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.
Below is a list of the more common pests and diseases that can occur in Calgary's trees:
- Aphids - small pear shaped insects that feed on plant sap.
- Ash leaf cone roller - caterpillar/moth like insect that rolls tree leaves.
- Ash psyllid - small insects on tree leaves, resulting in curling leaves.
- Black knot fungus - large knots (abnormal growths) of bark that encircle the branch.
- Bronze leaf disease (BLD) - effects certain poplar and aspen trees.
- Elm scale - tiny crawling insects on leaves, twigs and branches.
- Fire blight - a bacterial disease that browns and kills leaves, flowers and branches.
- Oystershell Scale - small clusters of oyster-shaped “shells” that cover bark on shrubs and trees
- Satin moth - feeds on poplar tree leaves.
- Yellow-headed spruce sawfly - caterpillar like insect on spruce needles.
Invasive Threats to Calgary's urban forest
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.
Emerald Ash Borer is an invasive beetle found in Eastern Canada which poses an extreme threat to Calgary's ash trees. Currently there have been no detections in Alberta, but we continue to monitor for its presence.