world to this day. Among the solutions identified, grafting onto rootstocks of American Vitis or interspecific hybrids naturally resistant to root phylloxera gradually came to the fore for its many advantages. At the time, and compared with other methods, it was seen above all as a method that could be applied at large scales, was sustainable (over the life of a vineyard) and had less economic impact for winegrowers. The advantages outweighed the disadvantages and risks. An intense activity to create rootstocks then began and most of the rootstocks used today were created and selected between 1880 and 1920. Once the crisis had passed and the vineyards had largely been rebuilt using grafted plants, interest in research into phylloxera and rootstocks declined sharply. Vigilance remained the order of the day in countries and vineyards where V. vinifera vines were still grown un-grafted. Over the long term, and while phylloxera is still a threat, the advantages of grafting have been established in terms of the sustainability of resistance (that have not been circumvented to date) and the low (or even non-existent) environmental impact. Many other benefits have also been derived from this practice, far exceeding the initial objective: adaptation to many pedo-climatic conditions for the same grape variety, to other pests and diseases, production lever for qualitative and quantitative choices. It can be considered the first widespread biological control method in agriculture, based on a nature-based solution.Recently, there has been some controversy, accompanied by some encouragement to grow non-grafted vines, about the possible responsibility of grafting for the health decline of vineyards, the loss of biodiversity and the lower quality of wines, criticisms that have never been scientifically proven. Since the end of the twentieth century, a number of research projects have enabled us to learn more about the biology of phylloxera, its genome, genetic diversity, the genetics of resistance to phylloxera in Vitis species and other characteristics of interest, rootstock x graft interactions and grafting. In recent years, renewed interest in rootstocks as a major lever for adapting to climate change and for agro-ecology has revitalised research in this area. New studies are also necessary to understand the recent problems of decays in un-grafted vineyards around the world, which could be linked to a development of phylloxera populations because of climate change and of more aggressive strains.This paper will review the history of the phylloxera crisis and the search for ways to combat it. It will review the latest findings on phylloxera, the genetics of the insect and the resistance of Vitis to this aphid-like pest. It will address the question of grafting and rootstocks, based on historical data and the most recent research carried out in our laboratories. It will look at research into alternative methods that could provide a solution to the current problem of un-grafted vineyards. It will attempt to respond to certain controversial issues. Above all, it aims to recall that phylloxera is not an issue of the past and that the utmost vigilance is required. Despite certain disadvantages that we have only been able to assess in hindsight, grafting remains today the most sustainable means of combating phylloxera and meeting the viticultural challenges of tomorrow.