TYPES, VARIETIES & CUTS
Both the root and leaves (or greens) of turnips are edible, with the latter enjoying increased popularity. Most turnips grown for fresh consumption produce small root globes, while larger types are planted and harvested for livestock feed. Exterior color is usually white, often tinged with scarlet or purple. Internal flesh is either white or yellow and is cooked like other root vegetables such as potatoes, beets, or rutabagas. A rutabaga is a cross between a turnip and cabbage.
Common root varieties include Golden Ball, Purple Top, Just Right, Orange Jelly, Royal Grown, Royal Globe, Tokyo Cross, White Egg, White Lady, and Yellow Globe. Alamo, All Top, Appin, Seven Top, Shogoin, and Topper are harvested for their greens.
References: Purdue University, Texas A&M AgriLife Extension, University of Illinois Extension, Washington State University.
PESTS & DISEASE
Red turnip beetles move in bulk and feed in colonies underneath turnip leaves.
Adults are bright red with black patches on the head and three black lines on the elytra, and are .25 inches long. Larvae are orange to black. Signs of damage include curled leaves and an overall yellow appearance on the plant.
The flea beetle feeds on the leaves of a turnip, causing a loss of photosynthetic components within the leaf. Adults will jump when disturbed. Signs of damage include tiny shot holes in foliage.
The imported cabbageworm will use turnip foliage as a nest to deposit its eggs. Adult moths are white, have three or four black spots on the wings, and have a wingspread of 2 inches. Larvae are small, velvety green with a slender orange stripe down the middle of the back, and are 1.25 inches long.
Vegetable weevils feed on the root source of a turnip, gorging on nutrients intended for the crop. Adult weevils are grayish with a V-shaped marking across the wing covers, and are a third of an inch. Larvae are cream-colored. Signs of damage include wilting.
Black rot affects the above-ground portion of the crop but may also affect the roots. Roots which are affected are known to develop dry rot. Signs of this disease include dwarfing of young seedlings, and lower leaf drop. A V-shaped pattern will form on the leaves, and as the disease progresses to the midrib of the leaf it causes the veins to turn black, resulting in the infection portion becoming brown and dry.
Root knot nematodes invade the root portion of the crop causing infected roots to swell at the invasion point and develop knot gall. Above-ground symptoms include decreasing growth, and wilting yellow leaves. The plant may die prematurely.
Clubroot is one of the most serious soilborne diseases, especially detrimental in soils which are acidic. As soil temperatures rise the disease becomes more aggressive. Disease offspring known as zoospores enter into the plant by its roots, through either parasitic wounds or mechanical wounds. A club-like or knot-like structure is formed at the roots where extreme cell malformation has occurred. Symptoms appear as continual wilting then recovery, and eventually the plant dies.
Fusarium wilt is a seedborne and soilborne fungus that is common if soil temperature is warm. The main symptom of the disease is a vascular discoloration in the crown area. Other symptoms include pale green and leafy margins, and a rolling of leaves inward as the plant wilts and dies.
Downy mildew penetrates the vegetative growth between leaf cells as the disease spreads. Disproportionate, purple spots begin developing on leaves and stems, becoming yellow-brown. Mildew forms and grows under the leaf surface. Extremely moist climate and temperatures between 50 and 60°F can encourage this disease.
Black leg lives in the seed and infected plant debris. Infected seeds germinate, causing a fungus to grow quickly, infecting the seedlings, causing lesions, and stunting overall growth.
Turnip yellow mosaic is a virus transmitted by over fifty different species of aphids. Symptoms of this virus include black necrotic spots, leaf distortion, stunting, mosaics, and mottling.