Source: Wall Street Journal – 19 June 2019 A blight-tolerant American chestnut tree is the latest example of what the science community has begun to call a GRO—a genetically rescued organism. In the past century approximately four billion chestnut trees have been lost in the U.S. due to blight that spread when the Cryphonectria parasitica fungus arrived with chestnut trees imported from Asia. A once-dominant hardwood species is now rare.