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Oregon Grape · Mahonia aquifolium

What are these spots on my Oregon grape leaves?

Spots on Oregon grape foliage are typically caused by fungal infections that thrive in damp conditions. Look closely at the spots to see if they have a yellow halo or a powdery texture.

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spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Examine the underside of the leaves for pests.
  2. Look for a white powdery coating on the foliage.
  3. Check if the spots have yellow halos.

Likely causes

  1. Leaf spot fungus

    Most likely

    How to tell: You will see distinct brown or black spots on the leaves, often surrounded by a yellowish ring. These spots can grow and cause the leaf to drop early.

    What to do: Prune away the infected leaves to stop the spread. Clean up all fallen debris from around the base of the plant and dispose of it in the trash.

  2. Powdery mildew

    Possible

    How to tell: A white, dusty coating appears on the surface of the leaves. It usually happens when the plant is crowded or air circulation is poor.

    What to do: Thin out nearby plants to improve airflow. You can spray the leaves with a mixture of one tablespoon of baking soda in a gallon of water to help clear it up.

Leaf spots on other plants

Find out what's wrong with your oregon grape

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

Small, isolated spots are usually just a cosmetic nuisance. If the spots cover most of the foliage and cause significant leaf drop, you should treat the plant.

Stopping it coming back

Water at the base of the plant rather than overhead to keep the leaves dry. Space your shrubs out to ensure good air movement.

Oregon Grape: spots? Check yours with a photo

Every plant is a little different. Take a photo of your oregon grape 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 cut off all the spotted leaves?
Remove the worst leaves to keep the plant looking tidy and reduce fungal spores. Do not remove more than one third of the plant at once.
Will leaf spot kill my plant?
It rarely kills an established plant, but it can weaken it over time. Keeping the area clean and dry is the best defense.

Guides to these causes

More problems with Oregon Grape

Back to the Oregon Grape 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.