Bartlett Tree Experts: Holly

Ilex aquifolium

All parts of the plant are toxic to humans if consumed but the berries provide a food source for birds. This evergreen plant has religious significance to Christians, to whom it represents Christ, and to Druids, who believe it protects against evil spirits. The timber is prized for its white colour but is hard to prepare and work. The young foliage was once collected and dried in summer to feed animals through the winter.

Culture
Concerns
Management

Culture for Holly

Holly is often found as a shrub or in hedges but can form a small tree in open conditions. Requires full sun or partial shade and well drained soil. Tolerates chalk soils. Plants are separately male and female; males produce flowers but no fruit.

Concerns about Holly

Holly leaf blight is a species of Phytophthora. This pathogen lives in the soil, attacking roots first and then moving into the main stem, causing dieback. Black blotches form on the leaves and smaller stems. In hedges a characteristic arc of yellowing which then dies back is often visible. Phytophthora attacks are often associated with waterlogging as this stresses the plant, making it susceptible and helps the pathogen move to roots. Common insect pests are: aphids, scale, and holly leaf miner.

Management Practices for Holly

Treat Phytophthora using 'Subdue' and applications of potassium phosphite. 'Serenade' is a biological control based on the soil bacterium Bacillus subtilis, which can be combined with phosphite as a soil drench and alternated with 'Subdue'. Check for aphids (curling leaves and honeydew), scale (adult scales and honeydew), holly leaf miner (yellowish blotch like galleries on the upper surface of the leaves). In any case of pest/disease, check for sources of abiotic stress that can be mitigated. A treatment plan of 3 4 appropriate sprays at regular intervals throughout the active growing season should be used.