Cotyledon tomentosa White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Powdery Mildew Cottony Blight (Sclerotinia)

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Mealybugs

These small, soft-bodied insects secrete a white, waxy, cottony substance to protect themselves. They tend to hide in the crevices between the fleshy leaves of the Cotyledon tomentosa, sucking the sap and weakening the plant.

Very Common

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How to confirm: Use a magnifying glass to look for tiny moving insects or white clusters at the base of the leaves.

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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 visible white cottony masses from the crevices of the leaves.

3 Apply an organic insecticide spray to the entire plant, ensuring you coat the undersides of leaves and all crevices to eliminate remaining insects and larvae.

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Powdery Mildew

This fungal disease manifests as a white, flour-like coating on the leaf surfaces. It thrives in high humidity and poor air circulation, which can be problematic for succulents kept in enclosed spaces.

Common

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How to confirm: Check if the white spots can be wiped off easily with a damp cloth without damaging the plant tissue.

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

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2 Improve air circulation around the plant and reduce humidity by avoiding overwatering and ensuring the plant is not in an enclosed, stagnant space.

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

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Cottony Blight (Sclerotinia)

While less common in succulents, certain fungal pathogens can produce white, mycelium-like growth on decaying organic matter or leaf bases. This is usually accompanied by soft, rotting tissue.

Common

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How to confirm: Inspect the base of the leaves to see if the 'cotton' is accompanied by mushy, dark, or translucent patches.

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1 Immediately remove and discard any leaves or plant parts showing soft, rotting tissue or white fungal growth to prevent the spread of the pathogen.

2 Apply an organic fungicide to the affected area and surrounding healthy tissue to control the fungal spread.