While the world frets over the current global pandemic, remember that vines had a grape global pandemic of their own: Phylloxera.
Phylloxera is not a virus. It is a louse originating from America and which dines on vines. The local vines in the USA were phylloxera-resistant – their roots exuded a sticky sap that gummed up the louse’s gums. However, their European cousins had no such defence.
Phlloxera is still really serious. No-one has ever found a control or cure. Serious prize-money still awaits anyone who can.
Of course, none of this was problematic until there was contact between America and Europe. European botanists delighted in collecting vines as specimens from the USA and brought them home to Europe to nurture. In their turn, aspiring American vignerons tramped across the vineyards of Europe in their muddy – and literally lousy – boots, looking for promising, flavoursome clones to take home to America. Cross contamination was inevitable. The phylloxera louse piggy-backed on the vines and the mud around the roots, and then determinedly munched its way across European vineyards. Over 70% of all French vineyards were infected and had to be grubbed up and burnt, but perhaps the French got off lightly: Phylloxera was a ‘plague’ that overall claimed 90% of Europe’s vineyards. Desperate vignerons tried almost anything to fight it: having no idea as to the cause, they would bury a live toad in the vineyard to absorb the ‘poison’. It did no good, and upset the toad.
Europeans were reluctant to re-plant with American vines which didn’t produce very good grapes – tasting wine from such grapes was not delightful. There was little point re-planting European vines that were delicious – because the phylloxera louse thought so too. The solution was to graft European vines onto American phylloxera-resistant rootstock to mange the disaster. Nowdays most vineyards in the world are grafted in this way, even our Sussex vineyards have safely grafted vines.
Little pockets of the vine-growing world remain phylloxera free: Chile is sandwiched between the mountains of the Andres and the Ocean which are both difficult for the louse to cross. Australia is protected because its an island. Closer to home, there are some places with inhospitable soils for the louse: Riesling in the Mosel is safe because the louse cannot survive the slate, and volcanic soils protect Sicilian vines. There are a handful of older individual vineyards – usually walled – which survive louse-free, but, on balance, in the global grape pandemic of the Victorian Age, the louse won.