It was a month before harvest. We were told that our grape order with a Walla Walla vineyard could not be fulfilled due to a light crop this year. Thinking that the unseasonably warm weather might be the cause, we switched our order and went with a Yakima vineyard instead. Then through the grapevine (no pun intended), I learned about the real culprit - phylloxera!
|Cartoon from Punch, September 6, 1890|
You may have heard of the phylloxera epidemic in Europe back in the 19th century. The vineyards there were severely decimated, bringing the wine industry to its knee. It started when American vines were brought across the Atlantic Ocean to be studied. Unfortunately, little pesky stowaways went along with them and somehow snuck into the vineyards.
Phylloxerae are microscopic insects that feed on the leaves and roots of the grapevines. In the roots, they can cause critical damage and introduce a secondary bacterial or fungal infection, eventually starving the vines of nutrients and water. It was estimated that over 40% of the French vineyards were devastated over 15 years during the plague.
|Champagne vineyards once devastated by phylloxera|
The grafting approach was wildly successful in saving the European grapevines, also known as Vitis vinifera. You can thank the American rootstock as you sip your glass of Bordeaux or Barolo.
Dodging the Phylloxera Bullet?
Many vineyards growing Vitis vinifera grapes have preemptively avoided the threat of phylloxera by planting only vines that are grafted on resistant rootstocks. But there are areas in Europe and beyond that have remained unscathed by the louse. Apparently, phylloxera does not survive well in the slate soil of Mosel or the volcanic soil of Mount Etna. Grapevines in those areas are still grown in their native rootstocks.
Phylloxera also tends not to thrive in cooler climate. Until recently, Washington had been virtually phylloxera-free and was able to grow Vitis vinifera in their native rootstocks as well. However, with climate change, phylloxera has started making inroads into a few Walla Walla vineyards leading to an outbreak in 2019.
|Phylloxera does not tolerate cold winter|