How to Identify and Control Pests and Diseases in your Garden
By: Linda Peppin

A number of pests and diseases are going to occur in your garden but there are ways to keep these to a minimum.

Choose good quality plants avoiding soft bulbs, lanky bedding plants and unhealthy or disease-ridden shrubs and perennials.
Cut out dead wood and remove overcrowded branches to ensure adequate ventilation.
Paint any large cuts with Arbrex to avoid infection.
Make sure the plant is suited to the site you have planned.
Rotting plants can be a source of infection and a breeding ground for slugs and woodlice; remove dead plants, rubbish and weeds.
Spray fungicides as soon as spots are seen.
When planting ensure there are no air pockets around the roots.
Feed all plants properly.
Prepare the ground prior to planting to avoid waterlogging.

These are general, every day rules. Below we examine the most common pests and diseases.

Aphids (Greenfly, Blackfly)

Attack young shoots and can spread viruses. Natural predators like ladybirds and lacewings can control Aphids so encourage them into your garden. Chemicals that can be used are Pirimicarb and Dimethoate and fatty acids.

Whitefly

Greenhouse Whitefly attack glasshouse plants like tomatoes. Cabbage Whitefly lives outside and survives on brassicas. Spray repeatedly with an insecticide containing Dimethoate or Malathion.

Caterpillars

Attack fruit, vegetables and ornamental plants. They Survive over the winter by pupating. Use Derris or Malathion to control or pick off the larvae.

Earwigs

Damage flowers (particularly Dahlias). Use traps such as flowerpots filled with straw or spray with Permethrin or Pirimiphos Methyl.

Slugs and Snails

Feed on soft young growth and are most active at night. Use slug pellets containing Methiocarb or Metaldehyde.

Eelworms

Suck out cell content from plants which discolour, distort and eventually die. Burn infected plants. Soak bulbs in hot water prior to planting and rotate crops to avoid attacks.

Red Spider Mite

Attack fruit, vegetables and ornamental plants. Yellowish mottling on upper surface of leaves with colonies living underneath the leaves covered in fine webbing. They are difficult to control but try spraying with an insecticide containing Dimethoate or Malathion. Biological control can also be used.

Bulb Scale Mites

Attach the neck of Narcissus bulbs and amaryllis. Immerse dormant bulbs in hot water for 3-4 hours to control.

Carrot Fly

A pest of carrots and parsnips. Larvae eat the roots and cause them to rot. Leaves have reddish tinge. Use a soil insecticide like pirimithos-methyl. Sew in June to avoid first generation larvae. Cover the necks of the carrots with good layer or soil.

Vine Weevil

Larvae feed on the roots of plants and you don't always know it's there until the plant dies. Use a Biological control or soil insecticide containing perimiphos-methyl.

Narcissus Fly

Flies lay eggs near the neck of bulbs, the larvae hatch out and burrow into the bulb, feeding on the inner tissue. Dig up and destroy the bulbs

Powdery Mildew

Fungi lives on surface of leaves and cause a white coating. Leaves turn yellow and drop early. Use a systemic fungicide and improve moisture retention. Remove infected parts of the plant and destroy.

Downy Mildew

Fungi lives within the tissue of the plant causing discolouration. Leaves will distort and wilt.

Improve air circulation and treat with Mancozeb.

Rust

Fungi attacks plants producing orange/brownish coloured areas on the leaves which may wither and fall early. Remove affected leaves and improve air circulation.

Wilt

Fungi enters via damaged roots causing wilting and withering foliage. Remove affected plants.

Black Spot

Fungal disease causing defoliation. Avoid excessive nitrogen, space well or spray with fungicide.

Narcissus Smoulder

Leaves wilt and collapse as they emerge. Destroy plants at first sign of infection.

Tulip Fire

Stunted, withered plants with grey, furry mould. Destroy plants at first sign of infection.

Honey Fungus

A very serious disease of woody plants and trees. Foliage turns yellowish/brown and white fungi grows underneath the bark at the base of the plant. Remove and burn the plant. Do not plant other woody plants in the same area.

Linda Peppin runs The Gardening Register which is an easy to follow, informative website covering all aspects of gardening. For more gardening related articles visit her site at http://www.gardeningregister.co.uk.

The articles on her website must not be copied or used elsewhere.

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