Can I spray the tree with fungicide?

Fungicides are rarely practical for large, mature trees. Focus on sanitation and keeping the tree healthy instead.

Are these spots harmful to the nuts?

Some infections can affect the quality of the nut meat, but many minor leaf spots do not impact the harvest.

Black Walnut: spots, causes and fixes

Check these first

Examine the spots for a yellow halo or fuzzy texture.
Check if the spots are appearing on the nuts as well as the leaves.
Look for fallen leaves beneath the tree.

Likely causes

Anthracnose
Most likely
How to tell: Small, irregular brown or black spots appear on the leaves, often surrounded by a yellow halo. These spots may merge and cause the leaf to wither.
What to do: Rake up and destroy all fallen leaves to prevent spores from spreading. Prune out any dead or infected twigs to improve air circulation.
Bacterial Blight
Possible
How to tell: Dark, water soaked spots appear on leaves, stems, and nuts. These spots often turn black and can cause fruit to drop prematurely.
What to do: Avoid overhead watering to keep foliage dry. Remove and destroy infected plant parts immediately to stop the spread.

Leaf spots on other plants

Find out what's wrong with your black 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 the spotting leads to widespread premature leaf drop, it is a problem. Isolated spots are usually cosmetic and not a threat to the tree.

Stopping it coming back

Improve air circulation through proper pruning and keep the area under the tree clean of debris.

Black Walnut: spots? Check yours with a photo

Every plant is a little different. Take a photo of your black 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

Can I spray the tree with fungicide?: Fungicides are rarely practical for large, mature trees. Focus on sanitation and keeping the tree healthy instead.
Are these spots harmful to the nuts?: Some infections can affect the quality of the nut meat, but many minor leaf spots do not impact the harvest.

Guides to these causes

Anthracnose

What are these spots on my Black Walnut leaves?

Check these first

Not sure what's wrong with your black walnut?