It’s been more than three years since Campus Services & Business Operations (CSBO) Grounds staff identified and initiated a strategy for dealing with the emerald ash borer (EAB). Since then, as was predicted, the bug has proven to be as serious a threat to Ontario’s urban forests, including the green ash trees on York University’s campuses.
The key stages of the University’s EAB strategy are:
- assessment and monitoring;
- tree removal and replacement;
- restoration through homegrown nursery stock; and
- information and education.
For more information, visit York University’s EAB Information website.
A big part of the assessment and monitoring role has revolved around the University’s tree inventory system. As of September 2014, all the trees located on the Keele and Glendon campuses, with the exception of those in woodlot, now have a specific identity tag affixed to them. The tag helps Grounds staff to track each tree’s attributes, including size, health and exact location, using GPS coordinates, as well as all maintenance that has been performed on the tree. In total, 7,029 trees have been tagged at Keele campus and 849 trees have been tagged at Glendon campus. The complete inventory is available online.
A big part of the conservation efforts has been the continued use of Treeazin, a systemic bioinsecticide chemical recommended for use on infested trees with 30 per cent or less foliage loss. In 2012, when Grounds staff began injecting trees, it was believed that applications every other year would be adequate to ensure tree survival with minimal insect damage. Of the approximately 600 ash trees on the University’s campuses, the original goal was to preserve 90 healthy specimen trees. Unfortunately, as a result of significant damage that occurred during the ice storm that took place in December 2013, coupled with the ineffectiveness of the Treeazin in some trees that were already infested, the University’s inventory of green ash trees has been reduced to 43 healthy specimen trees. The plan now is to continue to inject these 43 trees on an annual basis, with the intention of sustaining these trees through the 12- to 15-year EAB infestation period predicted by urban forest experts.
In regard to the remaining 510 trees, Grounds staff have already removed approximately 250, including the stump and below-ground root system. They intend to remove the remaining non-injected trees over the next 12 months. The goal of this strategy is to replace every ash tree with a new tree in conjunction with the tree removal program. The replacement trees are all species that are native to Canada, including oak, tulip tree, cedar, maple, birch, ironwood, Amur cork tree and butternut, some of which are being provided through the University’s plant nursery.
Another element of conservation initiatives is using the wood from the trees that have been removed. Trunks from larger trees with appropriate form are being stockpiled with the intention of repurposing. Additionally, a number of trees have been given to the School of Arts, Media, Performance & Design for use by York University visual arts students who are studying sculpture. The remaining tree debris is being ground into wood chips that are being used as mulch and applied to shrub beds and existing treed areas on both the Keele and Glendon campuses.