Green dots goooood; orange dots, baaaaad.

What the heck are those green dots? I wondered, as I walked up Coxwell Avenue the other day. They were painted on most of the towering ash trees (Fraxinus spp.) that line this stretch of road. Oh no. Have they run out of orange paint, and are they coming down?

Relax, Helen, Google said. It’s a sign that these trees are being treated to deter the invasion of Emerald Ash Borer (EAB). The City is trying to save them. Good news, for once. Hooray!

Here are the details from an August article by Mike Adler in the Etobicoke Guardian, published on InsideToronto.com:

City contractors injected 4,000 trees with TreeAzin last summer and are treating 9,000 more this year – ash along streets or in parks selected, ward by ward, for being in good condition and not showing a lot of the leaf dieback that first marks the infestation’s effects.

At eye level, contractors staple small green aluminum plates on the injected trees, a sign of the city’s commitment to keep injecting them every two years until the pest is gone.

TreeAzin is a neem-based systemic insecticide (but not neem oil) that is injected under the bark and kills EAB larvae by disrupting their moulting cycle. Females feeding on the leaves of treated trees can also become less fertile. The only trees being treated by the City are street trees or trees on City land. If you have private ash trees, it’s up to you to try to treat them. Get more info here.

By coincidence, the City arborist quoted in the article above is Jozef Ric, who spoke to me about wood wasps in this post back in 2009. Unfortunately, the sugar maple I was writing about was removed the year after. Let’s hope for a happier ending for our local ash trees.

The green dot and the metal tag are signs these ash trees are being treated to prevent infestation by EAB.