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Blackhaw Viburnum · Viburnum prunifolium

What is the white dust on my Blackhaw Viburnum leaves?

That white, powdery coating is almost certainly powdery mildew. It thrives in humid, stagnant air and often appears during the warmer months. Check the leaves for a dusty appearance that wipes off easily.

Not sure it's this? Check a photo of your plant for free

spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Rub the white spots to see if they wipe off.
  2. Check if the plant is in a spot with poor airflow.
  3. Look for signs of moisture on the leaves.

Likely causes

  1. Powdery mildew

    Most likely

    How to tell: Leaves look like they have been dusted with flour or talcum powder. The spots may start small and eventually cover the entire leaf surface.

    What to do: Improve air circulation by thinning out crowded branches. Spray the foliage with a mixture of one tablespoon of baking soda and one teaspoon of liquid soap in a gallon of water.

  2. Fungal leaf spot

    Possible

    How to tell: Dark brown or black spots with yellow halos appear on the leaves. These spots are usually firm and do not wipe off.

    What to do: Remove and destroy all fallen leaves around the base of the plant to prevent spores from spreading. Avoid overhead watering to keep the foliage dry.

Leaf spots on other plants

Find out what's wrong with your blackhaw viburnum

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 mildew covers most of the leaves, as it prevents the plant from photosynthesizing properly. It is rarely fatal but looks unsightly.

Stopping it coming back

Plant your viburnum in a location with good sun and space it properly from other shrubs to ensure air moves freely.

Blackhaw Viburnum: spots? Check yours with a photo

Every plant is a little different. Take a photo of your blackhaw viburnum 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 the infected leaves?
Yes, removing heavily infected leaves can help slow the spread of the fungus. Just be sure to dispose of them in the trash rather than composting them.
Does this mean my plant is dying?
Not at all. Powdery mildew is a common cosmetic issue for viburnums and rarely kills the plant. It is mostly a sign that the environment is a bit too humid or crowded.

Guides to these causes

More problems with Blackhaw Viburnum

Back to the Blackhaw Viburnum 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.