Euphorbia milii White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Powdery Mildew Cottony Blotch (Fungal/Bacterial)

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Mealybugs

These small insects secrete a white, waxy, cotton-like substance to protect themselves as they feed on the sap of the Euphorbia milii. They typically cluster in the crevices between the stems and near the leaf axils.

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 Treat the infestation by spraying the plant with an organic insecticide or neem oil to kill the insects and remove the waxy coating.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

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3 Use a cotton swab dipped in isopropyl alcohol to manually remove visible white clusters from the crevices of the stems.

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Powdery Mildew

This fungal pathogen manifests as a white, dusty coating on the leaves of the Crown of Thorns, often appearing when humidity is high and airflow is poor. It can eventually cause the foliage to yellow and drop.

Common

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How to confirm: Check if the white substance can be easily wiped off with your finger like flour or dust.

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1 Apply an organic fungicide to the affected leaves to eliminate the powdery mildew spores and prevent further spread.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

2 Improve air circulation around the plant and reduce humidity by avoiding overhead watering and ensuring the plant is not in a stagnant area.

3 Prune and dispose of any heavily infected leaves to prevent the fungus from spreading to healthy foliage.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

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Cottony Blotch (Fungal/Bacterial)

Certain opportunistic fungi can cause localized necrotic spots that appear fuzzy or raised as the plant tissue breaks down. This is often exacerbated by moisture sitting on the succulent stems of the Euphorbia.

Common

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How to confirm: Inspect the area under the white spot to see if the stem or leaf tissue has turned soft, dark, or mushy.

build How to fix it

shopping_cart Recommended Products

1 Apply an organic fungicide to the affected areas to stop the spread of the fungal blotch and protect healthy tissue.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

2 Prune away any heavily infected stems using sterilized shears to prevent the pathogen from spreading to the rest of the plant.

Fiskars 5/8" Bypass Pruning Shears