To help prevent DED, the only time of the year to prune elms in Alberta is between October 1 and March 31. This is when the three vectors - the banded, native and smaller European elm bark beetles - that are responsible for spreading the deadly DED fungus are not active.
Elm bark beetles feed on healthy elms during the summer and breed and overwinter in dead and dying elm trees. If elm trees are pruned between April 1 and September 30, these vectors of the disease will be drawn to the scent of the fresh pruning cuts, potentially attracting infested beetles and infecting an otherwise healthy elm.
“Having your tree pruned properly is important,” says Janet Feddes-Calpas, executive director, Society to Prevent Dutch Elm Disease (STOPDED). “We recommend that all trees are pruned by a professional arborist such as an ISA Certified Arborist. They will determine what type of pruning is necessary to maintain or improve the health, appearance and safety of your trees. Improper pruning, topping or removing an excessive amount of live wood is not recommended, will weaken the tree’s structure and shorten its lifespan. It is essential that all elm dead wood be removed and properly disposed of by burning, burying or chipping by March 31. To prevent the spread of DED, do not store elm firewood."
“Alberta is still free of DED, although its borders are being pressed from two sides, Saskatchewan and Montana, both battling the disease. There is no cure once an elm is infected but DED can be prevented. We must stay vigilant to keep our elms healthy.”
More information on DED can be found at the STOPDED webpage or by calling 1-877-837-ELMS.
To connect with STOPDED: