Pocket Botanist
Check these first
- Look for white dust on the leaf surfaces.
- Check if the plant is crowded by other foliage.
- Inspect the underside of the leaves for pests.
Likely causes
Powdery mildew
Most likelyHow to tell: You will see a white, dusty fungal growth covering the leaves.
What to do: Increase air circulation around the plant by spacing it further from others. You can also apply a neem oil spray or a mixture of water and baking soda to the affected leaves.
Fungal leaf spot
PossibleHow to tell: Small brown or black spots appear on the foliage, often with a yellow halo.
What to do: Remove the infected leaves to stop the spread. Avoid overhead watering to keep the foliage dry.
Find out what's wrong with your western mugwort
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.
Scan with your phone's camera to get the app
Or go to pocketbotanist.app/get on your phone
When to worry
If the spots cover most of the foliage and the plant starts dropping leaves, it needs immediate treatment.
Stopping it coming back
Provide full sun and ensure plenty of space between plants for good airflow.
Western mugwort: spots? Check yours with a photo
Every plant is a little different. Take a photo of your western mugwort 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.
Scan with your phone's camera to get the app
Or go to pocketbotanist.app/get on your phone
Get the app · Or check it from a photo now, free
Questions people ask
- Is powdery mildew harmful?
- It weakens the plant by blocking sunlight and can cause leaf drop if left untreated.
- Should I cut off spotted leaves?
- Yes, removing infected leaves helps prevent the fungus from spreading to healthy parts of the plant.
Guides to these causes
More problems with Western mugwort
- Why is my Western mugwort suffering from root rot?
- Why is my Western mugwort growing so leggy?
- Why are my Artemisia ludoviciana leaves turning yellow?
- Why are my Artemisia ludoviciana leaf tips turning brown?
- Why is my Artemisia ludoviciana drooping?
- Why is my Artemisia ludoviciana dropping its leaves?
- Are there bugs on my Western mugwort?
- Why are the leaves on my Artemisia curling?
Back to the Western mugwort 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.