Winnipeg trees won't be wrapped this year to protect from cankerworms
Trees Winnipeg says the Emerald ash borer poses a more pressing threat to the city's trees

cbc.ca
Sept. 2, 2015

For the first time in 15 years, Winnipeg trees will be left without the familiar band on their bark to protect them from cankerworms.

Trees Winnipeg, a non-profit organization, has been wrapping roughly 8,000  of the city's trees each year to protect them from the pests but this year the group is prioritizing the battle against the invasive Emerald ash borer.

"So even though cankerworm populations can be quite destructive, we know the population is cyclic and the trees can respond. To other species like Emerald ash borer, the trees have no immunity. So those are actually going to be a huge threat," said Kerienne La France, the executive director of Trees Winnipeg.

Cankerworms are known to chew holes in the leaves of elm, ash, Manitoba maple, linden, oak and ornamental trees. In particularly bad years, trees will be completely stripped of their leaves after being overwhelmed by the worms.

La France said the city spraying program meant to fend off forest tent caterpillars should also help to keep cankerworm numbers down.

The tree banding program was pursued because the bands keep the wingless adult female cankerworms from laying their eggs in the crown of the tree in the fall and spring.

The bands are made from insulation and plastic and are covered in a sticky substance called Tanglefoot. The adult cankerworm must climb the tree to lay eggs but get stuck in the Tanglefoot when they cross the band.