Are the galls killing my tree?

No, the sumac gall aphid is a common visitor and the galls are purely cosmetic. Your tree will continue to grow just fine.

Should I spray the aphids with pesticide?

It is not recommended. Pesticides often kill beneficial insects and the galls do not harm the tree enough to justify the chemical use.

Why are my smooth sumac's leaves curling? Causes and fixes

Check these first

Inspect the undersides of the leaves for small insects or galls.
Check if the soil is dry more than 3 inches deep.
Observe if the leaves flatten out when the temperature drops in the evening.

Likely causes

Sumac gall aphid
Most likely
How to tell: You will see small, distinct, bumpy galls forming on the leaflets. These are harmless to the overall health of the tree.
What to do: You do not need to treat these as they cause no long term damage. If the appearance bothers you, simply prune off the affected branches with clean shears.
Heat stress
Most likely
How to tell: The leaves curl inward during the hottest part of the day to conserve moisture. They usually look normal again by the next morning.
What to do: Ensure the soil remains moist by watering deeply every 7 to 14 days. Apply a 2 to 3 inch layer of mulch around the base to keep the roots cool.

Curling leaves on other plants

Find out what's wrong with your smooth sumac

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

Do not worry if the tree looks healthy otherwise, as galls are normal for this species. Seek help if the entire canopy curls and stays that way even after watering.

Stopping it coming back

Keep the tree well watered during its first year to build a strong root system. Avoid over fertilizing which can create soft growth that attracts aphids.

Smooth sumac: curling leaves? Check yours with a photo

Every plant is a little different. Take a photo of your smooth sumac 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.

Get the app · Or check it from a photo now, free

Questions people ask

Are the galls killing my tree?: No, the sumac gall aphid is a common visitor and the galls are purely cosmetic. Your tree will continue to grow just fine.
Should I spray the aphids with pesticide?: It is not recommended. Pesticides often kill beneficial insects and the galls do not harm the tree enough to justify the chemical use.

Why are my smooth sumac's leaves curling?