Plants - Trees and Shrubs

Junipers revisited

Hardy and handsome, these modern cultivars are a far cry from those old foundation-plant horrors

Twig and Tip Blight
Symptoms: Dieback of shoot tips and browning of needles caused by fungus—most evident during periods of warm, wet weather
Controls: Provide good air circulation; avoid excess watering. Promptly remove infected branches
Most susceptible: Juniperus virginiana

Apple Cedar Rust 
Symptoms: Hard, brown, five-centimetre galls form on branches in summer, which produce an orange, jelly-like substance in spring
Controls: Prune out galls as they form; avoid planting apples or crabapples near susceptible junipers
Most susceptible: J. scopulorum and J. virginiana, especially upright forms

Phytophthora root rot
Symptoms: This soil-borne fungus kills juniper roots and causes sudden death of plant
Controls: On a poorly drained site with heavy clay soil, raised beds can help minimize infection
Most susceptible: J. horizontalis

Symptoms: Moth larvae form carrot-shaped, silken “bags” from which pests feed on needles
Controls: Remove bags or spray with Bt (Bacillus thuringiensis)
Most susceptible: Upright forms 

Spruce spider mite
Symptoms: Yellow speckling, followed by browning of needles; heavy infestations indicated by fine webbing over infected branches
Controls: This sap-sucking, nearly microscopic pest cannot be easily controlled without chemical intervention such as insecticidal soaps and dormant oils
Most susceptible: All species

Juniper scale
Symptoms: Hard, brown lumps that look like minute tortoise shells on stems and leaves
Controls: Dormant oil applied in spring can help keep this scale insect in check
Most susceptible: All species

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