Dutch elm disease is a fungal plant disease. The fungus is most frequently carried from tree to tree by female bark beetles. The leaves on one or more branches of a stricken tree suddenly wilt, turn dull green to yellow or brown then curl and finally drop off. On young trees the progress of the disease is rapid as the fungus spreads quickly through vascular tissue and the tree generally dies within two months; older, less vigorous trees take several years to die.
The disease probably originated in Asia. It was found in Romania in 1910, in France in 1919, in the Netherlands in 1920, the UK in 1927 and the USA in 1930. By the late 1930s the disease had peaked after destroying thousands of trees. In 1970 an new outbreak was discovered in the UK.