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Cypress aphid is one of the causes of dieback on conifer hedges. It has become an increasingly problematic on conifer hedges since the 1980s, particularly on Leyland cypress.
Cypress aphid damage
Cypress aphid is a blackish brown sap-sucking insect that infests the stems of some hedging conifers (Cupressus species especially C. macrocarpa, Thuja occidentalis, Chamaecyparis lawsoniana and x Cuprocyparis leylandii) in early summer. This often causes a gradual drying up and browning of the foliage.
There are a number of aphid pests of other conifers and aphid like adelgids can also affect these plants.
A hedge that is cared for and pruned during the growing season will be more resistant to cypress aphid damage.
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)
Damage is caused by greyish brown aphids that are active from May to November, reaching peak numbers in early to mid-summer.
Chemical labels explained
Chemicals: using a sprayer
Chemicals: using safely and effectively
Conifers: brown patches
Conifers: Pestalotiopsis disease
Currant blister aphid
Green spruce aphid
Leyland cypress: pruning
Mealy cabbage aphid
Pear bedstraw aphid
Raspberry and blackberry aphids
RHS statement on pesticides in horticulture
Rose root aphid
Rosy apple aphid
Willow bark aphid
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