The pumice in the soil was inhabitable to the phloxera louse that destroyed Europe’s vines... Pompeii has vines 500 years old.
From the site of the other great Mediterranian volcanic eruption:
http://zesterdaily.com/drinking/santorini-greek-wine-industry/
“The soil is volcanic ash, with some pumice and other stones, but there is no organic matter, and it is astonishing that anything grows at all. There is no irrigation — the vines depend on sea mist for moisture and can also tap some water retained by the pumice stones after occasional rains.....The island is immune to the destructive insect phylloxera, for if there is no clay, there can be no phylloxera.”
Great info! Of course, there *may* be a downside to getting rid of the louse via this method...