Saskatoon has its first case of Dutch elm disease.

"It's very important we take control immediately very seriously and we are reacting immediately to this," said Darren Crilly, director of parks.

The disease has decimated American elm trees in other parts of Saskatchewan since it arrived in the 1980s. Saskatoon was free of it until this point.

It's caused by a fungus that clogs the water conduction system of the tree, causing it to wilt and die in one or two seasons. It's carried by the elm bark beetle.

Crilly said the disease is transported primarily through firewood, and that is the most likely way it came to Saskatoon.

The infected tree is in the Queen Elizabeth neighbourhood, but the city won't reveal the exact location. Crews started removing it on Tuesday.

The city's response plan includes the following:

immediate removal of all positive trees

disposal of infected trees at the city landfill

sampling of nearby trees

surveillance and testing of private and public trees in the surrounding area with an intensive search for elm material and other sources of infection

placing five additional elm bark beetle adult pheromone traps in the area to monitor bark beetle populations

Millions of elms across North America have been lost since Dutch elm disease was introduced in the 1930s.