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Hydrangea scale became established in the UK during the 1980s and has since become widespread in English gardens, it is also found in parts of Scotland and Wales.
Hydrangea scale is a sap sucking insect found on hydrangeas but can also feed on many other woody plants including Acer and Prunus. Infested plants can suffer a lack of vigour caused by the insect sucking sap from the foliage and stems. It can also lead to leaf loss.
The immature scales are difficult to see but infestations become apparent in early summer when the mature scales deposit their eggs on the stems and leaves. You may see:
Heavily infested plants should be removed and replacements planted in the autumn. Some manual removal of egg masses and adult scale can be attempted but may have a limited affect.
Control is best attempted in July when the more vulnerable scale nymphs are present. Hydrangeas can be prone to damage from sprays to the leaves, to reduce this risk avoid spraying hydrangeas in hot sunny weather or if the soil is dry.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
Hydrangea scale is a sap-sucking insect that develops on the underside of leaves on Hydrangea and other host plants.
There is one generation a year with young nymphs hatching from eggs in mid-summer and sucking sap from the undersides of leaves. In late summer the nymphs move to the stems where they overwinter before maturing in late spring. Eggs are deposited under a covering of white waxy fibres in early summer.
Beech scale Brown scaleChemical labels explained Chemicals: using a sprayer Chemicals: using safely and effectively Cushion scaleDiaspid scale Euonymus scaleFluted scaleHemispherical scale Horse chestnut scaleHydrangeaHydrangea pruningJuniper scale Mussel scaleOleander scale RHS statement on pesticides in horticulture Scale insectsScurfy rose scale Soft scale Viburnum scale Wisteria scaleWoolly vine or currant scale Yew scale
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