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Once an uncommon glasshouse problem in the UK, fluted scale now occurrs on outdoor plants in sheltered places.
Common name Fluted scaleScientific name Icerya purchasiPlants affected Citrus, Acacia, Choisya and many other mainly woody plantsMain cause A sap-sucking insectTiming Present all year round
Fluted scale is a sap-sucking insect that originates from Australasia but has become widespread in the warmer parts of the world, including the Mediterranean area. It is also sometimes known as Cottony cushion scale, but should not be confused with cushion scale or woolly vine/currant scale. In the past is was an uncommon problem heated glasshouses in the UK but since the 1990s it has become established outside in sheltered places, especially in London.
The adults are flat, oval insects, 4-5mm long and reddish brown in colour. The females are perched on the edge of white waxy mounds in which eggs are deposited. These egg mounds have a distinctive grooved or fluted appearance, which is unlike any other scale species found in the UK. The young nymphs are oval and brownish but have a white waxy coating. Adults and nymphs can be found together all year round on the stems and foliage. Frequent host plants are Citrus, Acacia and Choisya but it can also attack many other woody plants.
Fluted scale sucks sap from a wide range of trees and shrubs. Heavily infested plants lack vigour and can be killed. A black sooty mould may grow on the insect's sugary excrement.
When buying Citrus, Acacia or Choisya, check carefully to make sure they are free of infestation. If plants do become infested, this can be a difficult problem to eradicate. On small plants, look for and remove the scales and their egg mounds before eggs hatch.
In many parts of the world, an Australian ladybird known as the vedalia ladybird, Rodolia cardinalis, has been released as a biological control for fluted scale. This ladybird is not commercially available in the UK but it has been found in some parts of London. It probably arrived accidentally, along with the scale insect, on imported plants.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
Fluted scale has two or three generations a year, which overlap so both nymphs and adults can be found at the same time. The adult scales are mainly found on the stems, whereas young nymphs are mainly on the underside of leaves along the leaf veins. Each egg mound can contain several hundred eggs.
Acacia: pruningBeech scale Brown scaleChemical labels explained Chemicals: using a sprayer Chemicals: using safely and effectively Citrus: problemsCitrus and Asian longhorn beetleCushion scaleDiaspid scaleEuonymus scaleHemispherical scale Horse chestnut scaleHydrangea scaleJuniper scale MealybugMussel scaleOleander scale RHS statement on pesticides in horticulture Robinia pseudoacacia 'Frisia' problemsScale insectsScurfy rose scale Soft scale Viburnum scale Wisteria scaleWoolly vine or currant scale Yew scale
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ma schindler on 14/05/2014
I have just discovered an infestation of fluted scale on my black and redcurrants. I've just spent the last hour squashing them. The result of a mild wet winter in the Rhindda Valley. Hope my bushes survive.
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