From April 1st to August 31st it will be illegal to prune elm trees in Saskatchewan.

The ban coincides with the time of year when the elm bark beetles that spread Dutch elm disease (DED) are most active. Fresh cuts from pruning can attract the tiny insects, increasing the chance of an infection.

The DED fungus becomes attached to the beetles during their breeding period and is then spread as the beetle moves to healthy elms to feed over the winter.

DED can affect any elm tree and once infected, the disease always kills over several seasons or sometimes in as little as three weeks.

"DED is a fungus that infects and kills an elm tree by clogging the water-conducting vessels and there is no cure for DED," stated Curtis Block, Parks Manager for the City of Weyburn. "An infected tree should be removed immediately and disposed of by either burning, burial, or taking it to the landfill for disposal."

Elm tree leaves are oval-shaped, with pointed tips, and serrated edges (photo courtesy of Curtis Block).

One of the most important ways that you can help prevent the spread of these invasive pests is to avoid the illegal practice of transporting firewood or wood products from an infested area into and around the province.

DED was first noticed in continental Europe in 1910 and then made its first appearance in Saskatchewan when one infected elm was discovered in Regina in 1981.

The disease has since become well established in the southeastern and northeastern areas of the province, having spread from Manitoba where it has been a problem since the 1970s.

The bark is usually light to dark grey with a grooved surface (photo courtesy of Curtis Block).

"So symptoms of elms that have been infected with the disease you will notice as early as June the leaves will wilt, turn yellow, then curl, and brown," Block explained. "Symptoms usually appear first in the tree crown and can be seen until the fall colors appear. However, the only real positive way to confirm that the disease is present is through laboratory analysis."

He added that the Parks Department will be surveying for Dutch elm disease throughout the city in June and July.

There are approximately 2,200 elms growing in Weyburn’s urban forest, roughly half of which are located on the City of Weyburn property. All of these trees continue to be at risk of contracting DED.

Siberian or Manchurian elms are also susceptible to DED. They can take the form of shrubby hedges or single trees. The leaves are smaller and more elongated than those of the American elm (photo courtesy of Curtis Block).

During regular surveillance in the summer of 2019, samples of suspected infected trees were sent off for laboratory analysis. Unfortunately, these trees have tested positive for DED.

The disease has also been identified in Estevan, Carlyle, Fillmore, Yellow Grass, and Trossachs areas.

Weyburn possesses a natural buffer zone. There are no native stands of elms lining rivers and waterways which can ease the progression of the disease.

The City employs a schedule where pruning occurs every fall and winter, resulting in each city-owned tree being pruned every five years. Basal spraying is also done to privately-owned elms following the receipt of written authorization from the property owner.

If you have any questions or concerns regarding Dutch Elm Disease, please do not hesitate to contact the City of Weyburn Parks Department at (306) 848-3290, email: ded@weyburn.ca, or contact the Government of Saskatchewan at 1-800-567-4224.

If you are unsure whether your property has an elm tree, or you suspect any elm of having DED, please apply for basal spraying online. The deadline to apply is Sept. 18 for the 2020 DED control program.