Cypress aphid is one of the causes of dieback on conifer hedges. It has become an increasingly damaging pest on conifer
hedges since the 1980s, particularly on Leyland cypress.
Yellowing shoots in summer; by late
summer many of these will be brown and dead.
On clipped hedges the dieback can be
quite pronounced, with the lower parts more severely affected than the top.
A black powdery coating of sooty mould may develop on the stems and
Damaged hedges can recover but it is
likely to be a slow process.
Spray in early summer to prevent damage
Suitable products contain thiacloprid
(e.g. Bayer Provado Ultimate Bug Killer Concentrate) or acetamiprid (e.g.
Bug Clear Ultra) .
It is often difficult to spray large
dense hedges thoroughly, and in years when the aphid is abundant, some damage
will occur .