Turnips: Pests & Diseases
Turnips are versatile brassicas grown for quick young roots, leafy tops or winter storage types. They establish best in cool, moist conditions and are especially useful for filling gaps after early crops. Young plants attract several brassica pests, so protection from sowing makes a noticeable difference to harvest quality.
Common pests
Flea beetles are frequent on turnip seedlings, leaving peppered shot-holes that can check small plants badly. Cabbage root fly larvae tunnel roots, causing wilting, poor swelling and secondary rot. Cabbage white caterpillars can strip foliage in summer, while aphids, including mealy cabbage aphid, gather on leaf undersides. Slugs also damage germinating seed and young leaves, particularly in damp weather.
Common diseases
Club root is the principal turnip disease, producing swollen, distorted roots and yellowing, stunted foliage in acidic or infected soil. Powdery mildew forms white patches on leaves in late summer or dry spells. Downy mildew may appear as yellow marks with greyish growth underneath during cool, wet weather. Damping off can affect seedlings in cold, saturated ground, while splitting follows uneven watering rather than infection.
Prevention
Use a long rotation away from brassicas on ground with club-root history, improve drainage and raise soil pH only after a soil test and appropriate advice. Sow into firm, moist soil with generous spacing and remove brassica weeds. Apply fine mesh or fleece immediately to exclude flea beetles and cabbage root fly. Choose club-root-resistant varieties where available, maintain hygiene and clear crop residues after harvest.
Non-chemical control
Keep fine mesh or fleece over young plants, with edges well sealed against flea beetles and cabbage root fly. Hand-pick cabbage white caterpillars and slugs regularly, especially at dusk. Rub off small aphid colonies and encourage ladybirds, hoverflies and parasitic wasps with flowering companion plants. Lift and dispose of club-rooted plants, including roots, away from the compost heap, then improve drainage before future brassica crops.
What to look for
Inspect seedlings every few days after sowing for shot-holes, slug grazing and missing plants. From late spring, check leaf undersides weekly for aphids, eggs and cabbage white caterpillars. If plants wilt or fail to swell, lift one to inspect roots for fly tunnels or club-root galls. Watch foliage closely during humid weather for mildew.
Tips
Sow spring and summer types little and often for tender roots, then grow storage turnips for autumn lifting. Harvest young turnips before they become coarse. Keep soil consistently moist, particularly during dry spells, and use healthy tops quickly as they are most tender when freshly picked.
Turnips pests & diseases: frequently asked questions
What are the common pests of turnips?
Flea beetles are frequent on turnip seedlings, leaving peppered shot-holes that can check small plants badly.
What diseases affect turnips?
Club root is the principal turnip disease, producing swollen, distorted roots and yellowing, stunted foliage in acidic or infected soil.
How do I prevent pests and diseases on turnips?
Use a long rotation away from brassicas on ground with club-root history, improve drainage and raise soil pH only after a soil test and appropriate advice.
General guidance for UK home gardens, focused on prevention and non-chemical control. The RHS or a local garden centre can help with tricky cases. Page updated 18 Sep 2026.