Can You Save Your Ash Trees From the Emerald Ash Borer?

The emerald ash borer has invaded Canada and it’s not going away anytime soon. This jade green jewel beetle is native to northeast Asia and since its arrival in North America in the 90’s,has been feasting on our local ash trees. In northeast Asia, the emerald ash borer doesn’t do significant damage to the indigenous trees but with no natural predators in Canada, this little bug is rapidly destroying our native ash forests.

The threat posed by the emerald ash borer is that the larvae feeds on the cambial layer below the bark of the tree and disrupts the flow of nutrients, sugar, and water throughout the tree. The tree will slowly die and after about two years your beautiful ash will be dead. The EAB has killed approximately 15 million ash trees in Canada since it was first detected almost two decades ago.
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If the emerald ash borer continues to spread unabated, it poses a major economic threat, but that does not mean you have to cut down all your ash trees at the first sign of trouble. In fact, when dealing with emerald ash borer, you should not remove or do any tree pruning until late fall because the borer is most active during the summer and cutting down infected trees will only speed up the spread of the EAB. But cutting down trees in fall when the emerald ash borer is less active will limit the spread of the insects.

If you have a few ash trees in your garden or a couple of large shade trees and are worried about them being attacked by emerald ash borer, you do have a number of options. Preventive treatments are the most effective in the fight against EAB but if you detect an infestation early, you might be able to treat your tree and prevent further damage, giving the tree a chance to recover and ultimately survive.

One preventive treatment is a drench that you can apply to your trees, but it is only effective on smaller trees with a trunk diameter of less than 8 inches and the treatment is expensive. Another emerald ash borer treatment that can potentially keep your trees alive are injections that are administered by a professional arborist. The trees will have to receive these injections for as long as they are alive but saving a whole lot of trees in this way, however, is not economically viable.
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Insecticide treatments for emerald ash borer are not needed for ash trees that are further than 15 miles from a confirmed EAB infested site. Even within the 15-mile radius, not all ash trees can be treated with insecticide because it is expensive, and this form of treatment is typically only used for high-value trees. High-value ash trees are generally healthy trees that add to the value of your property, play an integral role in your landscaping, reduce your energy costs by shading your home or provide environmental benefits.

​There are a number of symptoms signs of EAB that you need to be on the lookout for. These include thinning of the tree canopy, splitting bark, woodpecker damage, and epicormic sprouting along the trunk. All these symptoms are signs of a tree under stress and this can be an indication of emerald ash borer or some other disease. Other signs of emerald ash borer activity include D-shaped holes in the bark and S-shaped larval tunnels under the bark.

Emerald ash borer can only naturally spread a few kilometres a year, but it is easily concealed in the bark of trees, logs, wood chips or timber products and rapidly dispersed throughout the country by irresponsible or uninformed people. If you remove a tree infected by emerald ash borer you need to get rid of the wood in a responsible manner and not transport it anywhere. You can contact your local municipality to see if they have a wood disposal program. If you have your tree removed by professional tree removal service, like Martin’s Tree Service, they will be able to advise you on how to deal with the wood.