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Sooty mold

November 28, 2014 by Jonas Dupuich

You’ve likely seen it – that dirty, cruddy stuff in your garden, on street trees, and on your bonsai. It has a name – sooty mold.

Sooty mold

Sooty mold on camellia

Although it can look creepy up close, it’s not among the more harmful garden pests. Sooty mold is fungus that grows on the honeydew secreted by aphids, scale or other insects that feed on sap.

Sooty mold

Sooty mold close-up

While the mold itself is rarely a threat to bonsai, the insects that generate the honeydew are. On the plus side, if you can control the pests, you can control the sooty mold.

Sooty mold

Sooty mold on the underside of a camellia leaf

What to do when you see sooty mold on bonsai?

  • Find out what’s creating the honeydew
    • If it’s coming from a garden tree overhead, consider moving the bonsai away from the infested tree
    • If it’s coming from scale, aphids or other insects on the bonsai itself, treat those insects with insecticidal soap, oils, contact pesticides and/or systemic pesticides
  • Make sure the bonsai is getting enough sunlight and is being watered properly

Aphids

Sooty mold on pine foliage

If the leaves are sturdy enough, sooty mold can be wiped away. If this isn’t a good option because of leaf size (chojubai), shape (pine needles) or fragility (azalea), overhead watering – as long as the foliage doesn’t stay wet for too long – can help rinse the mold away.

✕

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Filed Under: Bonsai Care Tagged With: Pests

Previous Post: « Pest of the week – aphid
Next Post: Powdery mildew »

Reader Interactions

Comments

  1. polianthus says

    November 28, 2014 at 12:48 pm

    my bonsais never live that long sadly..

  2. Mark @ BonsaiDojo says

    November 30, 2014 at 12:30 pm

    Looks like a case of treating the cause, not the symptom. If you notice the insects that secrete the honeydew, time to move your Bonsai away and treat it to make sure it doesn’t get any mould 🙂

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