Branching Out in Tree Care: Beardsley Zoo’s First Tree Injections Target Beech Leaf Disease

Connecticut’s Beardsley Zoo is known for caring for hundreds of animals — but that care extends to another vital part of the ecosystem: its trees. This summer, the Zoo took an important step in protecting its living landscape by performing tree injections on two beech trees near the North American river otter habitat, marking the first time this treatment has been done on Zoo grounds.

The procedure, performed in partnership with the tree experts at Bartlett Tree Experts, targets Beech Leaf Disease (BLD) — a serious and growing threat to beech trees across the region. BLD is caused by microscopic worms (nematodes) that infiltrate the leaves, creating distinctive dark striping. This damage reduces the tree’s ability to photosynthesize by up to one-third, weakening it over time.
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“These trees provide critical shade and habitat value on Zoo grounds,” explained Jonathan Dancho, the Zoo’s Horticulturist. “If left untreated, we’d see more striping, leaf deterioration, and eventually the tree would take on a dry, ‘crispy’ appearance.”

After assessment by Bartlett’s experts, two trees were deemed in need of immediate treatment. The injections, which must be done early in the day when the trees are actively moving water and nutrients, took about five hours to complete. While not a cure, the treatment can reduce symptoms and stress, giving the trees a better chance at recovery. Results could be visible as soon as next year, and the Zoo will reassess the trees in two years to determine next steps.

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“This is about symptom and stress reduction,” Dancho said. “We can’t eliminate the disease, but we can give the tree more tools to fight back.”

The tree injections are just one example of the Zoo’s broader commitment to its plant collections. Connecticut’s Beardsley Zoo is a Level 1 Arboretum—a distinction awarded by ArbNet for collections that meet defined standards for tree diversity, documentation, and care. This year, the Zoo is working toward Level 2 Arboretum status, which requires an even greater diversity of species, formalized tree care policies, and educational outreach. “An arboretum isn’t just about planting trees,” Dancho emphasized. “It’s about protecting and maintaining them for generations to come.”

In addition to injections, Bartlett also provides other tree care for the Zoo, such as pruning trees and conducting regular inspections. As part of the zoo’s supported professional development Dancho plans  to continue his learnings by taking the Tree Risk Assessment course to further enhance the Zoo’s on-site expertise.
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By tackling threats like Beech Leaf Disease head-on and striving to reach Level 2 Arboretum accreditation, the Zoo ensures its grounds remain a thriving, shaded, and beautiful home — not just for its animals, but for the people who visit and the plants that complete the landscape.