Brassica napus (Napobrassica group) and Brassica rapa (Rapifera Group)
Last revised February 15, 2010
Turnips with high Potassium (left) and low Potassium (right). Photo credit: Bill Mansour, Oregon State University
VARIETIES (approximately 60-80 days).
Improved Laurentian (fresh market), American Purple Top (fresh market and processing). For trial: Magres - used for very early production from modular transplants in Ireland and the U.K., tolerant to bolting. By using modular transplants, root shape is changed. An attractive round root shape is produced; Marian - research from Europe indicates this variety is tolerant to club root.
Purple Top White Globe, Royal Globe II, Royal Crown, Shogoin Topper; Tokyo Cross and White Lady (latter two all white). Club-root resistant for trial: York. Others for trial: Fuku Komache, Seven Top
Turnips for Greens
Shogoin, Seven Top, Topper, All Top. For trial: Fortress (also see file Turnip Greens).
SEED AND SEED TREATMENTS
Rutabaga and turnip seed numbers approximately 12,000 per ounce. Use hot-water treated seed and fungicide treat seed to protect against several serious seedborne diseases. Hot water seed treatments are very specific (122 F exactly, for 25 to 30 minutes; the wet seed is then quickly cooled and dried). The seed treatments are best done by the seed company, and can usually be provided upon request.
Use deep loam or sandy loam soil types that have good drainage. It is desirable to have a good amount of organic matter in the soil as well. Soils with good drainage are essential for fall and winter- harvested crops.
Spring crop: Seed as early as possible in W. Oregon
Summer crop: Late May or early June
Fall crop : July 20 to August 1
Use fungicide seed treatment. Rutabaga spacing is 16-20 inches between rows and 3-4 inches within the row. Use 1-2 lb of seed per acre. Space turnip rows 1-3 feet apart and plants within the row 2-6 inches apart. Turnip seed is easy to precision plant and germinates readily. No pelleting is necessary with precision planters. When these planters are used, adjust the seeding rate considering plant stand desired, seed count/lb, and germination percentage
For the most current advice, see Nutrient Management for Sustainable Vegetable Cropping Systems in Western Oregon, available as a free download from the OSU Extension Catalog
The following recommendations are general. It is advisable to submit a soil sample for testing for each field to be planted.
If manure is available, apply the year before and not in the year of seeding. At time of seeding, band the following two inches to the side and two inches beneath the seed row:
Nitrogen: 50-75 (N) lb/acre
Phosphorus: 100-150 (P2O5) lb/acre
Potassium: 50-150 (K2O) lb/acre
Boron: broadcast and disc in 2-4 (B) lb/acre before planting. If additional boron is needed, use Solubor or Borospray at 0.5 to 1 lb/acre when roots are one inch in diameter.
Sulfur: 15-25 (S) lb/acre
Apply water uniformly for tender growth and maximum availability of nutrients. These crops may require from 8 to 12 inches of water depending on planting date, seasonal variation, and variety.
Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.
HARVESTING, HANDLING, AND STORAGE
The University of California-Davis has a file on Minimal Processing of Fresh Vegetables that discusses film wrapping and other topics.
Harvest will be approximately 90-100 days from seeding depending on planting date.
Fresh market: Harvest by hand pulling or by machine when the soil is comparatively dry so that a minimum of dirt adheres to the roots.
Processing: Mechanical methods used for harvesting beets and carrots are satisfactory where turnips and rutabagas are grown for processing. Handle roots with care during harvest to reduce injury and rots during storage.
Yields are approximately 300 cwt/acre.
STORAGE (Quoted or modified from USDA Ag. Handbook 66 and other sources)
Store rutabagas at 32 F and 98 to 100% relative humidity, turnips at 32 F and 95% RH. Rutabagas and topped turnips require the same storage conditions as topped carrots and should keep satisfactorily for 4 to 6 months. Roots lose moisture and shrivel readily if not stored under high humidity conditions. The optimum humidity is 98 to 100% or as close to saturation as possible. Turnips and rutabagas in good condition can be expected to keep 4 to 5 months at 32 F and high relative humidity. Canadian research has shown that, as compared with rutabagas stored at 90 to 95% relative humidity, those stored at higher humidities had either less or about the same amount of decay, lost considerably less moisture, remained firmer, and had better color. Roots should be stored in slatted crates or bins, and good air circulation around the containers should be maintained.
Waxing is not recommended for turnips and rutabagas before extended storage; it could be harmful. However, they are often hot-waxed with paraffin just before being marketed to improve appearance and prevent undue moisture loss and consequent shriveling. Too heavy a wax coating may cause severe injury from internal breakdown due to suboxidation.
Rutabagas can stand slight freezing without injury. Severe freezing causes water-soaking and light browning of the flesh, and fermentation. Rough handling of the roots during harvesting and during filling of bins may increase storage losses. The growth regulator maleic hydrazide, applied before harvest, is effective in preventing sprouting in storage.
Packaging turnips in perforated plastic bags helps keep the humidity high around the roots during marketing and reduces shriveling. Pre-peeled rutabagas packaged in consumer film bags keep in good condition for 3 weeks at 32 F.
Rutabagas are commonly packaged in 25-lb bags and cartons, or 50-lb sacks and cartons. Topped turnips are commonly packaged in 25-lb bags; 50-lb film and mesh bags; or 24-lb cartons holding 24 film bags, 1 lb each.