Should I use a fungicide?

Usually, it is not necessary for American senna. Simply removing the infected leaves and improving airflow is almost always enough.

Will the spots go away?

No, the damaged tissue will not heal. You should remove the spotted leaves so the plant can focus energy on new, healthy growth.

American senna: spots, causes and fixes

Check these first

Inspect the undersides of leaves for signs of fungal growth.
Check if the plant is crowded by other vegetation.
Observe if the spots are spreading after rain.

Likely causes

Fungal leaf spot
Most likely
How to tell: You will see dark or discolored circular spots appearing on the foliage, often with a yellow halo. These spots tend to spread during humid, rainy weather.
What to do: Remove and destroy all infected leaves immediately to stop the spread. Improve air circulation by thinning out nearby plants or pruning crowded branches. Avoid overhead watering to keep the foliage dry.
Bacterial blight
Possible
How to tell: This causes irregular, water soaked spots that may turn brown or black. It often happens after periods of heavy, persistent rainfall.
What to do: Prune away affected stems using sterilized shears. Ensure the plant is in a spot with good drainage to prevent water from pooling around the roots.

Leaf spots on other plants

Find out what's wrong with your american senna

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.

When to worry

Worry if the spots cover more than half the leaf surface or if the entire plant begins to wilt. A few small spots are common in late summer and are usually not fatal.

Stopping it coming back

Space your plants out to ensure good airflow and always water at the base of the plant rather than wetting the leaves.

American senna: spots? Check yours with a photo

Every plant is a little different. Take a photo of your american senna 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.

Get the app · Or check it from a photo now, free

Questions people ask

Should I use a fungicide?: Usually, it is not necessary for American senna. Simply removing the infected leaves and improving airflow is almost always enough.
Will the spots go away?: No, the damaged tissue will not heal. You should remove the spotted leaves so the plant can focus energy on new, healthy growth.

Guides to these causes

Leaf Spot

Why are there spots on my American senna leaves?

Check these first

Not sure what's wrong with your american senna?