Pests and Diseases of Woody Plants

Woody Plants

Aphids (various species)

Aphids attack young shoots and foliage of trees and shrubs. Some, such as honeysuckle aphids, viburnum aphids and beech aphids, are restricted to one host; others are less specific.

Typical symptoms: Leaves and shoots are infested with tiny insects of varying colours. Leaves may be blistered, distorted, sticky and blackened; shoot growth may be distorted. Symptoms may persist when the pests have flown.

Prevention and treatment: Predators that seek out overwintering eggs can be particularly useful. Leave colonies where they are doing no harm; they can act as a reservoir of food for predators and parasites. See Aphids as Garden Pests

Brown tail moth (Euproctis chrysorrhoea)

Brown tail moth (Euproctis chrysorrhoea) - pests and diseases of woody plants Typical symptoms: Colonies of caterpillars construct protective “tents” in branches of trees. In the summer, leaves are eaten by caterpillars.

Prevention and treatment: Prune out and burn the tents. Wear gloves and avoid any contact with the caterpillars as they can irritate the skin.

Caterpillars (various species)

Typical symptoms: Many species of caterpillars eat the leaves of most trees and shrubs.

Prevention and treatment: Pick off caterpillars as they are found or spray with derris.

Coral spot (Nectria cinnabarina)

Coral spot affects beech, Elaeagnus, magnolia and Pyracantha; also other plants.

Typical symptoms: Pink pustules on dead twigs and branches; branches may die back.

Prevention and treatment: See How to Treat Common Plant Diseases

Fireblight (Erwinia amylovora)

Hawthorn, cotoneaster, sorbus and other related trees are susceptible to fireblight.

Typical symptoms: Leaves brown or blacken; these remain on the tree, giving it the appearance of having been scorched by fire.

Prevention and treatment: See Pests and Diseases of Tree Fruit

Honey fungus (Armillaria mellea)

This disease affects birch, lilac, pines, privet, and willows; also many other woody plants.

Typical symptoms: Plants die suddenly; white fungus smelling of mushrooms is found beneath bark at or just above soil level.

Prevention and treatment: See How to Treat Common Plant Diseases

Leaf miner (various species)

This affects many woody plants, especially lilac, privet, laburnum and holly; also other plants.

Typical symptoms: Blisters or snaking “mines” are visible in leaves.

Prevention and treatment: See Pests and Diseases of Garden Flowers

Pyracantha scab (Spilocaea pyracanthae)

This disease affects many woody plants, in particular pyracantha, especially in wet seasons.

Typical symptoms: Olive-brown spots appear on leaves, which may fall early; small rough lesions grow on twigs; berries are disfigured.

Prevention and treatment: Do not grow pyracantha in damp situations. Prune out and pick off diseased leaves and twigs. Some varieties have resistance to scab.

Scale insects (various species)

Soft scale attacks greenhouse plants and woody plants in warm places, particularly bay trees, camellias and ivies.

Typical symptoms: The scales are creamy or dark brown and live on the underside of leaves, along veins. Other species attack leaves and stems of trees and shrubs; they do little harm.

Prevention and treatment: See General Garden Pests

Woolly aphids (Eriosoma lanigerum)

These attack pyracantha, cotoneaster and related plants.

Typical symptoms: Tufts of fluffy white wax are found on stems and leaves.

Prevention and treatment: See Aphids as Garden Pests

02. February 2011 by Dave Pinkney
Categories: Organic Gardening, Pests and Diseases, Plant Care | Tags: , | Comments Off on Pests and Diseases of Woody Plants


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