The death knell has been sounded for Winnipeg's ash trees, due to the emerald ash borer — all that's left to do now is preserve the ones that are left as long as possible.
To that end, the city's insect control branch will begin Monday the second consecutive year of its EAB management program. It is designed to slow the destructive path of the wood-boring invasive species, which have been plaguing the ash tree population since first being spotted in Winnipeg in 2017.
The program, costing $225,000, involves injections of insecticide (TreeAzin or IMA-jet) into the trunks of still-healthy ash trees located on city property to kill any EAB larvae inside.
"Our emerald ash borer program involves a combination of monitoring, pro-active tree removals, tree planting and also injection treatments. Last year, we injected over 1,000 trees as part of our program, and this year we will be injection an additional 1,000 trees," said Kerienne La France, urban forestry technical services supervisor.
She said about 1,200 ash trees have already been removed this year due to EAB damage. About 100,000 ash trees are located on city property, with another 250,000 on private property.
While city officials say "it is inevitable" the ash tree portion of the urban canopy will be wiped out in the next decade by the bark-munching beetles — they can't be eradicated once they have invaded an area — the treatments can protect trees for up to two years.
Manitobans can help slow the EAB invasion by not moving firewood, La France said. "Invasive species can hitch hike on firewood piles, so we would like people to know to wait to buy firewood until you get to your destination, and then burn it all or leave it behind when you come home."
The worm-like larvae kill trees by feeding on the inner bark, creating S-shaped tracks, called galleries, as they move around a tree's trunk. The galleries interfere with the flow of water and nutrients, causing the tree to die in one to three years.
Adult beetles are metallic green, 8.5- to 14-millimetres long, and leave a D-shaped exit hole in the bark.
"It is a significant concern. We are doing as much as we can with the resources we have available, and we're implementing all of the tools available to us," La France said.
Residents with ash trees on private property are encouraged to contact an arborist, who can help them develop a plan to try to protect the trees for as long as possible.
"People can keep an eye out for any suspicious ash trees that seem to be declining in health, especially if they have extensive woodpecker damage," La France said, noting woodpeckers feed on the EAB larvae.
Ash trees on city property will be treated Monday through Friday, 6:30 a.m. to 2:30 p.m., until late July. A yellow sign will be placed in front of trees selected by the urban forestry department for treatment.
Updated on Friday, June 14, 2019 at 6:11 PM CDT: Treatments can protect trees for up to two years.