Tree pests and diseases
There are many different pests or diseases that can infest Calgary's urban forest. Some are beneficial to the trees, but many are not.
Common pests and diseases in trees
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Small pear shaped insects that feed on plant sap.
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Caterpillar/moth like insect that rolls tree leaves.
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Large knots (abnormal growths) of bark that encircle the branch.
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Insects that feed on the leaves, flowers and seed pods of ash and maples .
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Effects certain poplar and aspen trees.
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An invasive pest which affects black and Manchurian ash trees.
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Tiny crawling insects on leaves, twigs and branches
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A bacterial disease that browns and kills leaves, flowers and branches.
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Small clusters of oyster-shaped “shells” that cover bark on shrubs and trees.
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Feeds on poplar tree leaves.
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Caterpillar like insect on spruce needles.
Invasive Threats to Calgary's urban forest
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Dutch elm disease is a fungus spread in elm trees by the elm bark beetle. Alberta is DED-free and works diligently to stay that way.
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Emerald ash borer is an invasive beetle that poses a threat to our ash trees if it arrives in Calgary. Currently there have been no detections in Alberta, but we continue to monitor for its presence.