The Toronto Star today contained this article about the sad and coming total demise of the city’s ash tree population over the next ten years. It’s all thanks – or no thanks, depending on your perspective – to the beautiful but deadly emerald ash borer.
Through a tree course I took at Ryerson some years ago with local expert Sam Benvie (see his Encyclopedia of North American Trees), I’d only recently come to appreciate the ash – particularly the white or American ash, Fraxinus americana. It’s pictured here in its fall glory, a rich gold overlaid with mahogany or plum. Its cousin, the green ash, Fraxinus pennsylvanica, is more modest in its fall colour: the gold has to suffice.
Both of these native North Americans are equally susceptible to the emerald ash borer, whose tunnelling habit beneath the bark is undetectable until the tree is dying.
Apparently, this is happening to such a degree that the arborists are virtually throwing up their hands in defeat, and collecting and saving seeds to reintroduce the ash once the insect infestation has run its course.
Incredibly, according to my web search, this pest was only noted as a serious problem about two years ago. The emerald ash borer, an irridescent green beetle, is native to Asia. The ash population has no defense. [Update: Here’s a fact sheet from Natural Resources Canada, from whence came the image at left.]
The stretch of Coxwell Avenue near our gardens is a monoculture of stately ash street trees. It will be a sorry thing to see them go.