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Check these first
- Inspect the undersides of the leaves for orange or brown dust.
- Check if the plant is crowded by other vegetation.
- Look for signs of moisture sitting on the leaves.
Likely causes
Rust fungus
Most likelyHow to tell: You will see small, raised orange or brown pustules on the undersides of the leaves. The top of the leaf may show yellow or pale patches.
What to do: Remove and destroy all infected leaves immediately to stop the spread. Avoid overhead watering to keep the foliage dry, and ensure there is plenty of airflow around the plant.
Leaf spot disease
PossibleHow to tell: These spots are usually darker, often with a yellow halo, and appear randomly across the leaf surface. They do not have the powdery texture of rust.
What to do: Prune away the affected foliage and dispose of it in the trash, not the compost. Apply a copper based fungicide if the infection continues to spread to healthy leaves.
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
If the spots cover more than half the leaf surface or start spreading to the stems, the plant is struggling to photosynthesize. Small, isolated spots are manageable with quick pruning.
Stopping it coming back
Space your plants out to encourage good air circulation and always water at the base of the plant rather than over the leaves.
Broad-leaved willowherb: spots? 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
- Can I save a leaf with rust?
- It is best to remove it entirely. Once the fungus has established, it is very difficult to clear from that specific leaf.
- Will these spots kill my plant?
- Usually no, but it will weaken the plant significantly. If left untreated, the plant may lose its vigor and stop blooming.
Guides to these causes
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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.