Crassula arborescens White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Cottony Scale Powdery Mildew

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Mealybugs

These small, soft-bodied insects secrete a white, waxy substance to protect themselves, which appears as cottony tufts in the crevices of Crassula leaves and stems. They feed on plant sap, leading to yellowing and potential leaf drop.

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.

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

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Cottony Scale

Similar to mealybugs, scale insects produce a white, felt-like covering on the surface of the fleshy leaves. This can cause the Silver Dollar Plant's leaves to become stunted or discolored due to sap depletion.

Common

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How to confirm: Look for small, hard bumps underneath the white fuzz that do not move when prodded.

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1 Isolate the plant immediately to prevent the spread of scale insects to other houseplants.

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

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

3 Gently wipe away any visible white cottony spots using a cotton swab dipped in isopropyl alcohol to kill the insects on contact.

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Powdery Mildew

This fungal disease manifests as a white, powdery coating on leaf surfaces, often caused by high humidity or poor air circulation around the succulent leaves. While less common in succulents than in soft-leaved plants, it can occur if the Crassula is kept in damp environments.

Common

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How to confirm: Check if the white spots look more like a fine dust that can be wiped off easily compared to thick cottony clumps.

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

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Improve air circulation around the plant and reduce humidity by avoiding overhead watering, which keeps the foliage dry.

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