Do I need to spray the whole tree?

Focus your treatment on the areas where you see the most damage. For husk flies, timing the spray to when adults emerge is key.

Will these pests return every year?

Yes, they often overwinter in the soil beneath the tree. Consistent monitoring each summer is your best defense.

What is attacking my English walnut tree? Causes and fixes

Check these first

Squeeze the outer husks to see if they feel soft or mushy.
Look for sticky residue on the leaves.
Check the ground for prematurely fallen nuts.

Likely causes

Walnut Husk Fly
Most likely
How to tell: The husks turn soft and mushy, and you may see small white maggots inside. The shell of the nut will often be stained black.
What to do: Hang yellow sticky traps in the tree canopy in early July to monitor and catch adults. Use an organic spinosad spray if the infestation is heavy.
Aphids
Possible
How to tell: Leaves look sticky from honeydew and may curl or yellow. You will see tiny green or black insects on the undersides of leaves.
What to do: Spray the leaves with a strong stream of water to knock them off. If needed, apply insecticidal soap directly to the pests.

Pests on other plants

Find out what's wrong with your english walnut

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

If you lose a large portion of your crop to husk flies, it is time to intervene. Minor aphid presence is usually handled by beneficial insects.

Stopping it coming back

Keep the tree healthy with proper watering and prune to maintain good light penetration throughout the branches.

English walnut: pests? Check yours with a photo

Every plant is a little different. Take a photo of your english walnut 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

Do I need to spray the whole tree?: Focus your treatment on the areas where you see the most damage. For husk flies, timing the spray to when adults emerge is key.
Will these pests return every year?: Yes, they often overwinter in the soil beneath the tree. Consistent monitoring each summer is your best defense.

Guides to these causes

Aphids

What is attacking my English walnut tree?

Check these first

Not sure what's wrong with your english walnut?