Can aphids kill my tree?

Aphids rarely kill a mature tree, but they can weaken it. It is best to treat them early to prevent the leaves from curling and dropping.

Should I prune the curled leaves?

No, leave the leaves on the tree. They can still photosynthesize even if they are curled.

Why are my Japanese zelkova leaves curling? Causes and fixes

Check these first

Inspect the undersides of the leaves for tiny insects.
Check the soil moisture to see if the tree is thirsty.
Look for sticky residue on the leaves.

Likely causes

Aphid infestation
Most likely
How to tell: You will see small green or black insects on the undersides of leaves and a sticky substance called honeydew on the foliage.
What to do: Spray the leaves with a strong stream of water to knock the aphids off. If the infestation is heavy, apply insecticidal soap every 5 to 7 days until they are gone.
Heat stress
Possible
How to tell: The leaves curl inward during the hottest part of the day but look better in the evening. This is less common for this tree unless it is newly planted.
What to do: Apply a 2 to 3 inch layer of mulch around the base to keep the roots cool. Ensure you are watering deeply every 7 to 14 days during the first few years.

Curling leaves on other plants

Find out what's wrong with your japanese zelkova

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.

When to worry

Worry if the curling is accompanied by yellowing or premature leaf drop. Minor curling during a heatwave is often just the tree protecting itself.

Stopping it coming back

Keep the tree healthy with consistent deep watering and monitor for pests early in the spring.

Japanese zelkova: curling leaves? Check yours with a photo

Every plant is a little different. Take a photo of your japanese zelkova 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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Questions people ask

Can aphids kill my tree?: Aphids rarely kill a mature tree, but they can weaken it. It is best to treat them early to prevent the leaves from curling and dropping.
Should I prune the curled leaves?: No, leave the leaves on the tree. They can still photosynthesize even if they are curled.

Guides to these causes

Aphids

Why are my Japanese zelkova leaves curling?