Vegetable garden pests and diseases

Healthy plants are much more resistant to pests and diseases than unhealthy ones which have been starved, forced or grown in overcrowded conditions.

Organic Control

Attract predators into your garden so that they will do the work for you.

– Birds eat grubs, caterpillars, slugs and aphids. Attract them with bird baths and nesting boxes.

– Bats come out at dusk to feed on aphids, cutworm moths, craneflies and other insects.

– Frogs and toads eat slugs, woodlice and other small insects. A garden pond will encourage them and will also appeal to another slug-eater, the slow worm.

– Hedgehogs will remove slugs, cutworms, millipedes, wireworms and woodlice for you. Give them an undisturbed wild corner with a pile of rotting logs, leaves and a tree stump where they can hibernate.

– Hoverflies, which look like slim wasps, lay their eggs in colonies of aphids on which the larvae feed. They are attracted to bright, open flowers like marigolds.

– Ladybirds and their grey larvae devour aphids. Grow a wide selection of plants to attract them.

– Lacewing larvae eat aphids in large quantities. They lay their eggs on the undersides of leaves.

– Ground beetles hide under leaves during the day. At night they eat eelworms, cutworms, leather jackets, insect eggs and larvae. Ground cover plants, dense vegetation and organic mulch will all attract them.

– Centipedes feed on small insects and slugs and, like ground beetles, need ground cover.

Organic control starts with physically removing any pests you find. When digging, look out for the fat, creamy coloured leatherjacket and squash it. Check plants for grey mould or powdery mildew and remove and burn any infected leaves or shoots. Remove aphids by hand or by spraying with a jet of water. Use an insecticidal soap to spray badly infected plants. Remove caterpillars by hand and drop into paraffin. Remove eggs laid by moths and butterflies on plants, especially cabbages.

Large slugs will not harm living plants — it is the small black and brown slugs that attack growing plants. Protect small plants with cut-off plastic bottles pushed into the ground. Surround larger plants with lime or soot, which slugs don’t like. Collect slugs and snails at night, and drop into paraffin.

In late summer and autumn millipedes tunnel into potatoes and other root crops. A healthy soil with deep dug beds and plenty of manure will help to keep them at bay. During the day cutworms eat through the base of a plant and cut it off. Weed to reduce the risk of infestation and hoe around the plant searching for the grubs, as they live just below the soil. Drown in paraffin. Wireworms will be attracted by a potato, carrot or split cabbage stalk pushed into the ground. Fix on the end of a stick, then periodically remove the stick and bait and destroy the worms.

Sticky traps can be used to catch flea beetles and whitefly. Coat one side of a small piece of wood with heavy grease. Pass the board, grease side down, just over the top of infested plants. The flea beetles will jump up and stick to it. Hang up a grease-coated piece of yellow card to trap whitefly.

Chemical Control

If you have a major pest or disease problem you may have to use chemicals. Choose the less toxic plant-based insecticides such as insecticidal soap, pyrethrum, derris, quassia and copper fungicide and follow the manufacturer’s instructions closely. Spray on a windless evening when pollinating insects are no longer around.

Tips on maintaining a healthy garden

o Improve your soil, and continue to dig and feed it well. A healthy soil will grow disease- resistant plants.

o Crop rotation helps to prevent the build-up of some soil-hased pests and diseases.

o Remove rotting plants and weeds, which attract pests. Burn diseased vegetation.

o Sow seeds thinly anti thin early. Over crowding encourages disease.

o Harden plants off completely by placing outside for gradually longer periods before phinting out.

o Plants that grow steadily are much more healthy than those that have a setback, Water when necessary, feed regularly and mulch to retain moisture.

o Damaged plants attract pests and disease so handle gently and hoe with care.

o Protect fragile plants from wind with a shield of larger more robust varieties.

o Act fast to remove aphids as these may he carrying virus diseases.