Pocket BotanistCheck these first
- Inspect the leaves for orange spots.
- Check the trunk for holes or sawdust.
- Verify the soil moisture levels.
Likely causes
Leaf rust
Most likelyHow to tell: You will see small orange or yellow spots on the leaves that eventually cause them to turn yellow and fall off. This fungal infection spreads quickly in humid conditions.
What to do: Remove and destroy all fallen leaves to stop the fungus from spreading. Apply a copper based fungicide to the foliage during the early stages of infection.
Poplar borer
Most likelyHow to tell: Look for small holes in the trunk or sawdust like frass at the base of the tree. These larvae tunnel into the wood and cut off the tree's water supply.
What to do: Consult a professional arborist to treat the tree with systemic insecticides. Keep the tree healthy with proper watering to help it resist further damage.
Find out what's wrong with your cottonwood
The list above covers the usual causes. Pocket Botanist looks at a photo of your actual plant and tells you the likely cause, how serious it is, and what to try first. Identification and a health check are free.
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When to worry
It is normal for poplars to drop leaves in late autumn as they prepare for winter. Worry if the tree loses leaves during the peak of summer.
Stopping it coming back
Keep the area around the base of the tree clear of debris and ensure it gets full sun to keep leaves dry.
Keep your cottonwood healthy from here
Save your plant in Pocket Botanist and you get care reminders timed for this plant, plus a care history that shows what worked. Identification and a health check are free.
Questions people ask
- Will my tree die from leaf rust?
- Usually not, but it weakens the tree over time. Consistent treatment helps it recover.
- Can I save a tree with borers?
- If caught early, yes. If the infestation is severe, the tree may become structurally unsafe.
More problems with Cottonwood
This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.