Dutch elm disease (DED) is caused by a fungus spread by tiny elm bark beetles that breed under the bark of dead or dying elm wood. If that wood contains the DED fungus, each new generation of beetles can infect healthy elms.
Signs of Dutch Elm Disease
Beginning in late June to mid-July, look for:
- Flagging - when the leaves of one or more branches near the top of the tree may wilt, curl, turn yellow and then brown, remaining on the tree (pictured below).
- Staining - an infected twig sample will have red streaks through the sapwood.
Several other diseases have similar symptoms so the only way to confirm DED is in the lab. The Ministry of Agriculture's Crop Protection Laboratory offers free DED testing to Saskatchewan residents.
Don't Prune Elms from April 1 to August 31
Provincial regulations prohibit pruning of elm trees from April 1 to August 31 each year. The beetles are most active then, and fresh cuts attract them, increasing the chance of infection.
If your elm needs attention during the pruning ban, because of a lightning strike or wind damage, you can remove broken or hazardous branches, or the entire tree, but you must dispose of the wood right away in the designated location for your area. This is often the local landfill but contact your municipal authority to find out about proper elm wood disposal where you live. If you must take out the entire tree, remove the stump below ground level or treat it so that it doesn't attract beetles.
Regular pruning outside the ban period helps keep trees healthy. If you decide to hire someone to prune your elms, check their qualifications. Under provincial regulations, all commercial pruners of elm trees must complete a recognized training program or be supervised by someone who has. Improper pruning can spread diseases or damage your trees.
Preventing Dutch Elm Disease
- Keep your elm trees healthy;
- Abide by the provincial ban on pruning elm trees from April 1 to August 31;
- If you see signs of DED, report them to your municipal authority;
- Don't buy, sell, store, transport or use elm firewood;
- Remove and dispose of DED-infected trees promptly and properly; and
- Support DED management in your community.
No Elm Firewood in Saskatchewan
It's illegal to transport, store or buy elm firewood. Firewood is one of the largest spreaders of DED; elm bark beetles on infected firewood hitch a free ride with unsuspecting campers and homeowners, spreading the disease.
- Don't transport firewood when camping;
- Avoid elm when cutting or buying firewood;
- Don't store pruned elmwood to burn in a fireplace later.
Permit to Prune, Store, Use, Market or Transport Elm Trees
There may be exceptional circumstances that make it necessary to prune, store, use, sell or transport elm trees, including seedlings, but you MUST apply for authorization first. For more information, call the ministry's Inquiry Centre at 1-800-567-4224 or contact your local municipality's designated inspecting officer.