Found on a magnolia, and thought to have been imported into the UK, string cottony scale (Takahashia japonica) is not currently believed to pose a threat to host plants.
Characterised by its egg masses that resemble a white wrapping around the host's branches. Native to Asia the pest has spread around the world with plant trade.
Professor Nicola Spence spoke at the RHS John MacLeod lecture in 2018 about protecting the UKs plant health from the increasing threats resulting from international plant trade. Nicola warned, “there's been a dramatic increase in the number of pests and diseases arriving in the UK” and suggested we need to do more to limit new pest introduction and protect our plants.
“The sting cottony scale is the first new pest detected by the RHS in 2019. On average four are found every year but the global plant trade is exacerbating the spread of pests and diseases and gardeners need to be alert to changes and maintain good plant health” - Gerard Clover, Head of Plant Health.
The RHS is keen to hear from gardeners who find the pest in their garden so that it can build a picture of host plants in the UK and tailor advice to gardeners. Magnolias, mulberries, elders, sycamores and dogwoods are thought to be a favourite. If it is considered unbearable by gardeners, where practical, egg masses can be removed with a stiff brush and water.
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