Connecting people with nature in Ontario's Mississippi Valley

Emerald Ash Borer Preparation

mnr_e002906 emerald ash borer

Mississippi Mills Parks Ash Tree Survey Workshop

by Ken Allison, MVFN

On Wednesday, April 9, 2014, about a dozen members of the Mississippi Valley Field Naturalists gathered at Gemmill Park in Almonte for a refresher on identifying ash trees in the winter. The club has been asked to survey for ash trees in municipal parks in Mississippi Mills to assist the municipality in planning for the expected arrival of Emerald Ash Borer beetles in our community. As it was important to do this survey as soon as possible, surveyors needed to be comfortable with identifying ash trees before they leaf out in the spring.

Brian Anderson, who is with the Mississippi Valley Conservation Authority and serves as County of Lanark Forester, kindly agreed to conduct an open-air workshop for us. We started with a small ash tree that still had fruits hanging on it (see photo below).

ash workshop Allison














Brian Anderson, County Forester, explaining identification tips as the group looks at a small ash in Gemmill Park (photo Ken Allison).

We then walked into the park, identifying ashes of many ages, plus a number of other important forest species, as we went. Particular care was taken to separate ash from maples, as both have opposite branching. During the summer, the two genera are easy to identify by the leaves, but it is not so obvious when all you have are bark and buds to examine. Not all the ash trees were so obliging as to keep some of their keys to make the recognition easier. One thing we learned is that there are a lot of ash trees in Gemmill Park, as in many Lanark County forests.

Brian did a great job as a teacher and the exercise was very worthwhile. The weather cooperated after all the rain the previous day and I think all the participants enjoyed working together.

My thanks to Cliff Bennett for initiating this workshop and to Brian for taking the time to help us out. It was also great to have Calvin Murphy, Recreation Co-ordinator, and Abby Barclay, Environmental Compliance Coordinator for the Town of Mississippi Mills, join us.

For information on the potential impact of Emerald Ash Borer, visit the Ontario Ministry of Natural Resources website:

OMNR: The emerald ash borer, Agrilus planipennis Fairmaire, is an invasive insect species that was first found in North America in June 2002. Shortly after the Detroit, Michigan discovery, forest health monitoring staff from the Ontario Ministry of Natural Resources (OMNR) and Canadian Forest Service (CFS) determined the beetle was also present in Windsor, Ontario. The Canadian Food Inspection Agency (CFIA) was immediately notified. Surveys conducted in Canada and the U.S. found the beetle was well-established in the Detroit and Windsor areas.

Little information was known about the beetle at the time. Arriving in North America through improperly treated wooden packaging material from Asia, the insect didn’t even have a common English name. Despite substantial research and control efforts, the beetle has continued to spread to new areas. Some of this spread has been natural dispersal, but the long distance spread has been helped by people, especially through the movement of nursery stock or infested firewood from infested areas.

Emerald ash borer is now found throughout much of Essex County and part of Chatham-Kent in Ontario. In Michigan, the beetle is concentrated in the southeastern portion of the state, but has also spread to multiple locations in the Lower Peninsula and as far north as the Mackinac Bridge. Spot infestations have also been found in Ohio and Maryland. Researchers, regulators, and urban foresters are in a race to halt the spread of the insect long enough to develop effective control measures to save native ash trees, an important hardwood species in North America.

OMNR: The Threat

  • The emerald ash borer is able to attack and kill healthy trees.
  • All native ash species are at risk.
  • Ash trees of all sizes are susceptible to attack, from 5 cm DBH (diameter at breast height) to 90 cm DBH or greater. Larvae have been found in branches as small as 1.1 cm in diameter.
  • Ash trees are widespread in Canada and the United States, both in natural and urban settings, and green ash is one of the most commonly planted species in the urban forest.
  • Emerald ash borer is very difficult to detect early. When infested trees are found, it’s often 1 year or more after the attack occurred. In addition, there are several other factors affecting ash health in Ontario which may disguise its presence.
  • Estimates show the emerald ash borer has killed several hundred thousand ash trees in Essex County, Ontario, and 8 to 10 million ash trees in southeastern Michigan. Tree loss includes ornamental, rural and woodlot trees.
  • If not effectively controlled, the emerald ash borer is expected to spread across the entire range of ash, causing widespread tree mortality.