Turnips are a fast-growing root vegetable grown for both their swollen roots and edible greens. They mature in 30–60 days, making them suitable for early spring and fall planting when temperatures are cool. Both the root and the leaves are usable, which gives a single sowing two harvests.
Turnips do best in cool weather and turn woody or bitter in summer heat. Sow directly into the ground; they do not transplant well due to taproot disturbance. Thin seedlings early so roots have room to size up, and keep soil consistently moist to prevent splitting and tough texture.
Flea Beetle
Small round shot-holes scattered across leaves; tiny dark beetles that jump when disturbed. Heavy feeding stunts young plants.
Use floating row covers on seedlings. Remove crop debris and weeds that harbor beetles. Apply kaolin clay or spinosad if damage is severe.
Clubroot
Swollen, distorted roots; wilting in midday heat; stunted growth and yellowing foliage. Plants recover poorly even with watering.
Remove and destroy infected plants with roots. Raise soil pH toward 7.2 with lime. Improve drainage and rotate out of brassicas for several years.
Cabbage Worm
Ragged holes in leaves and green velvety caterpillars on undersides; dark green frass collects in leaf crevices and head.
Handpick caterpillars and eggs. Apply Bacillus thuringiensis (Bt) weekly during egg-laying. Use floating row cover to exclude white cabbage moths.
White Rust
Raised white to cream-colored pustules on leaf undersides, with yellow blotches on upper surfaces. Infected tissue may swell or distort.
Remove and destroy infected leaves. Improve air circulation and avoid overhead watering. Rotate brassicas and avoid planting in previously infected soil.
Black Rot
Yellow, V-shaped lesions spreading inward from leaf margins, with blackened veins. Severe cases cause wilting and leaf drop.
Remove and destroy infected plants. Use disease-free seed, rotate brassicas on a 3-year cycle, avoid overhead watering, and keep tools and beds clean.
Alternaria blight
Brown circular spots with yellow halos on leaves; spreads rapidly in wet weather.
Remove affected leaves immediately. Water at the base only. A copper-based fungicide can help if caught early.