Is foliage dieback in Leyland cypress caused by an aphid Cinara cupressivora?

RHS project team
Dr Jean Fitzgerald, East Malling Research
Dr Tijana Blanusa, Rachael Tanner RHS
Start date
31/01/2006 14:44:05
End date
31/01/2008 14:44:09

Leyland cypress, aphid, dieback, browning, hedge, trimming

The problem

Leyland and Lawson cypress are extensively used to make quick growing hedges, but regular trimming of the hedges is needed to avoid excessive growth. Brown patches (dieback) are becoming more common on trimmed hedges. Feeding damage by conifer aphids can cause browning on conifers, but it is uncertain if aphids are responsible for most of the damage seen.


To survey the relationship between incidences of dieback in Leyland and plants’ growing environment and style of maintenance.

To understand whether the attack of cypress aphid, Cinara cupresivora, is the primary cause of foliage dieback in Leyland hedges.

Benefits to gardeners

The findings of this project will provide answers on how the maintenance of the Leyland hedges can be optimised to decrease the likelihood of cypress dieback appearing and spreading.

Advisory information

Read more on Conifers: brown patches

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