Calathea sanderiana White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Cottony Scale Powdery Mildew

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Mealybugs

Mealybugs are small, soft-bodied insects that secrete a white, waxy, cottony substance to protect themselves. They feed on the sap of Calathea sanderiana, often clustering in the leaf axils or under the foliage.

Very Common

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How to confirm: Use a cotton swab dipped in rubbing alcohol to dab the white spots; if they dissolve and turn brown, it is likely mealybugs.

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1 Isolate the plant immediately to prevent the mealybugs from spreading to your other houseplants.

2 Use a cotton swab dipped in isopropyl alcohol to manually remove the visible white cottony clusters from the leaf axils and stems.

3 Apply an organic insecticide spray to the entire plant, ensuring you coat the undersides of leaves and crevices, to eliminate remaining insects and larvae.

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Cottony Scale

Scale insects can produce a white, fluffy appearance that mimics cotton. These pests attach themselves to the stems or undersides of the leaves, sucking nutrients and causing the plant to weaken.

Common

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How to confirm: Check for small, immobile bumps underneath the leaves or along the stems that feel slightly raised.

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1 Treat the affected areas with an organic insecticide to eliminate the scale insects and their eggs.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Carefully wipe the stems and undersides of leaves with a cotton swab dipped in isopropyl alcohol to remove visible scale pests.

3 Isolate the plant from other greenery to prevent the spread of the infestation to healthy plants.

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Powdery Mildew

This fungal pathogen manifests as white, flour-like patches on the leaf surface. It thrives in the high humidity environments Calatheas prefer if there is also poor air circulation.

Common

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How to confirm: Observe if the white spots look like a fine dust that can be partially wiped off with your finger.

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1 Treat the affected leaves immediately with an organic fungicide to stop the spread of the fungal pathogen.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Improve air circulation around the plant by using a small fan and ensure the plant is not crowded by other greenery.

3 Prune and discard any heavily infected leaves to prevent the mildew from spreading to healthy foliage.