Olive Tree (IMAGE) Swansea University Caption An olive tree affected by Xylella fastidiosa, with visual symptoms of chlorosis and defoliation. Credit Juan A. Navas-Cortes Usage Restrictions None 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.