The Emerald Ash Borer Threat

The Minneapolis Park and Recreation Board is encouraging residents to take precautions against the spread of Emerald Ash Borer.  If you haven’t heard about this pest yet, the Emerald Ash Borer is an exotic beetle that attacks only ash trees.  The insect has already killed over 40 million ash trees across the country.  A considerable amount of damaged has occurred in southeast Michigan.  If allowed to spread, its effects could be similar to that of the chestnut blight and Dutch elm disease that devastated trees during the 20th Century.

The Emerald Ash Borer was first discovered in Michigan in 2002 and probably arrived in the U.S. on solid wood packing material carried in cargo ships or airplanes originating in its native Asia. The Emerald Ash Borer was found in Ohio in 2003, northern Indiana in 2004, northern Illinois in 2006, and Wisconsin in 2008. It has also been found in parts of Canada, particularly, Windsor, Ontario.

Slowly, the Emerald Ash Borer creeps closer to Minnesota.  The bad news is that it can be spread from region to region somewhat easily.  Something as simple as firewood being transferred from a campsite can be a carrier of a creature that could destroy Minneapolis’ urban forest. More bad news is that there is no known way to cure the disease.  The good news is that the spread of Emerald Ash Borer can be delayed or minimized with assistance from people like you.

If you’ve lived in the state for a day, you know what is at stake here.  Minnesota has the potential to lose 867 million trees because it has one of the nation’s highest volumes of forestland ash on public property.  In Minneapolis alone, 200,000 ash trees make up 20% of all trees on public and private land within the city.

The Emerald Ash Borer kills trees over a period of one to four years. The adult beetles cause little damage as they nibble on leaves. It’s the larvae, the insect’s immature stage, that cause the real damage.  They feed on the inner bark of ash trees, disrupting its ability to transport water and nutrients up the trunk (think of how hard it is to sip through a straw with a hole in it!).  This can cause the tree’s canopy to thin considerably, with many of its branches dying over a short time.

The Emerald Ash Borer adults can’t fly far, so the most likely way that EAB will reach Minnesota is by people moving ash logs, ash firewood or infested ash trees from nurseries. To help slow the spread of EAB Sievert recommends:

• Buying or harvesting your wood near the area where you are going to burn it. If you are buying firewood, ask where it came from. Avoid moving firewood from its area of origination. Especially avoid bringing wood into Minnesota from out of state. In Minneapolis, firewood dealers are required to be licensed by the City, so ask firewood peddlers for their City license.

• Watching ash trees carefully for tree canopy thinning or small “D” shaped exit holes left in the bark by Emerald Ash Borers. The earlier they are found, the sooner they can be addressed.

• If there is any suspicion that a tree is infested with Emerald Ash Borer, residents can contact the MPRB at 612-370-4900, or the Minnesota Department of Agriculture’s "Arrest the Pest" Hotline at 651-201-6684; 1-888-545-6684 for Greater Minnesota.

Learn more about Minneapolis’ urban forest.

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