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Check these first
- Look for a white, powdery substance on the leaves.
- Check if the plant is crowded by other plants.
- Inspect the leaves for small brown or black lesions.
Likely causes
Powdery mildew
Most likelyHow to tell: White, flour like spots appear on the leaves and stems during dry spells.
What to do: Increase humidity around the plant and ensure good airflow. You can wipe the leaves with a damp cloth or use a mild fungicide if the infection is heavy.
Fungal leaf spot
PossibleHow to tell: Small brown or black spots with yellow halos appear on the foliage.
What to do: Remove the affected leaves immediately to stop the spread. Avoid overhead watering to keep the foliage dry.
Find out what's wrong with your lesser spearwort
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 of the leaf surface, the plant will struggle to photosynthesize. Treat it immediately to prevent the plant from declining.
Stopping it coming back
Keep the plant in a well ventilated area and avoid getting water on the leaves when you refill the tray.
Lesser spearwort: spots? Check yours with a photo
Every plant is a little different. Take a photo of your lesser spearwort 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
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Questions people ask
- Can I use neem oil for the spots?
- Yes, neem oil is effective against both powdery mildew and fungal leaf spots. Apply it in the evening to avoid leaf burn from the sun.
- Is this contagious to my other plants?
- Yes, fungal spores can travel through the air. Keep the infected plant away from your other plants until it is healthy again.
Guides to these causes
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Back to the Lesser spearwort 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.