Conifer hedge is browned off

Q: My conifer hedge is showing signs of discoloration, in patches. It is 5m (16ft) high and 30m (100ft) long.


A: This is most likely caused by cypress aphid, an insect that lives on conifers and sucks the sap from the foliage and stems so that they turn brown and die. It is most severe on closely clipped hedges rather than loose, natural screens.
The brown patches are unlikely to recover and they should be cut out, the surrounding, green growth woven in to fill the gaps.
You could also spray the hedge with a systemic insecticide to kill the pest, ideally in late March or April.