Calathea setosa White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Cottony Scale Sclerotinia (Fungal Infection)

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Mealybugs

Mealybugs are small, soft-bodied insects that secrete a white, waxy, cotton-like substance to protect themselves. In Calathea setosa, they often cluster in the crevices between leaf stalks and the rhizome, sucking sap and weakening the plant.

Very Common

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How to confirm: Use a cotton swab dipped in rubbing alcohol to dab the 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 Treat the infestation by spraying the plant with an organic insecticide or neem oil to kill the insects and remove the waxy coating.

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3 Use a cotton swab dipped in rubbing alcohol to manually remove any visible white cottony clusters from the leaf crevices and rhizome.

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Cottony Scale

Certain types of scale insects produce a white, filamentous coating that can resemble cotton. These pests feed on the nutrient-rich sap of the Velvet Calathea, often causing the leaves to lose their characteristic deep purple sheen.

Common

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How to confirm: Check underneath the leaves for small, hard bumps or shells beneath the white fuzz.

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1 Isolate the plant immediately to prevent the scale insects from spreading to other houseplants.

2 Treat the affected leaves and stems with an organic insecticide spray to eliminate the scale insects and their white coating.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

3 Gently wipe away any visible cottony residue from the leaves using a cotton swab dipped in isopropyl alcohol.

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Sclerotinia (Fungal Infection)

While less common as surface 'cotton,' certain fungal pathogens can manifest as white, fuzzy mycelium on decaying organic matter or leaf bases. High humidity in Calathea environments can sometimes facilitate these fungal growths if air circulation is poor.

Common

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How to confirm: Inspect the base of the plant for any signs of mushy, dark brown stem decay accompanying the white fuzz.

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1 Remove and discard all heavily infected leaves to prevent the fungal mycelium from spreading to healthy tissue.

2 Apply an organic fungicide to the affected areas and surrounding leaves to control the spread of the pathogen.