Among the elm trees across Ontario, there are matriarchs, grand old trees that have withstood the terrible onslaught of Dutch elm disease, and Henry Kock wants to repopulate Ontario with their offspring.
We need elms, he says, because they’re so hardy they can thrive where other trees can’t. And because — and here he smiles, and turns to look at the photographs of matriarchs that he has pinned to his office wall, where most people would have pictures of loved ones — and because, he continues, elms, with their stately, arching crowns, are nature’s cathedrals, and we have been the poorer for their loss.
So Kock (pronounced Coke) is travelling the province, taking cuttings from the matriarchs, and bringing them back to graft to saplings at The Arboretum at Guelph University, where he is an interpretive horticulturalist.
Fifteen years after grafting, the trees will begin producing seeds, and Kock will test them for immunity. He’ll inject high doses of Dutch elm disease to see which can survive. He’ll also « measure their immune chemistry,’’ and do DNA finger printing « to see how broad is the gene pool.”
« With persistence, we’ll have an orchard of 50 or 60 trees from the best matriarchs.’’ And from their seeds Ontario will be able to replace its lost elms, he says.
In the year and a half since the Arboretum’s elm recovery program started, only about 150 matriarchs — elms with a trunk circumference of three metres or more — have been reported.
They’ve survived because their immune systems have walled off the disease. The death of elms is not caused by the beetles themselves, but by a fungus they carry. As the fungus spreads inside a tree, it blocks water-conducting vessels, and the tree literally dies of thirst.
Just as human immune systems can occasionally close off blood supplies to tumours, allowing people to survive cancer, the matriarchs have been able to trigger their immune systems to respond quickly and efficiently to wall off an invading fungus before it spreads to lethal levels.
It’s that genetic capability of immediate immune-system response that Kock wants to graft into his saplings.
`No one’s done this work before,’’ he says. « It’s completely new in the world of trees.’’
In the wild, elms play a important role as an early succession tree. Because they are so hardy, they immediately take root on soil that has been stripped of vegetation by a natural disaster, or by clearcutting. As they grow, they create the conditions for other trees to follow.
They can also thrive under the severe conditions that cities impose on trees. Kock was inspired to launch the program after he saw a matriarch on Dufferin St. in Toronto. « It was on the east side, where it got a majority of salt loading on windy days (because the wind in Toronto is usually from the west), and it was standing in a stretch of asphalt and concrete with only one square metre of grass around its base.
« We need large trees like it in our cities, instead of the little lollipop things that get planted,’’ he adds. They give grandeur to cities.
Elms are also extremely valuable for farmers. A line of elms facing the prevailing summer winds, will slow the winds as they filter through branches, thereby reducing their ability to dry out the land. In addition, the trees will add moisture to the winds as they pass through the leaves and that, too, will create better conditions for crops. The hardiness of elms will allow them to flourish, standing isolated in fields where there is no supporting vegetation.
The Arboretum program, however, requires funding. Kock has already raised $70,000 toward the cost of establishing the elm orchard, but the Arboretum needs at least double that. Kock also hopes to establish an endowment fund of $100,000 to finance continued testing and monitoring of the offspring.
Donations are tax deductible, and you can call Kock at (519) 824-4120, extension 2113 for details. Ask, and he may even send you one of his matriarch photos.