Crassula fusca White Cottony Spots - Causes & Fixes

Jump to cause: Mealybug Infestation Powdery Mildew Cottony Blight (Sclerotinia)

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Mealybug Infestation

Mealybugs are common pests for Crassula species that secrete a white, waxy, cottony substance to protect themselves. They suck the sap from the fleshy leaves of the Dune Stonecrop, often causing leaves to shrivel or turn yellow.

Very Common

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How to confirm: Use a small paintbrush or cotton swab soaked in rubbing alcohol to see if the white spots dissolve upon contact.

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1 Isolate the plant immediately from other greenery to prevent the mealybugs from spreading to your entire collection.

2 Treat the infestation by spraying the plant with an organic insecticide or neem oil to eliminate the pests and their protective waxy coating.

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

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Powdery Mildew

This fungal pathogen presents as white, flour-like patches on the surface of the leaves. It thrives in environments with high humidity and poor air circulation around the succulent's foliage.

Common

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How to confirm: Check if the white spots appear more like a fine dusting on the leaf surface rather than distinct clumps.

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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 Neem Oil 32 oz

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2 Improve air circulation around the plant and reduce humidity by avoiding overhead watering and ensuring the foliage can dry quickly.

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

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Cottony Blight (Sclerotinia)

While less common in succulents, certain fungal pathogens can cause white, mycelium-like growth near decaying plant tissue. This usually indicates that the base of the Crassula fusca is beginning to rot due to moisture retention.

Common

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How to confirm: Inspect the base of the stem for any signs of softening or dark, mushy discoloration.

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1 Immediately remove any mushy, decaying, or heavily infected plant tissue to prevent the fungus from spreading to healthy parts of the Crassula.

2 Apply an organic fungicide to the affected area to combat the Sclerotinia growth and protect the remaining plant structure.