Rutabaga

Description

Rutabaga, Brassica napus, is an herbaceous biennial in the family Brassicaceae grown primarily for its edible root. The plant is believed to be a hybrid of turnip and wild cabbage. The leaves grow from a stout swollen stem (neck) close to the ground forming the crown the plant. Rutabaga leaves are thick smooth and waxy. They are lobed and have a bluish hue. The plant produces light yellow flowers which are clustered at the top of a raceme. Unlike turnip, the flowers do not extend above the terminal buds. The taproot of the plant is is a bulbous tuber, almost perfectly round, which can be purple, white or yellow with yellow flesh. Rutabaga plants can reach in height of 30–46 cm (12–18 in) and although biennial, they are commonly grown as an annual, harvested after one growing season. Rutabaga may also be referred to as swede or yellow turnip and originates from Europe.


Uses

Rutabaga roots are usually consumed as a vegetable after cooking. The leaves are also edible and can be eaten fresh in salads or after cooking.


Propagation


Basic requirements
Rutabagas are cold hardy vegetables which can be grown early in the spring for a summer harvest or in the summer for harvesting in late fall. They prefer a fertile, well draining soil which has a pH between 6.0 and 7.0. The soil should have a loose texture for optimum root development. Rutabagas will grow best in full sun but will tolerate partial shade. The average daily temperature should fall between 10–18°C (50–65°F) for adequate growth.

Planting
Rutabagas are usually direct seeded and can be sown as soon as the soil is workable in the Spring. For a Fall harvest, sow seeds about 2 months before the first frost in your area. Prepare the soil for planting by loosening it with a fork to a depth of about 30–38 cm (12–15 in). Remove any large rocks if present. Incorporate 2–4 inches of compost into the soil prior to planting. Sow seeds by broadcasting and raking 13 mm (0.5 in) into the soil. Thin seedlings to a final spacing of 7.5–10 cm (3–4 in). Alternatively, seeds can be sown in rows spaced 30–45 cm(12–18 in) apart.

General care and maintenance
Water rutabagas evenly and keep the soil moist for optimum growth. Mulching the plants will help to conserve moisture in the soil. Pull any weeds as they appear, the soil can be cultivated down to 2.5–5.0 cm (2–3 in) when the plants are small but this should be reduced as the plants grow larger to prevent damage to delicate feeder roots.

Harvesting
Rutabaga greens can be harvested from the plant when the leaves are about 10 cm (10 in) tall. If growing for both greens and roots then only remove 2–3 leaves from each plant. Roots are ready to harvest when they reach 2.5–7.5 cm (1–3 in) in diameter. Small rutabagas can often be harvested by gently pulling from the soil by hand but larger roots in heavier soil may need gently dug up with a garden fork. Store unwashed roots in a root cellar or basement.


References

Anderson, C. R. Turnips-Rutabagas. University of Arkansas Division of Agriculture and Natural Resources. Available at: https://www.uaex.edu/publications/PDF.... [Accessed 08 April 15]. Free to access.

Sanders, D. (2001). Turnips and Rutabagas. North Carolina State University Cooperative Extension. Available at: http://content.ces.ncsu.edu/turnips-a.... [Accessed 08 April 15]. Free to access.

Undersander, D. J. Kaminski, A. R., Oelke E. A., Doll, J. D., Schulte, E. E. & Oplinger, E. S. (1992). Rutabaga. In: Alternative Field Crops Manual. University of Wisconsin-Extension, University of Minnesota Center for Alternative Plant & Animal Products and University of Minnesota Extension Service. Available at: http://content.ces.ncsu.edu/turnips-a.... [Accessed 08 April 15]. Free to access.



Common Pests and Diseases

Black rot
Xanthomonas campestris

Symptoms
Irregularly shaped dull yellow areas along leaf margins which expand to leaf midrib and create a characterstic "V-shaped" lesion; lesions may coalesce along the leaf margin to give plant a scorched appearance
Cause
Bacterium
Comments
Pathogen is spread via infected seed or by splashing water and insect movement; disease emergence favored by warm and humid conditions
Management
Primary method of controlling black rot is through the use of good sanitation practices; rotate crops to non-cruciferous crops every 2 years; plant resistant varieties; control cruciferous weed species which may act as a reservoir for bacteria; plant pathogen-free seed

Anthracnose
Colletotrichum higginisianum

Symptoms
Small circular or irregularly shaped dry spots which are gray to straw in color on leaves; a high number of spots may cause the leaf to die; lesions may coalesce to form large necrotic patches causing leaves to turn yellow and wilt; lesions may split or crack in dry centers
Cause
Fungus
Comments
Fungus overwinters on leaf debris and on related weeds; disease emergence is favored by moist, warm conditions
Management
Control of disease depends on sanitary practices; treat seeds with hot water prior to planting; rotate crops; plant in an area with good soil drainage; remove all cruciferous weeds which may act as a reservoir for the fungus

Alternaria leaf spot
Alternaria spp.

Symptoms
Small dark spots on leaves which turn brown to gray; lesions may be round or angular and may possess a purple-black margin; lesions may form concentric rings, become brittle and crack in center; dark brown elongated lesions may develop on stems and petioles
Cause
Fungus
Comments
Disease emergence favors warm, wet conditions
Management
Plant only pathogen-free seed; rotate crops; applications of appropriate fungicides control disease when present

Cercospora leaf spot (Frogeye leaf spot)
Cercospora brassicicola

Symptoms
Angular or circular green to gray spots with brown borders on leaves; plant defoliation may occur in the case of a severe infestation
Cause
Fungus
Comments
Disease emergence favors cool temperatures and wet weather
Management
Plant only certified disease-free seed; avoid overhead irrigation; rotate crops to non-brassica species for 2-3 years; apply appropriate fungicide if disease emerges

Downy mildew
Peronospora parasitica

Symptoms
Irregular yellow patches on leaves which turn light brown in color; fluffy gray growth on the undersides of the leaves
Cause
Fungus
Comments
Disease emergence favors cool temperatures; disease spreads quickly in wet conditions
Management
Remove all crop debris after harvest; rotate with non-brassicas; application of appropriate fungicides may be required if symptoms of disease are present

Wireworms
Aeolus spp.
Anchastus spp.
Melanotus spp.
Limonius spp

Symptoms
Death of seedlings; reduced stand; girdled stems and white heads; wireworm larvae can be found in soil when dug round the stem; larvae are yellow-brown, thin worms with shiny skin
Cause
Insect
Comments
Larval stage can last between 1 and 5 years depending on species
Management
Chemical control impossible in a standing crop, must be applied at preplanting or as a seed treatment; if wireworms are known to be present in soil fallow field during summer and till frequently to reduce numbers; rotate to non-host crop where possible; avoid planting susceptible crops after a wireworm infestation on cereals without either fallowing of applying appropriate pesticide

Cabbage aphid
Brevicoryne brassicaea

Symptoms
Large populations can cause stunted growth or even plant death; insects may be visible on the plant leaves and are small, grey-green in color and soft bodied and are covered with a white waxy coating; prefer to feed deep down in cabbage head and may be obscured by the leaves
Cause
Insect
Comments
Cabbage aphids feed only on cruciferous plants but may survive on related weed species
Management
If aphid population is limited to just a few leaves or shoots then the infestation can be pruned out to provide control; check transplants for aphids before planting; use tolerant varieties if available; reflective mulches such as silver colored plastic can deter aphids from feeding on plants; sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use

Root maggots
Delia spp.

Symptoms
Scars and feeding tunnels on surface of turnip; root damage may be extensive; larvae are white or white-yellow in color, reach approx. 1 cm (0.3 in) in length and taper towards the head; adult insect is a small fly which resembles a housefly
Cause
Insect
Comments
Root maggots will attack all varieties of crucuferous plants; insect overwinters as pupae in the soil
Management
If root maggots were problematic, avoid planting root crops in same area the following year; if crops are too badly damaged to harvest remove and destroy all crop debris; use of floating row covers can dramatically reduce damage to crops by preventing female flies from laying eggs - note, row covers only effective where root maggots are not already present; there are currently no pesticides registered for use on root maggots in the home garden in the USA

Flea beetles
Phyllotreta spp.

Symptoms
Small holes or pits in leaves that give the foliage a characteristic “shothole” appearance; young plants and seedlings are particularly susceptible; plant growth may be reduced; if damage is severe the plant may be killed; the pest responsible for the damage is a small (1.5–3.0 mm) dark colored beetle which jumps when disturbed; the beetles are often shiny in appearance
Cause
Insects
Comments
Younger plants are more susceptible to flea beetle damage than older ones; older plants can tolerate infestation; flea beetles may overwinter on nearby weed species, in plant debris or in the soil; insects may go through a second or third generation in one year
Management
In areas where flea beetles are a problem, floating row covers may have to be used prior to the emergence of the beetles to provide a physical barrier to protect young plants; plant seeds early to allow establishment before the beetles become a problem - mature plants are less susceptible to damage; trap crops may provide a measure of control - cruciferous plants are best; application of a thick layer of mulch may help prevent beetles reaching surface; application on diamotecoeus earth or oils such as neem oil are effective control methods for organic growers; application of insecticides containing carbaryl, spinosad, bifenthrin and permethrin can provide adequate control of beetles for up to a week but will need reapplied