In recent years, a very serious new pest has been discovered in the GTA. The Emerald Ash Borer is a non-native, small green beetle that feeds on woodland and landscape Ash trees. The beetle has no known natural enemies in North America and limited treatment options exist.

The Emerald Ash Borer (EAB) is a native beetle of East Asia. It was first found in Ontario in 2002, in Windsor. All 16 species of Ash (Fraxinus spp.) found in North America are susceptible to the EAB, regardless of age and stage of development. The Emerald Ash Borer can kill healthy Ash trees in only one to two years when infestations of its larvae are severe. The larvae create tunnels when they feed under the bark of trees and prevent nutrients from travelling down from the leaves. This pest is well suited to Ontario’s climate; it spends the winter under the tree bark where the temperature is warmer than the atmosphere.

Currently there are two options to consider for the Ash trees on your property; treat the tree or remove the tree.

Treat the tree

Ash that are in good health, structurally sound, in a prominent location on the property etc. can be treated. TreeAzin, a natural systemic insecticide, is an organic pesticide registered by Health Canada’s Pest Management Regulatory Agency. The pesticide targets the insect in two ways:

  • Once injected into the tree the liquid moves through the tissue and into the leaves. The larvae of the insect are killed when feeding on the tree’s tissues by regulating growth and disrupting normal molting.
  • The insects fertility and egg viability is reduced when adult females feed on the tree’s foliage.
  • Each tree on the property should be assessed individually and cost is variable based on the size of the tree. Treatment is conducted on a bi-annual basis. Leading consultants are predicting at this time that the population will persist at high levels for the next 10-15 years and then decline. When budgeting for treatment, 5-8 applications must be considered.

Remove the tree

Ash that are small, hazardous, in declining health would be strong candidates for removal. In some cases, the cost of removal will be less than that of treatment over the abovementioned timeframe. However, the cost of removal is a larger sum due upon completion of the work. If you have many Ash on your property you may want to select some for treatment and some for removal. Cost of removal will vary based on size of the tree and complexity of the removal.

Research on the Emerald Ash Borer and its control methods is continuing. Predator species have been released in the States and could be released here in the near future. Unfortunately the effects of infestation do not facilitate much reaction time. The Ash on your property should be inspected and a plan developed to help minimize the urgency and burden this pest will cause in the coming years.


Government of Manitoba. Forestry Branch: Emerald Ash Borer in Manitoba. Accessed 8 July, 2011

Maryland Department of Natural Resources. Emerald Ash Borer. Accessed 8 July, 2011

University of Illinois. Illinois Natural History Institute. 2011. Accessed 8 July, 2011

BioForest Technologies Inc. Accessed April 2, 2013.