Halifax Tree Project

Are our Halifax Ash Trees Doomed?

Peter Duinker, Halifax Tree Project, 2025-06-29

Meanwhile, if one looked at the hills of Bedford while driving the Bedford Highway, one could begin to see, year by year, more dead ash trees in the treed skyline. In 2022, HRM’s urban forester and I found an infected ash tree next to Uplands Park (along Hammonds Plains Road). A colleague living in Clayton Park said that ash trees in her neighbourhood were infected. The Canadian Food Inspection Agency (CFIA) was reporting more trees around HRM also infected.

In the winter, it is difficult to pick out dead and dying ash trees in HRM because no broadleaf trees have green leaves. However, in the past six weeks or so in the city, I have been scanning the tree canopy for evidence of dead and dying ash trees. To my horror and dismay, I am seeing them pretty much everywhere, on and off the Halifax Peninsula. I got a call from a resident of the North End who was wondering what might be wrong with the big ash tree in the back yard – it was not leafing out at all. I paid a visit immediately and, while I could not see any of the tell-tale D-holes in the bark, I pushed on the bark with my thumbs and it felt spongy. I tried to tear a bit of bark away, if indeed it would release. Well, it released and revealed the larval galleries in abundance. The tree had just died over the winter from EAB!

So, during the past month, whenever walking or cycling around the Peninsula, I have been looking for signs of infected ash trees, mostly the thinning of the canopy and sometimes the complete lack of foliage. They are everywhere! Here are a two photos.

What can be done about this tragedy? When trees are at the stage shown in the photos, nothing but removal. I feel for the property owners who will have to pay out the many hundreds, perhaps a few thousands, of dollars to complete that removal. But then there is the prospect of treatment of yet-uninfected trees. This too is costly, but, depending on the importance of the tree, may well be worth it. I have identified three ash trees I think should be saved, or at least have their lives prolonged a bit, with a chemical treatment. One such tree is in Uplands Park (pictured below). Another is at the corner of Quinpool Rd. and Monastery Lane. The third is a fascinating ash tree in Dalhousie’s stone fence at the corner of Coburg Rd. and LeMarchant St. It would be such a shame to lose these trees, and I recommend treatment.

EAB is a contemporary example of pest organisms making their way around the globe, inadvertently, in infected woody materials. Here are some other examples. Chestnut blight (a fungus native to Asia) came to North America in the early 1900s and has devastated the populations of sweet chestnut (not horse chestnut) across the USA and Canada. Beech bark disease is alleged to have arrived in Halifax on infected beech planting stock from Britain around the 1890s. The European beech has resistance but the American beech, by and large, does not. I have seen this disease on American beeches even west of Toronto.

Dutch elm disease came to North America in infected lumber from Europe in the mid-20th century. Fortunately, Halifax has been spared any widespread damage to its elm population (no-one knows why), but many towns in Nova Scotia, and in rural and urban ecosystems all the way to Winnipeg, have not been spared. I recall, as a youth in central Ontario in the early 1970s, cutting dead and dying elms out of woodlots to try to slow down the elm devastation.

Hemlock woolly adelgid has found its way to Nova Scotia in the past decade or so, allegedly on birds flying here from New England. First detections were deep in the southwest of the province, and it is moving east. It is said to be native to Asia and the Pacific Northwest of the USA. It has not had devastating effects on western hemlock populations in Canada, but it sure is killing eastern hemlocks here.

Unfortunately, the list goes on. The Japanese beetle that so many Halifax property owners are trying to fight came here, at first detection, in 1939. That beetle seems to feed on just about anything green. The brown spruce longhorn beetle, responsible for the death of numerous red spruces in Point Pleasant Park, doubtless arrived here on infected wood at the container terminal in Halifax’s south end, probably in the 1980s.

We can find numerous other examples elsewhere. I just now wondered if oak processionary moth has been found in Canada. It hasn’t, but the news is that it arrived in Britain in 2005 on infected planting stock from eastern Europe.

What are we to take from all the bad news associated with insect and disease pests from other parts of the world finding their way to Nova Scotia? I have two major reflections:

1_ Most of the movement of such pests from elsewhere to here happens on account of people moving woody materials such as packaging, pallets, and planting stock. The moving of such materials is one thing we can control, but the other thing is the potential for phytosanitation. What especially grates me is the movement of infected planting stock – our phytosanitary standards for accepting foreign planting stock need to be strictly enforced (and perhaps even updated).

Connected to this, though, is our own behaviour locally and interprovincially. While it is not illegal to move firewood from one campground to another, nor to transport it across provincial boundaries, it is highly frowned upon by provincial and the federal governments. So please, consume ONLY local firewood in all your wood-burning applications.

2_ We have no ability to predict what will be the next few introductions of invasive alien species that may jeopardize our local trees. In much of eastern Canada, we loaded the streets with American elms in the first half of the 20th century and then lost so many of them to Dutch elm disease. Then we loaded the streets with various ash species, only to lose most of them in the past two decades to EAB. We seem to have learned our lesson, finally, and now are not favouring only one or two species for our street-tree plantings but trying to have a strong diversity.

In conclusion, our urban trees are far too precious for us to be flippant about invasive alien species, particularly insects and fungi. Let’s all do what we can, in our own small way, to prevent their movement, first of all, and then prevent their spread if we find them here. Get professional help – just like you would for health questions, auto repair, and financial affairs – to deal with any suspected infestations. Good luck!