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Broad-leaved willowherb · Epilobium montanum

What are these bugs on my Epilobium montanum?

It is less common for this plant to suffer from major pest infestations, but it can occasionally attract aphids or rust fungi. Check the undersides of the leaves first to see if you can spot any tiny insects or orange powdery patches.

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pests on a plant
Photo: Jules Verne Times Two, CC BY-SA 4.0

Check these first

  1. Inspect the undersides of the leaves for orange spots or tiny bugs.
  2. Look for sticky residue on the stems or foliage.
  3. Check if the plant is crowded by other plants, which limits airflow.

Likely causes

  1. Rust fungus

    Most likely

    How to tell: You will see small orange or brown powdery spots on the undersides of the leaves. In severe cases, the leaves may yellow and drop prematurely.

    What to do: Remove and destroy any heavily infected leaves immediately to stop the spread. Improve air circulation around the plant and avoid overhead watering to keep the foliage dry.

  2. Aphids

    Possible

    How to tell: Tiny green or black insects cluster on the new growth and flower buds. You might also see sticky residue on the leaves.

    What to do: Spray the plant with a strong stream of water to knock the aphids off. If they persist, apply insecticidal soap once a week until they are gone.

Pests on other plants

Find out what's wrong with your broad-leaved willowherb

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

Rust is serious if it covers most of the foliage, as it weakens the plant significantly. A few aphids are normal and usually manageable.

Stopping it coming back

Keep the plant well spaced for good airflow and water at the base rather than over the leaves.

Broad-leaved willowherb: pests? Check yours with a photo

Every plant is a little different. Take a photo of your broad-leaved willowherb 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

Is the rust fungus harmful to me?
It is a plant-specific fungus and does not affect humans. Just wash your hands after handling infected leaves.
Can I use neem oil for the pests?
Yes, neem oil is effective against both aphids and mild fungal issues. Apply it in the evening to avoid burning the leaves in the sun.

Guides to these causes

More problems with Broad-leaved willowherb

Back to the Broad-leaved willowherb 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.