“At least two once-common trees are now known to be critically endangered, and there could be many more,” says government forest pathologist Angus Carnegie, who examined the lessons learned from this invasion in the 2018 Annual Review of Phytopathology. One, the native guava, is at imminent risk of extinction.
To get a clearer picture of the problem’s scale and how it’s being tackled, I took a train to London and the Royal Botanic Gardens at Kew to meet Richard Buggs, who leads research in plant health at Kew. “Everyone is sharing their pests and pathogens,” Buggs tells me. “Europe has pathogens from the Americas, and America has some from Europe. The U.S. has Chinese pathogens, and China has trees dying from American pathogens. And so on and so on.” Most go undetected until they’re on the loose, and each year they cause the loss of crops worth billions of