When the Minneapolis Park & Recreation Board's (MPRB) Forestry Department determines that a boulevard elm tree has Dutch Elm Disease (DED) we must remove it. DED is caused by a fungus and is fatal to the tree. The fungus enters the tree in one of two ways. The elm bark beetle feeding and breeding causes most DED cases. The fungus can also spread to adjacent trees through grafted root systems.

Diagnosis

Diagnosing DED

Inspectors first look for wilted leaves or branches. They take a twig sample and peel back the bark confirm the disease. On a healthy elm the underlying wood is white. If DED is present the underlying wood has distinctive brown streaking.

Marking and Notification

If a tree has DED, we must remove it. We paint and orange ring around the trunk of the tree to notify the public. We also paint a large letter on the trunk of the tree to indicate which inspector condemned the tree. If the boulevard tree is in front of your home, we will leave details and contact information on your door.

If we cannot confirm a tree has DED but we suspect it does, we paint an orange dot on the trunk so we can watch the tree for additional signs of DED.

Removal

Tree Removal

We remove diseased elm trees as quickly as possible so they do not serve as a breeding ground for the elm bark beetle. Beetles fly from breeding trees and infested firewood to healthy trees and spread the fungus. That is why it is against municipal ordinances to store elm logs with the bark intact. To control the spread of DED, we must control the infected beetle population by removing dead and diseased trees.

First, we remove the top branches so the tree is smaller and easier to cut down. Then we cut and drop the main trunk of the tree into the street or other available space. We haul the large logs to a facility to recycle 98% of the wood.

The woodchips generated from tree removal are available to the public at free woodchip distribution sites. Using elm woodchips does not spread DED.

After we remove a boulevard tree, we measure the stump and paint the size on the cut surface. If you see this mark, it means we recorded the stump and will grind it in the future. Usually, we need to grind the stump so we can plant a new tree.

Treatment

Treating Diseased Trees

It is possible to treat DED using a private company. If you would like to treat a public tree, you must obtain a free permit. The MPRB will not pay for this service and we do not treat public trees. The permitted company is responsible for pruning and disposal of infected wood that they prescribe as treatment.

Trees that exhibit only slight wilting may be the best candidates for treatment. The treatment is done through injections of a chemical [PDF] at the root flare of the tree.

Private property owners that own a unique or specimen elm are best suited to using this service. We often work with private property owners and halt the removal orders of a condemned elm until a private company can examine the tree and determine if it is a good injection candidate.

Replacement

Replacement Tree

When we remove a boulevard tree, we add it to a replanting list unless something in the environment would prevent the tree from developing properly. It is not necessary to request a boulevard tree replacement. Learn more about boulevard trees and when we replace them in the Trees section

Contact

For additional information, contact the Forestry Department at 612-313-7710 or forestry@minneapolisparks.org.