Hydrangea macrophylla Magical Snowdome White Cottony Spots - Causes & Fixes

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Mealybugs

These small, soft-bodied insects secrete a white, waxy, cottony substance to protect themselves while feeding on the sap of the Hydrangea stems and leaf undersides.

Very Common

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How to confirm: Inspect the nodes and leaf axils for tiny, moving white insects or sticky residue (honeydew) on the leaves.

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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.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

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3 Gently wipe away any visible white cottony clusters using a cotton swab dipped in isopropyl alcohol to remove the pests manually.

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Cottony Scale

Similar to mealybugs, these pests produce a white, fluffy covering that can appear as cottony patches on the woody stems of the Hydrangea.

Common

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How to confirm: Check if the white spots are firmly attached to the stem and do not move when poked with a toothpick.

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1 Treat the affected stems with an organic insecticide 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 Manually remove visible cottony patches using a cotton swab dipped in isopropyl alcohol to prevent further infestation spread.

3 Inspect surrounding plants and the undersides of leaves to ensure no other pests are hiding in the foliage.

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Powdery Mildew (Early Stage)

While typically appearing as a fine dust, high humidity can cause fungal colonies to clump, resembling white patches on the surface of the foliage.

Common

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How to confirm: Check if the white substance can be easily rubbed off with your finger and if the underlying leaf tissue appears chlorotic.

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1 Apply an organic fungicide to the affected leaves to stop the spread of fungal colonies.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

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2 Improve air circulation around the plant and reduce humidity by pruning crowded foliage.

3 Remove and dispose of any heavily infected leaves to prevent spores from spreading to healthy tissue.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

$13

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Sap/Residue from Aphids

Aggregations of aphids feeding on new growth can sometimes trap environmental debris or secrete honeydew that collects dust, creating a white, fuzzy appearance.

Common

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How to confirm: Look for small, green or black insects clustered on the tender new flower buds and leaf tips.

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shopping_cart Recommended Products

1 Spray the plant thoroughly with an organic insecticide to eliminate the aphid population and remove the sticky residue.

Bonide Captain Jack's Neem Oil 32 oz

0.9 L • 1 pcs • Organic

$10

In Stock

2 Wipe the affected leaves with a soft, damp cloth to clean off the accumulated honeydew and debris.

3 Monitor the new growth regularly using a moisture meter to ensure the plant remains hydrated, as aphid infestations can stress the plant's water uptake.