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San Pedro cactus · Echinopsis pachanoi

What are these white cottony spots on my San Pedro?

Mealybugs are the most common pest for San Pedro cacti, appearing as small, white, fuzzy patches. They hide in the ribs and crevices of the plant to suck its sap.

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

Check these first

  1. Look closely in the deep ribs of the cactus for white fuzz.
  2. Check the base where the cactus meets the soil.
  3. Wipe a spot with a damp cloth to see if it smears like cotton.

Likely causes

  1. Mealybug Infestation

    Most likely

    How to tell: You see white, cottony masses tucked into the ribs or near the base. The plant may look slightly dehydrated despite regular watering.

    What to do: Dab the bugs with a cotton swab dipped in 70 percent isopropyl alcohol to kill them on contact. For larger infestations, spray the entire plant with insecticidal soap or neem oil.

  2. Poor Air Circulation

    Possible

    How to tell: The plant is kept in a stagnant, humid area where pests thrive. You might notice the white fuzz spreading quickly.

    What to do: Move your cactus to a spot with better airflow. Ensure it gets plenty of direct sunlight to keep the surface dry and inhospitable to pests.

Pests on other plants

Find out what's wrong with your san pedro cactus

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

If the infestation covers the entire plant, it can weaken the cactus significantly. Treat it as soon as you see the first white spot.

Stopping it coming back

Inspect your cactus weekly and keep it in a well ventilated area with plenty of direct sun.

San Pedro cactus: pests? Check yours with a photo

Every plant is a little different. Take a photo of your san pedro cactus 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

Are mealybugs harmful to my cactus?
Yes, they suck the sap and can stunt growth. They also leave behind residue that can lead to fungal issues.
Do I need to isolate my plant?
Yes, move it away from other plants immediately to prevent the bugs from spreading.

Guides to these causes

More problems with San Pedro cactus

Back to the San Pedro cactus 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.