Can I save stems with spots?

It is best to remove them. Once the fungus takes hold, it is hard to clear up, and removing the stems prevents it from moving to the rest of the plant.

Will the spots kill my plant?

If left untreated, a severe rust infection can weaken the plant significantly. Early intervention usually keeps the plant healthy.

Marsh horsetail: spots, causes and fixes

Check these first

Inspect the stems closely for powdery orange dust.
Check the airflow around the plant.
Look for signs of moisture trapped against the stems.

Likely causes

Fungal Rust
Most likely
How to tell: You will see small, powdery orange or reddish pustules on the stems. These spots often appear after periods of high humidity or poor airflow.
What to do: Prune away the heavily infected stems immediately to stop the spread. Improve air circulation around the plant by moving it to a spot with a light breeze or using a small fan.
Water Splashing
Possible
How to tell: Small brown or orange spots appear near the base of the plant where water frequently splashes onto the stems. This is often just surface staining rather than a disease.
What to do: Water the soil directly at the base rather than pouring water over the stems. Ensure the plant is not sitting in a location where it gets splashed by other nearby plants.

Leaf spots on other plants

Find out what's wrong with your marsh horsetail

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

If the spots are spreading rapidly to healthy stems, you need to act fast to save the plant. A few isolated spots are usually manageable with simple pruning.

Stopping it coming back

Keep the plant in a location with good natural airflow and avoid overhead watering.

Marsh horsetail: spots? Check yours with a photo

Every plant is a little different. Take a photo of your marsh horsetail 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

Can I save stems with spots?: It is best to remove them. Once the fungus takes hold, it is hard to clear up, and removing the stems prevents it from moving to the rest of the plant.
Will the spots kill my plant?: If left untreated, a severe rust infection can weaken the plant significantly. Early intervention usually keeps the plant healthy.

Guides to these causes

Rust

Why does my marsh horsetail have orange spots?