Which insect caused the Great French Wine Blight?

• A. Grape phylloxera
• B. Powdery mildew
• C. Downy mildew
• D. Botrytis cinerea

Answer: (A)

Grape phylloxera, an aphid-like insect that feeds on grape roots, caused the Great French Wine Blight. When this root-feeding pest invaded European vineyards in the 19th century, Vitis vinifera vines suffered severe decline and death because their roots could be attacked directly, cutting off water and nutrient uptake. This outbreak was an insect problem, not a fungal one, so fungicides would not have solved it. The crucial turning point was grafting susceptible European vines onto resistant American rootstocks, which halted the spread and allowed vineyards to recover. The other listed issues are fungal diseases—powdery mildew, downy mildew, and Botrytis cinerea—which damage grapes in different ways but are not the insect responsible for the blight.