Hydrangea macrophylla Magical Spotlight White Cottony Spots - Causes & Fixes

Jump to cause: Mealybugs Cottony Cushion Scale Powdery Mildew (Early Stage)

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Mealybugs

These small, soft-bodied insects secrete a white, waxy, cottony substance to protect themselves as they feed on the sap of the Hydrangea stems and leaf undersides. Their feeding can cause leaves to yellow or drop prematurely.

Very Common

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How to confirm: Use a magnifying glass to look for tiny, moving white insects at the leaf axils or nodes.

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1 Isolate the plant immediately to prevent the mealybugs from spreading to your other houseplants.

2 Apply an organic insecticide spray to the affected areas to kill the insects and their protective waxy coating.

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3 Gently wipe away any visible white cottony clusters from the stems and leaf undersides using a cotton swab dipped in rubbing alcohol.

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Cottony Cushion Scale

This scale insect produces a thick, white, cotton-like covering over its body. On Hydrangeas, they can cause stunted growth and the appearance of 'sooty mold' due to the honeydew they excrete.

Common

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How to confirm: Check if the white spots are stationary and feel slightly hard or bumpy underneath the waxy coating.

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1 Treat the plant with an organic insecticide/miticide spray to eliminate the scale insects and their white protective coverings.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Carefully wipe the cottony masses off the stems and leaves with a soft cloth or cotton swab dipped in rubbing alcohol to physically remove the pests.

3 Monitor the plant for sooty mold and ensure the area has good airflow to prevent further fungal growth caused by the scale's honeydew.

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Powdery Mildew (Early Stage)

While typically appearing as a dusty film, certain fungal growths in high humidity can look like tufts of white cotton on new Hydrangea foliage. This is common when air circulation around the 'Magical Spotlight' variety is poor.

Common

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How to confirm: Try wiping a leaf with a damp cloth; if the white substance wipes away easily without leaving behind insect bodies, it is likely fungal.

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1 Apply an organic fungicide to the affected foliage to stop the spread of the fungal growth.