Dutch elm disease

Elm trees are one of the most important ornamental trees and are widely used in the design of urban green spaces. Dutch elm disease is recognized as one of the most important elm diseases in the world. The disease has become an epidemic worldwide and at least three species of Ophiostoma including O. ulmi, O. novo-ulmi and O. Himal-ulmi that differ in geographical distribution and invasion power, are involved in this disease. In Iran, O. ulmi and O. novo-ulmi are known to involve in this disease, with O. novo-ulmi being more virulent. Management of the disease is mainly achieved through preventive and quarantine methods, health measures, resistant cultivars and the use of chemical compounds. Various aspects of the disease, including disease symptoms and signs, pathogen biology and ecology, disease management methods are reviewed in this paper.