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Honey locust · Gleditsia triacanthos

What are these spots on my Honey locust leaves?

Spots on Honey locust leaves are typically caused by fungal infections that thrive in wet or humid conditions. While they look unsightly, they rarely threaten the life of a mature tree. Check if the spots appear after a period of heavy rain.

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spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Look for fallen leaves under the tree.
  2. Check the bark for sunken, discolored patches.
  3. Observe if the spots are mostly on the lower, inner branches.

Likely causes

  1. Leaf spot fungus

    Most likely

    How to tell: Small, dark, or tan spots appear on the leaflets, sometimes with a yellow halo. The spots may merge as the season progresses.

    What to do: Rake up and dispose of all fallen leaves in the autumn to remove fungal spores. Avoid overhead watering that wets the leaves, as this encourages fungal growth.

  2. Canker infections

    Possible

    How to tell: While primarily a bark issue, early fungal activity can sometimes manifest as irregular spotting on foliage near the infection site. Look for sunken bark areas nearby.

    What to do: Prune out any branches showing signs of sunken, dead bark. Ensure the tree has good air circulation by thinning out crowded branches.

Leaf spots on other plants

Find out what's wrong with your honey locust

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.

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When to worry

Worry if the spotting leads to premature leaf drop or if you see large, sunken cankers on the main branches. Most leaf spots are just a seasonal nuisance.

Stopping it coming back

Keep the area under the tree clean of debris to reduce spore buildup. Water at the base of the tree rather than sprinkling the leaves.

Honey locust: spots? Check yours with a photo

Every plant is a little different. Take a photo of your honey locust 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

Should I spray my tree with fungicide?
Fungicides are rarely necessary for Honey locusts. Good sanitation and proper watering are usually enough to manage the problem.
Will the spots spread to my other plants?
Most leaf spot fungi are host specific, meaning they only affect certain types of trees. Your other garden plants are likely safe.

Guides to these causes

More problems with Honey locust

Back to the Honey locust guide

This article was generated with AI on from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.