City gaining little ground in fight against insects

Trees not being replaced as quickly as lost, says City forester


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This article was published 31/05/2019 (1400 days ago), so information in it may no longer be current.

Residents in Riverview and central River Heights will feel the heat this summer thanks to a thinner canopy of boulevard trees and a relentless invasive insect.

City of Winnipeg forester Martha Barwinsky said her crews are nearly finished removing 700 black ash, and some green ash, trees from those neighbourhoods. The 700 trees fell victim to the cottony ash psyllid, or jumping tree lice, and were either dead or near death at the time of the removal.

“It’s very significant for the people that are living on those streets. Because of the monoculture, they’re seeing a clear-cut on their boulevard,” Barwinsky said.

The invasive tree lice was first discovered in the Forks area about two years ago.

According to the province of Manitoba, jumping tree lice lay their eggs in trees which hatch in the spring.

The nymphs feed on growing leaves and suck out sap, causing leaves to curl and produce a white “cottony” substance. In July, the adult bugs lay eggs which hatch in August and continue to feed on the curled leaves. Over time, the approximately three-millimetre bugs weaken ash trees making them vulnerable to illness and premature death.

Since their discovery, Barwinsky said the number of insects has increased and they are found in varying quantities across the city.

Riverview and central River Heights, however, proved to be an ideal habitat for the insect.

“Those were streets that were primarily lined with black ash. It was a monoculture situation on those streets and there was a real dense habitat for that pest,” Barwinsky said.

“We also over the past couple of years, have experienced very hot, dry summers and so the trees have been under greater stress, and at the same time those pests tend to thrive in those kind of conditions.

“It was the perfect storm.” 

She said it won’t be until mid-June when other potential jumping tree lice outbreaks will be evident.

“Our insect control branch is surveying here and there, and we’re watching all the time,” Barwinsky said. “We’re relying on residents phoning in if they notice there is a problem with their boulevard trees, to call 311.

“We expect we will see more outbreaks this summer because the population of the pest has been building.”

Combined with another invasive species, the emerald ash borer beetle, Winnipeg is projected to lose its entire population of ash trees over the next 20 years, Barwinsky said. Last year 1,400 ash trees were cut down and 9,000 elms came down due to Dutch elm disease (DED) and general mortality. Barwinsky said the City has caught up with its DED removals and crews will be monitoring for elm wood on properties this summer, which must be disposed of at the landfill.

So far, 15 trees have been identified for emerald ash borer and removed. Larval galleries have been found in a tree on the riverbank in the Archwood neighbourhood, and Barwinsky said they believe the beetle is “dispersing.” The City is monitoring ash trees across the Winnipeg and 200 traps have been installed.

While many trees have come down, Barwinsky said the number of new trees being planted is not sufficient. Just 2,580 trees were planted by the City of Winnipeg in 2018. This year, the City is on track to plant 2,000 trees. It costs the City about $740 to plant and maintain a single new tree for two years.

It will be at least two years before the trees in Riverview and River Heights are replaced.

“I often say that our canopy is shrinking because we aren’t replacing the trees that we are removing,” she said.

In Crescentwood, a group of neighbours decided to lend a hand to the City’s reforesting efforts. Earlier this year, the Friends of Peanut Park, an advocacy group for Enderton Park, successfully applied to City Centre community committee for a $12,000 land dedication reserve grant.

Working with the urban forestry branch and a City of Winnipeg approved landscaper, the group planted 70 15-gallon trees on boulevards in Crescentwood. Many of the existing trees in the area are either ash or elm.

“We had a ready-to-go group and we said, well ‘We’d like to do something for the trees on the boulevard,” said Charles Feaver, chair of the Friends of Peanut Park tree committee. “We decided we didn’t want to cut down trees, which would also be helpful, because neighbours would hate it… so we said instead we’ll plant trees.”

Between 25 and 30 neighbours in the area are responsible for the watering and care of the 70 new trees, which were planted by the landscaper. Varieties include silver cloud maple, linden, delta hackberry, and Russian mountain ash. Feaver said an additional 32 trees were planted on private property as part of the initiative.

“It’s been a lot of fun in the neighbourhood,” he said. “There’s really strong support for this.”

The initiative is a pilot project and Barwinsky said they’ll be evaluating the effectiveness to determine whether to continue the program in other areas in the future.

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