Elm trees turning over a new leaf in Toronto

In the 1960s most of the city's elm trees were killed by Dutch elm disease — now they're making a comeback

CBC.ca
Aug. 8, 2016

Near Leslie Street and Highway 401, cars rush past a stand of trees: evergreens, maples … and a four year old elm tree.

It's a native species that is making a resurgence, part of a concerted effort by the city of Toronto to reintroduce elms as a measure to maintain the health of the tree canopy. Toronto plants an average of 100,000 trees and shrubs each year; of those about 6,000 occur through the residential tree replacement program.

In the 1960s, about 80 per cent of the city's elm trees were killed by an outbreak of Dutch elm disease — a fungus that blocked the tree's water conducting system.

But thanks to new hybrid varieties, elms are making a comeback.

Ray Vendrig is with the city's forestry department. "We haven't planted elms in the city for a number of years," he told CBC News, "but nurseries in the United States and Canada have been working on developing new hybrid elms … so the city of Toronto and a number of other municipalities have been planting other varieties.

"We're trying different ones, but they're all proving to be very good," he added.

Vendrig says these new elms are thriving and can tolerate more than disease.

"They've proven to be fantastic trees. They grow quickly, they have a great root system and they're able to withstand the urban conditions like poor quality soils and droughts like [this summer's]."

Expect to see more of them: Vendrig says these new elms are one of the top five tree species that the city is planting.

"We do try to plant a diversity of species whenever we plant on any street in any neighbourhood, but in certain conditions — like on major arterial roads, where the tree may not get watered, and it's not in front of somebody's house and you get a lot of salt spray — conditions there might be little more severe, but these trees seem to do very well in those conditions."

With their spade-shaped green leaves and rough coarse bark, mature elms can reach as high as 35 metres. Verdig says Morton, Accolades and Valley Ford Elms are being planted across the city.

Residents can help those elms, and the rest of the city's trees, flourish, Verdig adds, especially in the hot, dry summer. And if you're already out watering your lawn, he says, "Help us water those trees."