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Garden asparagus · Asparagus officinalis

What are these reddish spots on my asparagus?

Reddish or brown spots on your asparagus stems are a classic sign of asparagus rust. This fungal disease thrives in humid conditions and can weaken your plants if left untreated. First, check if your plants have enough airflow to dry out after rain.

spots on a plant
Photo: Scot Nelson, CC0

Check these first

  1. Examine the stems for raised, rusty colored bumps.
  2. Check if the foliage stays wet for hours after watering.
  3. Ensure there is enough space between plants for air to move.

Likely causes

  1. Asparagus rust

    Most likely

    How to tell: You will see small, reddish brown pustules on the stems and leaves. These spots eventually turn black as the season progresses.

    What to do: Remove and destroy all infected plant parts immediately to stop the spread. Improve air circulation by spacing your plants further apart next season.

  2. Overhead watering

    Possible

    How to tell: Water sitting on the foliage for long periods creates the perfect environment for fungal spores to grow. You might see irregular brown spots appearing after wet weather.

    What to do: Switch to drip irrigation or water at the base of the plant only. Avoid getting the foliage wet when you water.

When to worry

Rust is serious because it reduces the plant's ability to photosynthesize and store energy for next year. If the entire patch is covered in spots, the plant may not survive the winter.

Stopping it coming back

Choose rust resistant varieties when planting your asparagus bed. Always clean up and remove all dead foliage at the end of the season to prevent spores from overwintering.

Not sure which one it is? Photograph your garden asparagus.

This page lists the usual causes. Pocket Botanist looks at your actual leaf 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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Questions people ask

Will my asparagus die from rust?
It can weaken the plant significantly, but it rarely kills it in one season. Consistent removal of infected parts is key to recovery.
Should I use a fungicide?
Fungicides are usually not necessary for home gardens. Good sanitation and proper spacing are much more effective.

More problems with Garden asparagus

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This article was generated with AI from the plant’s care profile and is general information, not horticultural advice. Read about how we build these guides.