The early symptoms of the disease appear from the latter half of June to the middle of July, when the leaves on one or more branches may wilt, droop and curl. The leaves then turn brown and usually remain on the tree. If the tree is infected later in the summer, the leaves will droop, turn yellow and drop prematurely. Late season infections are easily confused with normal seasonal changes in leaf color.
Early Symptoms - green, wilting leaves
Mid Summer - Clinging, brown, wilted leaves
Tree showing flagging
All of these symptoms are accompanied by brown staining in the sapwood that can be seen by removing the bark of infected twigs.
The left piece of wood shows the brown staining of the sapwood from a new infection of DED; the central piece was infected the previous year by DED and the far right piece is not infected.
For information about STOPDED or Dutch elm disease, email firstname.lastname@example.org or call the STOPDED Hotline: 1-877-837-ELMS (3567)