Geranium molle White Cottony Spots - Causes & Fixes

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

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Mealybugs

These small insects secrete a white, waxy, cotton-like substance to protect themselves while feeding on the sap of Geranium molle. They often congregate in the crevices of leaf axils and tender new growth.

Very Common

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How to confirm: Use a magnifying glass to look for tiny, slow-moving insects underneath the leaves or near the stems.

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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 to kill the insects and remove the waxy coating.

Bonide Captain Jack's Neem Oil 32 oz

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

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Powdery Mildew

This fungal disease manifests as white, flour-like patches on the surface of the foliage. It thrives in high humidity and poor air circulation, which is common in dense Geranium molle plantings.

Very Common

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How to confirm: Check if the white spots look like a dusty coating that can be rubbed off the leaf surface with your finger.

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1 Apply an organic fungicide to the affected foliage to eliminate the fungal spores and prevent further spread.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

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2 Prune and dispose of heavily infected leaves to reduce the fungal load and improve airflow within the plant canopy.

3 Increase air circulation around the plant and avoid overhead watering to keep the foliage dry and reduce humidity.

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Cottony Blight (Sclerotinia)

While less common as a surface symptom, certain fungal pathogens can produce white mycelium that looks like cotton around the base or stems of the plant. This can eventually lead to stem rot in soft-tissued perennials like cranesbill.

Common

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How to confirm: Inspect the base of the stems for any signs of softening, browning, or dark sclerotia (small black structures).

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1 Remove and discard all heavily affected stems and plant debris to prevent the fungal mycelium from spreading to healthy tissue.

2 Apply a fungicide to the base of the plant and surrounding soil to control the spread of the blight.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

3 Improve air circulation around the plant and ensure the soil is not staying excessively wet, which can be monitored using a moisture meter.