On December 13, 1838, French botanist Pierre-Marie-Alexis Millardet was born. He is best remembered for his work dealing with plant pests, especially in the vineyards of France that were infested by the destructive Phylloxera in the 1860s.
Millardet attended the Collège de l’Arc and later Besançon, he studied medicine as well as nature science at the University of Freiburg and Heidelberg before becoming professor of botany at the University of Strasbourg around 1868. It is assumed that Millardet stayed there for about six years and then changed his position to the University of Nancy. 
it is believed that in 1874, Millardet was asked by the government to research the causes of phylloxera and find solutions. During the later 19th century, the phylloxera destroyed numerous vineyardsfor wine grapes in Europe and especially in France. In France alone, it is assumed that the total wine production in this period fell from 84.5 million hectoliters in 1875 to only 23.4 million hectoliters in 1889. [2,3]
Pierre Millardet and a fellow botanist named Jules Émile Planchon intended to control the infestation by using American grape vines that were believed to be resistant to phylloxera. Building on the works of Victor Ganzin and Georges Couderc, Millardet performed numerous experiments and began focusing on hybrid crosses between vinifera and the Native American varieties. His initial goal was to create hybrids that contained resistances found in native American varieties without altering the wine’s quality. Unfortunately, Millardet failed doing so, but his research was quite essential for the solution of grafting Vitis vinifera onto American rootstock. This method was probably advanced by Charles Valentine Riley and Planchon and is the preferred method until this day. It allows the customization of the rootstock to soil and weather conditions and does not interfere with the development of the wine grapes. 
At yovisto, you may be interested in a short introduction to Phylloxera and how winemakers today handle the pest.
References and Further Reading:
-  Short Biography if Pierre Millardet at Britannica
-  The Solution to the Phylloxera Problem
-  Dying on the Vine
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