Dutch Elm Disease

Dutch elm disease (DED) is a disease of all elm, Ulmus genus trees and specific cultivars including American, Siberian and Japanese elm. DED is caused by a fungus, carried as spores on the body of three species of bark beetles. These spores then spread into and infect the walls of the water-transport system (xylem) triggering the trees’ defense mechanism. Specialized lab tests confirm its’ presence from branch samples of suspected trees.

The beetles measure 2-3 mm in size and are generally dark brown with stiff yellow hairs on their body.

They are drawn to recently pruned, stressed or dying elm trees, where they feed and lay their eggs in the inner bark. After the young beetles mature into adults, they fly off in search of healthy elms to feed on—carrying the fungus with them, spreading the infection to other trees. The fungus remains in the tree and can also be spread to nearby elms through touching roots below the soil surface.

Native elm bark beetle European elm bark beetle Banded elm bark beetle

With a recently confirmed case of Dutch Elm Disease on August 2024 in the City of Edmonton, community monitoring is an integral part of municipal containment efforts

Look for and report to 311:

  • Sudden wilting, drooping, and curling of tree leaves on one or more major branches in the crown of the tree. Be on the look out for this to begin in early to mid-June.

  • Flagging: Leaves will turn yellow, dryout and become brown but remain on the tree. This usually begins by late June or July and stay attached into the winter.

  • Staining: Brown or reddish streaks in the inner tree tissues (sapwood) when bark is peeled away; healthy elm wood is typically cream coloured.

Safeguard our Elms: Watch and Report to 311

There are approximately 600,000 elm trees growing across Alberta. They are valued at over $2 billion dollars. With a recently confirmed case on August 2024 in the City of Edmonton, community monitoring is an integral part of municipal containment efforts.

With only two confirmed cases of DED in Alberta since it arrived in 1994, eradication of these infections is possible. Effective management of DED includes:

  • restricted pruning periods from October 1 through to March 31.

  • burning firewood where you buy it; do not transport firewood from confirmed infected areas.

  • report suspected trees with symptoms of DED

  • care of elm trees includes watering from April to mid-August