On Monday, the city launched its annual Dutch elm disease spraying program. The spraying, which will last until late September or early October, will see city crews spray the chemical on stumps and other known areas of Dutch elm disease (DED) before moving on to spray trees in several neighbourhoods in the city including North River Heights, Riverview, Wolseley, and Seven Oaks. All spraying is done during the day to make it easier to identify elms.

The treatment on the bark lasts for two years and the spray is applied around the trunk starting at the ground up to about 50 centimeters, or as city entomologist Tax Stuart said, "about the height of a person's knee."

"They'll stay on the tree in winter -- that's a sign," he said, adding if people call 311 someone from the city will come down to make a diagnosis.