Pocket Botanist
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Check these first
- Inspect the undersides of the leaves for clusters of small insects.
- Look for sticky honeydew or black sooty mold on the leaves.
- Check the stems for small, immobile bumps.
Likely causes
Filbert Aphids
Most likelyHow to tell: You will see clusters of tiny green or yellow insects on the leaf undersides and a sticky residue called honeydew on the foliage below.
What to do: Spray the leaves with a strong stream of water to knock them off. If the infestation is heavy, apply insecticidal soap or neem oil every 7 days until they are gone.
Scale Insects
PossibleHow to tell: These look like small, hard brown bumps attached to the stems or leaf veins that do not move.
What to do: Scrape them off gently with a soft brush or fingernail. For larger issues, apply horticultural oil during the dormant season to smother the eggs.
Find out what's wrong with your common hazel
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
A few aphids are normal, but if they cover the entire plant or cause the leaves to curl, you need to intervene. If you see sooty mold, treat the aphids immediately to stop the fungus.
Stopping it coming back
Encourage beneficial insects like ladybugs to visit your garden by planting diverse flowers nearby. Keep the tree healthy with proper watering to help it resist infestations.
Common Hazel: pests? Check yours with a photo
Every plant is a little different. Take a photo of your common hazel and Pocket Botanist tells you which cause is most likely, how serious it is, and what to try first. A few checks a day are free. Save the plant and you get care reminders timed for it.
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Or go to pocketbotanist.app/get on your phone
Get the app · Or check it from a photo now, free
Questions people ask
- Will aphids kill my hazel tree?
- Usually no, but they can stress the tree and cause cosmetic damage. Severe infestations over many years can weaken the plant.
- Is the sticky stuff on my leaves harmful?
- The honeydew itself is just sugar, but it attracts ants and encourages the growth of black sooty mold. Wash it off with water to prevent mold buildup.
Guides to these causes
More problems with Common Hazel
- Why are there spots on my Common Hazel leaves?
- Why are my Common Hazel leaves turning yellow?
- Why are my common hazel's leaf tips turning brown?
- Why is my common hazel drooping?
- Why is my common hazel dropping its leaves?
- Why is my common hazel not producing catkins?
- How do I fix root rot on my common hazel?
- Why are the leaves on my hazel tree curling?
Back to the Common Hazel guide
This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.