The only time it is legal to prune elms in Alberta is between October 1 and March 31.
‘With the annual ban lifted, it’s time to start taking the dead wood out of your elm trees,’ says Janet Feddes-Calpas, executive director of the Society to Prevent Dutch Elm Disease (STOPDED). ‘To help eliminate elm bark beetle habitat, elm sanitation is essential to an integrated Dutch elm disease (DED) prevention program to keep Alberta DED free.’
She explains that between October 1 and March 31, is the time when the elm bark beetles - responsible for spreading the deadly DED fungus - are not active. Elm bark beetles feed on healthy elms, breed and overwinter in dead and dying elm trees.
‘If elm trees are pruned between April 1 and September 30, beetles will be drawn to the scent of the fresh pruning cuts, potentially infecting an otherwise healthy elm.’
She adds that having elm trees pruned properly is important and that STOPDED recommends that all trees be 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, as this type of pruning will weaken the tree’s structure and shorten its lifespan. It is essential that all pruned elm wood be properly disposed of by burning, burying or chipping by March 31. And, it’s illegal to store elm firewood since it could be harbouring elm bark beetles.’
In August, 2020, DED was confirmed in 2 elm trees in Lethbridge. They were removed immediately from a public boulevard and disposed by the City of Lethbridge. With the removal of these infected trees, Alberta continues to have non-infested status.
Alberta continues to be pressed from its borders with Saskatchewan and Montana, both of which are battling the disease.
‘There is no cure once an elm is infected with DED, and it must be removed and destroyed immediately,’ she says. ‘We must stay vigilant to keep our elms healthy. DED can be prevented.’
Source : alberta.ca