Pocket Botanist
Check these first
- Inspect the underside of the leaves for spores.
- Check if the spots are spreading to new growth.
- Look for signs of high humidity or poor airflow.
Likely causes
Ascochyta Leaf Spot
Most likelyHow to tell: Small, circular spots with light centers and dark borders appear on the leaves.
What to do: Remove and destroy all affected leaves immediately to stop the spread. Do not compost these leaves as the fungus can survive.
Ramularia Leaf Spot
PossibleHow to tell: Numerous small, irregular spots that may merge to cover large parts of the leaf.
What to do: Ensure good air circulation by spacing your plants at least 3 feet apart. Avoid overhead watering to keep the foliage dry.
Find out what's wrong with your rhubarb
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
A few small spots are common in late summer, but widespread spotting that causes leaves to wither is a concern. Remove heavily infected leaves to keep the plant healthy.
Stopping it coming back
Water at the base of the plant rather than over the leaves to keep them dry.
Rhubarb: spots? Check yours with a photo
Every plant is a little different. Take a photo of your rhubarb 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
- Are leaves with spots safe to eat?
- Rhubarb leaves are toxic and should never be eaten, spotted or not. The stalks are usually fine if they show no signs of infection.
- Should I use a fungicide?
- Fungicides are rarely necessary for home gardeners. Proper sanitation and spacing are much more effective.
More problems with Rhubarb
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.