Dutch Elm Disease

Protection

What can I do if my tree is already infected?

Most infected elms cannot be saved. In rare cases, if the fungus has not moved into the root system, physically cutting out the infected portions of the tree, with a process called tracing, can save the elm.

Sanitation

Sanitation is the most important tool for controlling Dutch Elm Disease on a community-wide basis. It involves identification and removal of diseased elms. Such practices eliminate beetle breeding sites and reduce the number of disease carrying beetles.

How can I protect my Elm tree?

The goal when protecting elms from the Dutch Elm Disease fungus is to evenly and completely distribute a fungicide chemical throughout the entire canopy of the tree.

• To protect a tree from beetle-transmitted fungal infection, Arbotect (an EPA registered fungicide), must be evenly and completely distributed throughout the 2-4 year old branches.
• The only way to get even distribution is by macro-infusion of a large volume of solution into the root flares of the tree.
• Arbotect is a fungicide that protects elms from beetle-transmitted infection, and is the only fungicide that provides three growing seasons of protection.
• Arbotect does not protect elms from root graft infection.

Scientifically proven and field tested

Arbotect has been shown through research to be effective for the protection of elms from Dutch Elm Disease by the University of Minnesota and the State University of New York. Arbotect alone has the unique ability to move into newly formed sapwood, while resisting degradation resulting from cold, heat, and other adverse conditions. More arborists and tree care companies across the United States reach for Arbortect fungicide, in the battle against Dutch Elm Disease, than any other product. It keeps saving elms year after year. Nothing else comes close.

The Basic Facts

What is the cause of Dutch Elm Disease

Dutch Elm Disease is caused by an aggressive fungus (Ophiostoma-ulmi) that kills elms regardless of their health. It is considered the most costly shade tree disease ever and will remain active in a community as long as there are susceptible trees. The fungus invades the water transporting vessels and produces toxins to which the tree reacts. In defense to the toxins the tree produces gums and internal growths designed to block the advance of the fungus. The combination of the toxins and the defense mechanisms of the tree inhibit water flow to the crown, which causes wilting and tree death.

How does Dutch Elm Disease spread?

Female elm bark beetles lay their eggs beneath the bark of dead and dying elm trees. If the elm is infected with Dutch Elm Disease the newly hatched beetles will emerge from the tree carrying the deadly fungus on their bodies. The beetles fly to healthy trees to feed on 2-4 year old branches and thereby spread the disease.

• 2-3 generations of elm bark beetles hatch each year
• Thousands of beetles may hatch from a single tree

Besides beetle transmission, Dutch Elm Disease may also spread through grafted roots. When elms grow in close proximity to each other, their roots can come into contact and graft together. This common root system provides the fungus with a pathway to spread through an entire stand of healthy elms very quickly.

What are the symptoms of Dutch Elm Disease?

Dutch Elm Disease symptoms begin to develop 4-6 weeks after infection. The first noticeable symptom that results from the fungal occupation of the water conducting vessels is wilting or “flagging” of one or more branches, usually starting at the branch tip. Leaves on infected branches turn dull green to yellow, curl, and become dry and brittle. As the infection spreads the wood beneath the bark displays a brown discoloration.

Management and Research

Cities such as Minneapolis, Edina, Richfield, Minnetonka, St. Louis Park and Bloomington are still home to large inventories of American elm trees. In fact, the Twin Cities boasts one of the largest American elm populations in the country.

For approximately 50 years Dutch Elm disease has devastated unprotected elm populations across the United States, spreading westward from its origins on the East Coast. However, with the development of responsive community programs and effective fungicidal injection treatments, the disease has been brought under reasonable control. But it never really went away.

Dutch elm disease kills elms regardless of their health. It is considered the most costly shade tree disease ever and will remain active in a community as long as there are susceptible trees.

To properly manage Dutch elm disease, four steps are generally required.

1. Identify the disease by the "flagging", or wilting of leaves typically located at the ends of isolated branches in the canopy. The disease moves down the limb and then into the main stem.
2. Remove infected branches from trees (if identified in time) or remove entire trees, immediately, in order to halt further spread of the disease throughout the neighborhood.
3. Isolate infected trees from nearby healthy trees by soil trenching, which prevents spread of the disease via root grafting.
4. Protect valuable remaining elms with the use of an approved Dutch Elm disease fungicide such as Arbotect 20-S.

Read from other sources, including university studies and practitioner testimonials, why Arbotect fungicide is the proven, best choice for protecting trees from Dutch Elm disease:

• North Dakota State University (see 'Chemical Treatment' section)
• University of Minnesota (see 'Elm, American' section)
• Virginia Polytechnic Institute and State University (see pgs. 65, 75, 76, 77, 87, 90, 109, 110)
• Elm Loss Comparison of Arbotect and Alamo - Swingle Tree Co.
  Elm Preservation Newsletter - Swingle Tree Co.
  Swingle Tree's Experience
  Swingle of Denver, an Outstanding Treecare Company
• Wachtel Tree's Experience
  Wachtel Tree Science & Service - The Leading Tree Company Serving Milwaukee

Rainbow Treecare is the leading tree care company in the United States that protects elms. Contact us to make a plan to protect your trees.