Elms Need Protection from Dutch Elm Disease

By: Jean Ferdinandsen, Certified Arborist WI-0149A

Spring 2007 Newsletter in Adobe PDF format Susceptible elms (American, red and rock) can be protected from Dutch Elm Disease with macro-infusions of Arbotect fungicide every two or three years.

When people talk about trees, many have a story of a great yard elm or an elm-lined street that was cut down. Ask those same people if they are aware we can now save elms and they get a look of sorrow, anger, bewilderment or even disbelief. Amazing the effect trees have on us!

You can save susceptible elms by protecting them from getting DED (Dutch elm disease). To do this, the elm should not already have DED. It is helpful if the tree is in good health and the root zone must be isolated from other unprotected elms. Ask a Wachtel Certified Arborist to qualify an elm for protection.

What is DED and how does it spread? DED is a fungal disease that causes the water-conducting tissues of the tree to plug up, thus causing the tree to wilt and die. The disease can take a few weeks to over a year to kill the tree. Elm bark beetles pick up the fungus from breeding sites in infected elms. Beetles then fly off to feed on the two- to four-year-old twigs of healthy trees, infecting them with fungal spores. That is why sanitation (removal of any diseased elm wood) is so very important to keep the disease from spreading. Wachtel does not leave any infected elm wood on job sites. We recommend that elms be regularly deadwood pruned to make them less attractive to breeding beetles.

DED may also spread through root grafts from nearby infected elm trees. When this happens, there is no hope of saving the tree. It is important to note, fungicide treatments do not provide protection against the spread of DED through root grafts. Your Wachtel Arborist will recommend breaking root grafts or removal of unwanted elms that are possibly root grafted.

Susceptible elms can be protected by macroinjection of Arbotect fungicide which is the most proven and effective protection from DED. Macro-injections allow us to deliver high volumes of fungicide-water mix throughout the crown. This is important to protect the elm from DED transmitted by feeding beetles. Arbotect then moves into new sapwood in succeeding years. The tree will need to be injected again every two (for very large trees) or three growing seasons.

Can an infected elm be saved? If the infection is found early and has not spread far, it is possible to cut out the infection with a procedure called tracing. When tracing, the result looks much like a lightning strike, from which the tree can recover. If no symptoms reappear, the tree will need to be protected from future DED.

What to look for to spot DED early: Property owners can easily inspect their trees. “Flagging” is an early symptom of DED where leaves on branch tips turn dull green to yellow, curl, become dry, and start to drop off.

If you want to protect an elm, or if you have an elm you think might be infected, be sure to contact your Wachtel Certified Arborist as soon as possible. We can help save these great trees for future generations to enjoy!

© Copyright 2007 – Wachtel Tree Science & Service, Inc.

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