Has your elm tree had its vaccine?

Winnipeg, the global leader in the fight against Dutch elm disease, is adding another weapon to its arsenal. Home to 165,000 elms, the continent’s largest intact elm population, the Peg boasts a vaunted forestry program, monitoring strategy, and even has a grassroots army of tree vigilantes. Since 1992, the not-for-profit Coalition to Save the Elms has been patrolling city streets, educating property owners and banding threatened elms with sticky pink belts filled with tanglewood glue. Like a spiderweb, the gooey mess entraps cankerworms and bark beetles, protecting the tree. But the battle to maintain the city’s stately canopy is far from won. In each of the past three years, Winnipeg has lost an annual 4,400 specimens, with the lush, green giants turning into gaunt, grey ghosts, says city forester Martha Barwinsky.

Starting next year, however, 200 city trees will get a shot in the trunk to prevent the disease, which has killed over 80 per cent of Toronto’s elm trees, and decimated elm populations in both Montreal and Ottawa (which recorded its first diseased tree in 1948, on Parliament Hill). But Dutch Trig, the biological vaccine developed at the University of Amsterdam, won’t help trees that are already infected. And the protection, which must be re-injected annually, won’t come cheap: roughly $60 to $120 per tree, say its Netherlands-based maker, BTL Bomendienst.

Further west, another tree is threatened: B.C.’s iconic arbutus. The root disease and cankerworms threatening that species is not proportional to what is facing Manitoba’s elms, says UBC forestry professor Robert Guy. Dutch elm disease “totally wipes out” populations, killing “every elm it comes across,” he says. The threats facing the arbutus are more manageable—“for now.” Climate change and new diseases, like “sudden oak death,” found in arbutus in California, could quickly change that, he warns, imperilling the magnificent, crooked trees that cling to B.C.’s rocky south coast.