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Alder buckthorn · Frangula alnus

Why are there orange spots on my Alder buckthorn leaves?

Seeing orange spots on your Alder buckthorn often points to a fungal rust infection. Check the undersides of the leaves first to confirm if you see powdery orange or brown pustules.

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spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Inspect the underside of the leaves for orange spores.
  2. Check if the plant is crowded by other shrubs.
  3. Look for fallen leaves around the base.

Likely causes

  1. Rust fungus

    Most likely

    How to tell: Small orange or reddish spots appear on the leaf surface, often with matching dusty spores underneath. The leaves may eventually yellow and drop prematurely.

    What to do: Prune away and destroy all infected foliage immediately to stop the spread. Improve air circulation around the plant by thinning out crowded branches. Avoid overhead watering to keep the leaves dry.

  2. Leaf spot disease

    Possible

    How to tell: Dark brown or black spots with yellow halos develop on the foliage. This usually happens during periods of high humidity or prolonged rain.

    What to do: Remove affected leaves as soon as you spot them. Clean up any fallen debris around the base of the plant. Apply a copper based fungicide if the infection persists.

Leaf spots on other plants

Find out what's wrong with your alder buckthorn

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 spots cover more than half of the foliage or if the plant begins to lose leaves rapidly. A few spots are manageable, but widespread rust can weaken the shrub over time.

Stopping it coming back

Keep the area around your shrub clear of leaf litter and ensure it has plenty of space for airflow. Water at the base of the plant instead of wetting the leaves.

Alder buckthorn: spots? Check yours with a photo

Every plant is a little different. Take a photo of your alder buckthorn 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

Will these spots kill my plant?
Usually no, but it can stress the plant and make it look unsightly. Consistent care and removal of infected parts will help it recover.
Can I compost the infected leaves?
Do not compost them. The fungal spores can survive and spread back to your garden, so throw them in the trash instead.

Guides to these causes

More problems with Alder buckthorn

Back to the Alder buckthorn 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.