March 24, 2019 • 2 min
Some 150 years after the Great French Wine Blight, European vines – climbing plants that produce grapes – are under threat from a disease that originated in the Americas. A bacterium known as Xyllella fastidiosa causes Pierce’s disease, in which the plants’ transport vessels become blocked, cutting the supply of water and nutrients to the leaves. California’s Department of Food and Agriculture spends about $40 million a year to control the leaf-hopping insects that carry the bacteria from plant to plant in that region. Without this expenditure, the annual cost to the wine industry could be up to $250 million. The bacterium does not just hit vines – in the Americas, it also strikes citrus and coffee plants. Now X. fastidiosa has reached Europe, where it has earned another name – the ‘Ebola of olive trees’. In 2013, it was spotted in a few olive trees in southern Italy, and by 2015 had infected up to a million trees there with what has become known as olive quick decline syndrome. So far, 359 plant species in Europe have been identified as being vulnerable to X. fastidiosa, including peaches, lavender and rosemary. Some show no symptoms, acting as reservoirs for the bacteria. Others dry and die quickly. Short of controlling insect species that could spread the disease, no cure is yet known. Generally cold winters slow the spread of Pierce’s disease; however, as the planet warms, there is every chance the disease’s ranges could increase.