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Western columbine · Aquilegia formosa

Why are there white lines on my Western columbine leaves?

Seeing winding white tunnels or a white powdery coating on your columbine is a common sign of pest or fungal activity. Check the undersides of the leaves and the overall leaf surface to identify the culprit.

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pests on a plant
Photo: Jules Verne Times Two, CC BY-SA 4.0

Check these first

  1. Inspect the leaves for winding white tunnels.
  2. Look for a white, dusty film on the leaf surfaces.
  3. Check the undersides of leaves for tiny insects.

Likely causes

  1. Columbine leaf miner

    Most likely

    How to tell: You will see distinct, winding white tunnels or squiggly lines inside the leaf tissue. These are caused by larvae feeding between the leaf layers.

    What to do: Prune off and destroy the infested leaves immediately to stop the cycle. Do not compost these leaves, as the larvae can survive. You can also apply neem oil to the foliage every 7 to 10 days if the infestation is widespread.

  2. Powdery mildew

    Most likely

    How to tell: A white, dusty fungal coating appears on the surface of the leaves during humid or stagnant weather. It often looks like someone sprinkled flour on your plant.

    What to do: Improve air circulation around the plant by thinning out nearby foliage. Spray the leaves with a mixture of one tablespoon of baking soda in a gallon of water. Apply this every 7 to 14 days until the white coating disappears.

Pests on other plants

Find out what's wrong with your western columbine

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

You should worry if the tunnels cover more than half of the leaf surface, as this prevents the plant from photosynthesizing. Minor cosmetic damage is usually not fatal.

Stopping it coming back

Keep the area around your columbine clear of debris and ensure good airflow to discourage both pests and fungi. Water at the base of the plant rather than overhead to keep leaves dry.

Western columbine: pests? Check yours with a photo

Every plant is a little different. Take a photo of your western columbine 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.

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Questions people ask

Will the leaf miner kill my plant?
Usually no, it is mostly a cosmetic issue. However, heavy infestations can weaken the plant over time.
Can I wash off the powdery mildew?
You can wipe it off, but it will return unless you treat the fungus and improve airflow. Focus on keeping the foliage dry.

Guides to these causes

More problems with Western columbine

Back to the Western columbine 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.