It is causing brown patches on leylandii after surviving the mild winter and thriving this spring. Problems are developing, according to consultant John Adlam, who said there were not enough products on the market to kill the pest.
He said: “Some garden protection companies are withdrawing products for a range of commercial and legislative reasons, leaving fewer products that are effective. It becomes more difficult to treat some diseases and pests. It’s the same problem with box blight.”
Tenterden-based landscape gardener Ray Hancy said there were dozens of hedges in Kent he knew had been hit by cypress aphid, adding: “I’ve never seen the like of it before. The climate has started to suit it because it’s not natural to this country.”
Brian Warrington of the Evergreen Conifer Centre near Kidderminster, Worcestershire, said: “It’s a problem all over the country. I’ve heard of several fresh outbreaks. People are asking what is happening — they can’t understand why they’re getting it when it’s so wet.”
RHS head of horticultural advice Guy Barter said: “The pest is pretty bad this year and it seems very likely that strange weather conditions are responsible. The stress on trees causes brown patches.”
Consultant entomologist John Buxton said: “It’s a very virulent pest. You have to look to find it in cypress because it hides very well.”
Adlam added: “I suggest this is because of the mild winter. We have not had the normal winter kill-off. Then we had an early spring and the aphids came out early and attacked.”
East Malling Research scientist Dr Chantelle Jay said: “Responding to industry concerns, East Malling Research and RHS Wisley, with Roger Ward of Golden Grove Nursery, Lincolnshire, are currently working on an HDC-funded project (HNS 151) to determine if the conifer aphid Cinara cupressivora is a major cause of the browning seen in conifer hedges.
“Although more than one aphid species can be found on conifer hedges in the UK, this aphid is a serious plantation pest in southern and eastern Africa, but little work has been published on its biology and phenology in the UK. The aphid feeds within the hedge and it is often associated with a black sooty mould that often develops in the honeydew produced by the aphids.
“A survey has been conducted to gather information about possible links between where and how Leyland and Lawson cypress hedges are grown and managed and the incidences of browning and dieback. Hedges and plant material are also being assessed for signs of live aphids or aphid presence.”
* To report any aphid damage in your nursery or hedges, contact Dr Jean Fitzgerald at East Malling Research on 01732 843833 or email firstname.lastname@example.org.
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