I’ve got bad news for you if you’re a walnut tree. You know that parasitic fungus that’s been killing all your friends? It’s going to be tough to kill. Researchers at Purdue and Colorado State universities have analyzed the genomes of the fungus known scientifically as Geosmithia morbida and discovered that it’s surprisingly genetically diverse for a species that reproduces by cloning itself. The findings suggest that the organism experiences a high mutation rate, which gives it flexibility and will likely make it difficult for humans to control or destroy. The fungus, which is spread by walnut twig beetles, has been found across the United States and in Italy, and poses a serious threat to black walnut trees and their close relatives.