| Pierre-Marie-Alexis Millardet | |
| Birth Date: | 13 December 1838 |
| Birth Place: | Montmirey-la-Ville |
| Death Place: | Bordeaux |
| Nationality: | French |
| Field: | botany and mycology |
| Work Institutions: | Strasbourg |
| Alma Mater: | Heidelberg Freiberg |
| Known For: | Phylloxera |
| Prizes: | 1893 Prix Morogues[1] [2] |
Pierre-Marie-Alexis Millardet (13 December 1838 - 15 December 1902) was a French botanist and mycologist born in Montmirey-la-Ville.
He was a student at the Universities of Heidelberg and Freiberg, and later became a professor of botany at the Universities of Strasbourg (1869), Nancy (1872), and Bordeaux (1876).Millardet is chiefly remembered for his work dealing with plant pests. In the 1860s the vineyards of France were infested by the destructive Phylloxera, an aphid-like pest inadvertently introduced to Europe from the United States. Millardet and fellow botanist Jules Émile Planchon (1823-1888) controlled the infestation by using American grape vines that were resistant to Phylloxera as grafting stock. American horticulturalist, T.V. Munson, was instrumental in identifying and provisioning the American rootstock that was resistant to Phylloxera and suitable for French growing conditions.
He was also responsible for protecting grape vineyards from downy mildew fungus (Plasmopara viticola). He accomplished this feat by implementing a fungicide consisting of hydrated lime, copper sulfate and water, a mixture that was to become known as the "Bordeaux mixture". It was the first fungicide to be used worldwide and is still used today.