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Control of Emerald Ash Borer and Elm Disease

Posted On Tuesday July 27, 2021

Many of our residents have noticed that we have cut down many trees in our parks over the past two year. Trust us, we don't cut trees unless we have to. These trees had Ash and Elm disease and must be removed immediately. Don't worry, we have plans to replant some healthy native species in the fall!

What is the Emerald Ash Borer?

The emerald ash borer (Agrilus planipennis) is a species of metallic wood-boring beetle native to East Asia, including China and the Russian Far East. Most species of North American ash trees are very vulnerable to this beetle, which has killed millions of trees in Canada in forested and urban areas. No North American natural predators, such as woodpeckers, other insects or parasites have been able to slow the spread of the emerald ash borer or keep trees from being killed by it.

Up to 99% of all ash trees are killed within 8-10 years once the beetle arrives in an area. Adults can fly and spread locally. The moving of infested material causes long distance spread as does adult beetles hitchhiking on vehicles.

Impact of Emerald Ash Borer

  • After an infestation remaining beetles can kill new growth, jeopardizing forest recovery.
  • In urban areas, infestations have killed tens of thousands of ash trees planted in parks and along streets.
  • Municipal governments are responsible for removing dead ash trees on urban land. Ash trees that are affected should be chemically treated or removed and replaced, which can be a significant economic burden.
  • Losing urban canopy can increase homeowner heating/cooling costs and can affect people with health issues such as respiratory illnesses.

What is the Elm Disease?

Dutch elm disease is caused by two related microscopic fungi: Ophiostoma ulmi (Buisman) Nannf. and Ophiostoma novo-ulmi Brasier, the more virulent. The fungus develops in the sap conducting vessels. The first symptoms of the disease usually appear between mid-June and mid-July. Leaves on one or more branches wilt, curl, dry out and turn yellowish or brownish, usually without falling off. The disease is transmitted by insects of the bark beetle group.

Impact of Dutch Elm Disease

The affected parts of the tree wither and die more or less quickly due to lack of sap Elm trees may survive for a few years, but some die within a year of infection. There are three native species of elm in Canada and all have been affected to varying degrees by Dutch elm disease. The greatest impact has been on American Elm (Ulmus americana) and Rock Elm (Ulmus thomasii). Red or Slippery Elm (Ulmus rubra) is least affected by the disease

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