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Southern Magnolia · Magnolia grandiflora

Why are there dark spots on my Southern Magnolia leaves?

Leaf spots are usually caused by fungal infections that thrive in humid or wet conditions. Check if the spots have a yellow halo or if they are accompanied by a black, powdery substance.

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spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Look for tiny bumps on the stems that indicate scale.
  2. Check if the spots are spreading rapidly.
  3. Clear away debris from under the tree canopy.

Likely causes

  1. Fungal Leaf Spot

    Most likely

    How to tell: Small brown or black spots appear on the leaves, sometimes with a yellow border. These spots often grow larger during rainy seasons.

    What to do: Remove and destroy any fallen leaves to prevent spores from spreading. Apply a copper based fungicide during early spring to protect new growth.

  2. Sooty Mold

    Possible

    How to tell: A black, powdery coating covers the leaves, which can be wiped off with your finger. This is caused by honeydew from scale insects.

    What to do: Identify and treat the scale insects on the branches. Once the insects are gone, the mold will eventually wash away with rain.

Leaf spots on other plants

Find out what's wrong with your southern magnolia

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

A few spots are common in humid climates and rarely kill the tree. Worry if more than half the leaves are covered or if the tree is losing significant foliage.

Stopping it coming back

Water at the base of the tree rather than overhead to keep the foliage dry. Provide enough space between plants for good air circulation.

Southern Magnolia: spots? Check yours with a photo

Every plant is a little different. Take a photo of your southern magnolia 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

Can I prune off the spotted leaves?
Yes, pruning infected leaves helps reduce the spread of fungal spores. Always sanitize your shears between cuts.
Is leaf spot contagious to other plants?
Most fungal leaf spots are host specific, but it is best to keep infected debris away from your other garden plants.

Guides to these causes

More problems with Southern Magnolia

Back to the Southern Magnolia 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.