Calathea stromata White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Cottony Blight (Fungal Pathogen) Powdery Mildew

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Mealybugs

These small, soft-bodied insects secrete a white, waxy, cotton-like substance to protect themselves. They feed on the sap of Calathea stromata, often clustering in the crevices between leaves or near the stem base.

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 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 white cottony clusters from the leaves and stem crevices.

3 Apply an organic insecticide spray to the entire plant, ensuring you coat the undersides of leaves and the base of the stems to kill any remaining insects and larvae.

Bonide Captain Jack's Neem Oil 32 oz

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Cottony Blight (Fungal Pathogen)

Certain fungal species can manifest as white, fuzzy mycelium on leaf surfaces, especially in high-humidity environments like those preferred by Calatheas. This often occurs if air circulation is poor around the dense foliage.

Common

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How to confirm: Check if the white spots are accompanied by dark, necrotic lesions or spreading rot on the leaf tissue.

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1 Apply an organic fungicide to the affected leaves to eliminate the fungal mycelium and prevent the spread of the blight.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

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2 Improve air circulation around the dense foliage by using a small fan or spacing plants further apart to reduce humidity stagnation.

3 Prune and discard any heavily infected leaves to prevent the pathogen from spreading to healthy parts of the plant.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

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Powdery Mildew

This fungal disease appears as a fine white powder on the surface of the leaves. While more common in outdoor plants, it can affect Calathea stromata if there is high humidity combined with stagnant air.

Common

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How to confirm: Observe if the white coating can be wiped off easily like dust or if it seems embedded in the leaf structure.

build How to fix it

shopping_cart Recommended Products

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

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 avoid overhead watering to keep foliage dry.

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