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Pests, Diseases and Problems

50 common garden problems and how to deal with them, starting with the gentlest methods. Each crop's page links to the problems that affect it.

Aphids (greenfly and blackfly)

Small sap-sucking insects that cluster on soft shoot tips and leaf undersides.

Affects 69 crops

Slugs and snails

Night feeders that shred seedlings, leaves and tender roots.

Affects 67 crops

Flea beetle

Tiny jumping beetles that pepper the leaves of brassicas and salad crops with small holes.

Affects 18 crops

Caterpillars (cabbage whites and others)

Butterfly and moth larvae that chew leaves, especially on brassicas.

Affects 17 crops

Cabbage root fly

Maggots that eat the roots of brassicas and kill young plants.

Affects 9 crops

Carrot fly

Low-flying flies whose maggots tunnel into carrots, parsnips and celery roots.

Affects 4 crops

Onion fly

Maggots that eat the roots and bulbs of onions, leeks and shallots.

Affects 6 crops

Leek moth

Small caterpillars that mine the leaves and stems of leeks, onions and garlic.

Affects 3 crops

Red spider mite

Tiny mites that thrive in hot, dry conditions, especially under cover.

Affects 12 crops

Whitefly

Tiny white flies that suck sap and coat plants with sticky honeydew.

Affects 10 crops

Leaf miners

Tiny maggots that tunnel between the surfaces of leaves.

Affects 12 crops

Codling moth and plum moth

Moth larvae that burrow into apples, pears and plums, causing "maggoty" fruit.

Affects 4 crops

Pea moth

Caterpillars that eat the peas inside the pods.

Affects 1 crop

Raspberry beetle

Small beetles whose larvae spoil raspberries, loganberries and blackberries.

Affects 3 crops

Vine weevil

Beetles and grubs that eat leaves and roots, especially in pots.

Affects 4 crops

Pea and bean weevil

Small beetles that nibble neat notches from the leaf edges of peas and beans.

Affects 2 crops

Rosemary beetle

Attractive metallic beetles that eat rosemary, lavender, thyme and sage.

Affects 3 crops

Sawfly caterpillars (currant and gooseberry)

Green caterpillars that strip the leaves from gooseberry and currant bushes.

Affects 4 crops

Wasps

In late summer wasps damage ripe plums, apples and grapes.

Affects 8 crops

Big bud mite

Microscopic mites that live in blackcurrant buds and spread reversion virus.

Affects 1 crop

Powdery mildew

A white powdery coating that appears on leaves and stems in dry, warm weather.

Affects 23 crops

Downy mildew

A damp-weather disease with yellow patches above and grey-purple fuzz below the leaf.

Affects 9 crops

Clubroot

A soil-borne disease of brassicas that causes swollen, distorted roots.

Affects 12 crops

Potato and tomato blight

A rapid fungus-like disease that turns potato and tomato foliage brown and rots tubers and fruit.

Affects 3 crops

Rust

Orange or brown pustules that appear on the leaves of leeks, garlic, beans, mint and chives.

Affects 15 crops

White blister (white rust)

Raised white blisters on the leaves and stems of brassicas and some salad crops.

Affects 3 crops

Onion white rot

A soil fungus that rots the roots and bulbs of onions, garlic and leeks.

Affects 6 crops

Honey fungus

A root fungus that kills trees, shrubs and fruit bushes.

Affects 4 crops

Grey mould (botrytis)

A fluffy grey mould that attacks fruit, flowers and soft stems in damp conditions.

Affects 9 crops

Leaf spot

Brown or black spots on leaves caused by fungi or bacteria.

Affects 8 crops

Brown rot

A fungus that rots apples, pears, plums and cherries on the tree and in store.

Affects 3 crops

Bacterial canker and coral spot

Diseases of stone fruit and trees that cause oozing, die-back and dead branches.

Affects 6 crops

Silver leaf

A fungus that gives leaves a silvery sheen and kills branches of plums and cherries.

Affects 3 crops

Peach leaf curl

A fungus that blisters and curls the leaves of peaches, nectarines and almonds.

Affects 2 crops

Fireblight

A bacterial disease that scorches blossom and shoots on pears, apples and quinces.

Affects 2 crops

Apple and pear scab

A fungus that causes dark scabby spots on leaves and fruit.

Affects 2 crops

Plant viruses

Viruses that cause mottled, distorted leaves and stunted plants, often spread by aphids.

Affects 7 crops

Damping off

A fungal disease that rots seedlings at the base so they collapse.

Affects 1 crop

Root and crown rot

Rot caused by waterlogged soil that kills roots and plants.

Affects 13 crops

Birds and pigeons

Birds strip brassicas, peck fruit and pull up seedlings and onion sets.

Affects 26 crops

Mice, squirrels and badgers

Mammals that dig up seeds, steal nuts and raid sweetcorn.

Affects 3 crops

Growing problem

Bolting

Plants run to flower and seed too early, so leaves and roots turn tough or bitter.

Affects 20 crops

Growing problem

Frost and cold damage

Late frosts and cold snaps blacken tender growth and ruin blossom.

Affects 17 crops

Growing problem

Blossom end rot

A black, sunken patch at the base of tomatoes, peppers and courgettes.

Affects 2 crops

Growing problem

Fruit splitting

Tomatoes, plums, cherries and other fruit crack after a dry spell followed by heavy water.

Affects 3 crops

Growing problem

Poor pollination

Flowers appear but little or no fruit sets.

Affects 5 crops

Growing problem

Wind damage

Strong winds snap stems, shred leaves and dry out plants.

Affects 3 crops

Growing problem

Yellow leaves from high soil pH (chlorosis)

Leaves turn yellow between the veins when plants cannot take up iron.

Affects 1 crop

Growing problem

Plants that spread and self-seed

Some herbs and vegetables spread by runners, roots or seed and can take over a bed.

Affects 11 crops

Growing problem

Drought and irregular watering

Dry spells cause wilting, flower and fruit drop, bolting and poor crops.

Affects 8 crops

Advice here favours prevention, barriers, hand-picking and natural predators. If you choose to use a product, make sure it is approved for use in UK home gardens, follow the label exactly, and avoid spraying open flowers so bees are not harmed.