Blight (IMAGE) Penn State Caption The chestnut blight, accidentally introduced to North America sometime after 1904 when Chryphonectria parasitica was brought into the United States on Japanese nursery stock, killed billions of trees. It is estimated that in some places, such as the Appalachian Mountains, one in every four hardwoods was an American chestnut. Credit Michael Houtz Usage Restrictions Non commercial use only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.