Dutch elm removal reaches ‘critical point’ as city confronts backlog of diseased trees, city forester says.
By Bryce Hoye, CBC News
There are more trees marked for death right now than Winnipeg has seen since the mid-1990s, and the city’s forester says the backlog of infected elms is helping Dutch elm disease spread.
“Basically we just don’t have enough resources to keep up with these high numbers,” Martha Barwinsky said.
“We’ve reached a critical point in the management of Dutch elm now, and definitely we need to get this backlog dealt with.”
At about 230,000 individual trees, Winnipeg is home to the largest population of American elms in North America.
The city’s forestry branch estimates there will be 8,321 trees tagged with those ominous orange dots by Sept. 30 — including 821 that were marked in 2015 and 2016 and still haven’t been cut down.
The forestry branch was alotted $4.28 million dollars to fight Dutch elm this year. Barwinsky says the annual budget usually allows for the removal of about 3,500 elms per year, which is why the forestry branch recently applied for additional funding.
Last week, the city’s standing policy committee approved a proposal to direct $380,000 from the forestry branch capital budget toward the Dutch elm removal program for the remainder of the year. The extra funds will help the city take out 447 additional diseased elms, bringing the estimated number of trees removed this year to 6,547. (The removal season ends on Sept. 30.)
Even with the extra funds, the branch is projecting to overspend by $680,000 by the end of this fiscal year and still won’t totally get the city caught up on the trees waiting to be removed previous years.
“We need to stop the spread, we need to clean up that backlog and then we need to get the currently marked trees out in a timely manner,” Barwinsky said.
‘Lose a sense of place’
Retired CBC broadcaster John Drabble said he thinks the problem is going to get worse before it gets better.
At this rate, he fears future removal costs could overrun the city, and he worries more of the expenses could get passed on to homeowners.
This month Drabble watched city crews tag 10 elms and haul away several others from his and neighbouring lawns in the Kingston Crescent area of St. Vital.
“Our tree looked fairly healthy but they said it was diseased, and my feeling was they might as well let it go now while the city crew is here than wait for it to die,” he said.
“These trees were planted before this house was built.”
Boulevards and lawns in the riverside neighbourhood are lined with elms, but the canopy is getting thinner every year, Drabble said.
“You had a concept of what your neighbourhood was like in your mind. Now it’s completely changed,” he said. “It’s a bit disorienting in a way. You just lose a sense of place.”
Monocultures at risk
The hardest hit areas are often parks and boulevards, where the city planted its monoculture of elms decades before the disease arrived in Winnipeg in 1975.
A moratirum was placed on planting elms after the disease arrived, so the city set off planting another monoculture, this time of ash trees.
The problem is that when you plant a bunch of one species in an area the trees become more susceptible to disease, which is why elm-heavy areas such as the West End, Wolseley and River Heights are among the worst areas for infected elms, Barwinsky said.
The city has been planting a more diverse stock of species in the past decade as a future safeguard, and working with local tree nurseries to do the same. But that diversity might not provide much of a shield when emerald ash borer beetles invade — and they are coming, Barwinsky said.
The Asian beetle has been observed as near as Thunder Bay and Minnesota in recent years.
“We are no longer planting ash trees at this time as we prepare for the incoming emerald ash borer,” Barwinsky said. “It will be a significant loss of our canopy.
“With emerald ash, we know that there will be significant losses and we are just managing mortality. With the elms, we know that we can preserve them.”
Early ID system
The city partnered with a team of students and researchers this summer to develop a more precise way of identifying brood trees earlier in the cycle of infection. It’s still early days and they’re only now starting to pour over the data collected this year, Barwinsky said.
The city played an advisory role in a previous five-year study by the University of Manitoba and what was then Manitoba Conservation. The rapid removal effort set out to identify infected trees and remove them the same year in a handful of neighbourhoods.
They found new generations of elm bark beetles, which carry the disease from tree to tree, take flight at the end of summer. The team managed to cut elm infection rates in half by identifying brood trees and destroying them before the beetles emerged en masse and spread the fungus to other trees, Barwinsky said.
But due to funding restrictions, it’s been next to impossible to replicate that method on a mass scale.
“Realistically here with so many thousands of trees, we can’t really have a true rapid removal program, but we could have a modified form of that program where we could reduce the insidence of disease,” Barwinsky said.
Don’t burn diseased elms
City crews and contractors are monitored to ensure tools are sterilized regularly so they don’t unwittingly spread the disease from tree to tree, Barwinsky said.
But there are things residents can do to stem the spread.
The city has already found 300 log piles in yards this year that contained elm, Barwinsky said.
“In the past we’ve actually seen outbreaks of Dutch elm disease in an area where there has been an elm firewood pile that hasn’t been disposed of,” she said, encouraging Winnipeggers to report suspicious firewood or log piles to 311.
“Be wary of where this firewood is coming from.”