Do aphids kill American elms?

Aphids rarely kill a mature tree, but they can weaken it and cause leaf drop. Managing them early keeps the tree looking healthy.

Should I prune curled leaves?

You do not need to prune them unless they are completely dead. The tree will shed them naturally as it grows new foliage.

American elm: curling leaves, causes and fixes

Check these first

Examine the undersides of the leaves for tiny insects.
Check if the leaves look sticky or shiny.
Observe if the curling happens only during the hottest part of the day.

Likely causes

Aphid Infestation
Most likely
How to tell: You see tiny 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, use an insecticidal soap once a week for 2 weeks.
Heat Stress
Possible
How to tell: The leaves curl inward during the hottest part of the day and look dry or brittle.
What to do: Provide deep watering during dry spells to help the tree manage heat. Ensure the tree has adequate mulch to keep the root zone cool.

Curling leaves on other plants

Find out what's wrong with your american elm

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

It is serious if the entire canopy is curling and the leaves are turning brown or dropping. Minor curling during a heat wave is a normal protective response.

Stopping it coming back

Keep the tree healthy with proper watering and monitor for early signs of pests during the spring.

American elm: curling leaves? Check yours with a photo

Every plant is a little different. Take a photo of your american elm 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

Do aphids kill American elms?: Aphids rarely kill a mature tree, but they can weaken it and cause leaf drop. Managing them early keeps the tree looking healthy.
Should I prune curled leaves?: You do not need to prune them unless they are completely dead. The tree will shed them naturally as it grows new foliage.

Guides to these causes

Aphids

Why are the leaves on my American elm curling?

Check these first

Not sure what's wrong with your american elm?