Safflower (Carthamus tinctorius L.) is an annual, broadleaf oilseed crop adapted chiefly to the small-grain production areas of the western Great Plains. Evaluations of safflower in the Great Plains states began in 1925, but the seed had an oil content that was too low for profitable oil extraction. In the following years the Nebraska Agricultural Experiment Station developed varieties with about 35% oil compared to older varieties with less than 30%. Commercial production became concentrated in western Nebraska and eastern Colorado, but is now located in several Western states and Canadian Prairie provinces. California grows approximately 50% of the safflower in the U.S.A., while North Dakota and Montana, grow most of the remaining domestic production. South Dakota, Idaho, Colorado, and Arizona also produce safflower, but with much smaller acreages.
There are two types of safflower varieties, the type that produces oil which is high in monounsaturated fatty acids (oleic acid), and those with high concentrations of polyunsaturated fatty acids (linoleic acid). Either type of safflower raised in the Northern Great Plains is very low in saturated fatty acids when compared to other vegetable oils. Only the linoleic safflower is being grown commercially in the Upper Midwest. Varieties with a high content of oleic acid may soon be grown more widely.
Safflower was originally grown for the flowers that were used in making red and yellow dyes for clothing and food preparation. Today this crop supplies oil, meal, birdseed, and foots (residue from oil processing) for the food and industrial products markets, although this crop is now primarily grown for the oil. The oil in linoleic safflower contains nearly 75% linoleic acid, which is considerably higher than corn, soybean, cottonseed, peanut or olive oils. This type of safflower is used primarily for edible oil products such as salad oils and soft margarines. Researchers disagree on whether oils high in polyunsaturated acids, like linoleic acid, help decrease blood cholesterol and the related heart and circulatory problems. Nonetheless, it is considered a “high quality” edible oil and public concern about this topic made safflower an important crop for vegetable oil.
Varieties that are high in oleic acid may serve as a heat-stable, but expensive cooking oil used to fry potato chips and french fries. As an industrial oil, it is considered a drying or semidrying oil that is used in manufacturing paints and other surface coatings. The oil is light in color and will not yellow with aging, hence it is used in white and light-colored paints. This oil can also be used as a diesel fuel substitute, but like most vegetable oils, is currently too expensive for this use. The meal that remains after oil extraction is used as a protein supplement for livestock. The meal usually contains about 24% protein and much fiber. Decorticated meal (most of hulls removed) has about 40% protein with a reduced fiber content. Foots are used to manufacture soap. The birdseed industry buys a small portion of the seed production. Sheep and cattle can graze succulent safflower and stubble fields after harvest.
Safflower is an annual species in the same plant family as sunflower. This crop is adapted to dryland or irrigated cropping systems. Each seed germinates and produces a central stem that does not elongate for two to three weeks, and develops leaves near the ground in a rosette, similar to a young thistle. The slow growth of seedlings in early spring often results in a weedy crop. The strong central stems, with variable numbers of branches, grow to between 12 to 36 in. depending on environmental conditions. Safflower can compensate for hail damage with little yield loss once branches have developed. This crop is more drought tolerant than small grains since it has a taproot that can grow to 8 to 10 ft. if subsoil temperature and moisture allow. Stiff spines develop on leaf margins of most varieties at about the flower bud stage and make it difficult to walk through the fields. Branches usually produce one to five flower heads. Flower heads, about one inch in diameter, are usually yellow or orange in color, although some varieties have red or white flowers. Flower buds form in late June and flowering starts in mid- to late July, and continues for two to three weeks depending on environmental conditions, stand density, and varietal differences. Each flower head produces 15 to 30 seeds with a seed oil content usually between 30 to 45%. Seeds are enclosed in the head at maturity, which prevents shattering before harvest and delays somewhat the feeding loss from birds. Seeds usually mature in September, which is about four weeks after flowering ends. This crop usually needs 110 to 140 days to mature in the Upper Midwest.
((Economics of Production and Markets))
Safflower gives farmers cash income and may increase flexibility in dryland crop rotations. Safflower is grown usually under contract on a per acre basis. That is, the grower buys seed from the contracting firm and agrees to sell the entire crop for a set price. Contracts are negotiated before spring planting. Farmers are paid based on percentage of oil in the seed and/or test weight at an 8% moisture level. A recent contract price for safflower in western North Dakota and northeastern Montana was an average of 90/lb within a range of 8 to 10 cents/lb. Growers were given a 2% price bonus for each percent oil content greater than 36%. Birdseed contracts have slightly higher prices than safflower raised for oilseed. Contracts should also cover payment provision, storage payments and provisions, bonuses and discounts for moisture content and dockage, freight charges, and a clause to cover a crop disaster if it is damaged by environmental conditions, insects, or diseases. Due to recent changes in the Federal farm program, contracts are less common, and marketing loans are encouraging production for the cash or open market. Good seed production requires hot, dry conditions during the periods of flowering, seed set, and maturation. Cool summer temperatures in parts of Minnesota and Wisconsin at these times may cause poor yields. The effect of high humidity and rainfall in promoting disease problems, such as Alternaria leaf spot, also make this crop questionable for production in this area of the Upper Midwest. Other minor oilseed crops may be more economically viable in most parts of Minnesota and Wisconsin.
Safflower production is not recommended for areas with more than 15 in. of annual precipitation or growing seasons with fewer than 120 frost-free days and less than 2,200 growing degree days. Temperatures as low as 20Â°F are tolerated by plants while in the rosette stage, but safflower is very sensitive to frost injury after stem elongation until crop maturity. This crop does best in areas with warm temperatures and sunny, dry conditions during the flowering and seed-filling periods. Yields are lower under humid or rainy conditions since seed set is reduced and the occurrence of leaf spot and head rot diseases increases. Consequently, this crop is adapted to semiarid regions. Most areas of Minnesota and Wisconsin are not well suited for safflower.
Deep, fertile, well-drained soils that have a high waterholding capacity and high level of stored moisture are ideal for safflower. This crop is also productive on coarse-textured soils with low water-holding capacity when adequate rainfall or moisture distribution is present. Soils that crust easily can prevent good stand establishment. High levels of soil salinity can decrease the frequency of seed germination and lower seed yield and oil content. Safflower has approximately the same tolerance to soil salinity as barley.
- SEED PREPARATION
Seed should be treated with a registered fungicide to reduce losses due to seed-borne rust and damping-off organisms. Germination will not begin until soil temperature exceeds 40Â°F.
- CULTURAL PRACTICES
Safflower gives farmers some options in a dryland crop rotation with respect to weed and disease control, and in using soil moisture available to its deep taproot. This crop is usually grown in rotation with small grains or fallow. Safflower can be severely injured by soil residues of broadleaf herbicides that were used on small grains earlier in the rotation. Caution must be used when growing safflower after small grains. Safflower should not follow safflower in rotation or in close rotation with crops susceptible to Sclerotinia head rot (white mold), such as sunflower, mustard, canola (oilseed rape), or dry bean. A crop following safflower should be grown only if there has been a significant recharge of soil moisture. Very little crop residue remains after harvesting safflower. Therefore, reduced tillage or chemical fallow after safflower may help reduce wind and water erosion of the soil. The production practices and equipment needed for safflower are similar to those used for small grains. ((Seedbed Preparation)) Volunteer small grain may be a problem when safflower follows small grain. Fall tillage and rains should reduce this problem. A moist, firm seedbed should be prepared to help establish a good stand.
Safflower is usually planted in late April or early May. This crop may not mature if planted after mid-May. Planting dates recommended for North Dakota are between April 20 to May 10. Seedlings emerge in 8 to 15 days. Sowing the crop after mid-May increases the possibility of lower seed yield and quality due to injury from fall frost and disease. Late planting usually results in shorter plants, less branching, and lower seed yield and oil content, even if damage from frost or disease does not occur.
((Method and Rate of Seeding))
Use a grain drill to plant seed at depths of 1 to 1 1/2 in. at a rate of 20 to 25 lb/acre. A shallow planting depth promotes a uniform emergence that is important when planting early. Dryland rows are usually spaced at 6 to 7 in. with about 6 plants/ft2; however, rows spaced up to 14 in. apart are sometimes used. Wider row spacing may decrease disease incidence, but can promote more weed competition, less branching, delayed maturity and lower oil content of seed. Seeding rates for irrigated crops should be 25 to 35 lb/acre. Seed is similar in size to barley and weighs about 38 lb/bushel. Drill settings for planting safflower usually agree with settings for similar seeding rates of barley.
Soil tests are necessary to correctly determine whether any additional soil nutrients are required. The amount of fertilizer needed for safflower production depends on the yield goal, its position in the rotation, and the other crops used in the rotation. Safflower has deeper roots than small grains or flax, and can effectively use nitrogen remaining in the soil from previous crops to a depth of 7 ft. As a result, soil samples should be collected at depths from 2 to 4 ft to increase the accuracy of fertilizer recommendations. High yields can be obtained when 100 to 120 lb/acre of nitrogen are available. A limited amount of nitrogen may be required for yield goals of 1,000 lb/acre, unless a similarly deep-rooted crop such as safflower or sunflower was grown during the previous three to five years. More fertilizer may be necessary if safflower follows a deep-rooted crop in the rotation. Use of a phosphorus fertilizer does not consistently improve seed yield and quality unless applied on soils testing low or very low. Potassium fertilizer (K2O) is applied primarily when very low levels are present. Check the soil test data and fertilizer recommendations for safflower in your area, or consider those from North Dakota (NDSU Extension Circular SF-727, Fertilizing Safflower) if none are available. Common rates include about 20 lb P2O5/acre for soils testing in the medium range or below. Soil pH of 6.0 appear to be adequate. Nitrogen fertilizer can be band applied as anhydrous ammonia, or broadcast as urea or another dry or liquid form, and incorporated shortly after application. Banding or drill application of phosphorus or potassium fertilizer is more effective than broadcast application due to better availability of nutrients. To avoid seedling injury, as with other oilseed crops, do not apply more than 20 lb/acre of nitrogen or potassium fertilizer in drill rows. Urea should not be applied with the drill.
Only varieties that are tolerant to Alternaria leaf spot and bacterial blight are recommended. Descriptions of recent cultivars that were evaluated in North Dakota should be useful to prospective growers (Table 1). Do not mix the seed of linoleic and oleic safflower in planting a crop or at harvest.
- WEED CONTROL
Weeds can be a major problem for safflower crops by reducing potential crop yields. Protection from weed competition during the early portion of the growing season is very important. A dense canopy of vegetation forms as the plants grow, which allows safflower to compete successfully with late-emerging weeds. Safflower with a combination of tillage and herbicides inappropriate for use on cereal grains, can be used to reduce numbers of grassy weeds in a small grain rotation.
Timely and thorough cultivation can provide initial weed-free conditions for the emerging crop. Weeds frequently emerge before safflower and can be controlled in wider rows by a spike-tooth or coil-spring harrow. Harrowing may control some weeds, but damage to the emerging safflower seedlings can occur if the soil is ridged and some plants are buried too deeply.
Dual (metolachlor) and Treflan (trifluralin) are labeled for use on safflower. Dual is applied as either a preplant or preemergence herbicide. Treflan is used as either a fall or spring preplant incorporated treatment. Treflan is primarily used to control grasses, but will control some broadleaf weeds. If there are large numbers of broadleaf weeds, consider not growing safflower in that field. Wild mustard, kochia, and Russian thistle are difficult weeds to control in safflower. The herbicide rate applied will vary with the soil type and organic matter content, and the species of weeds that need to be controlled. Check the label for the correct rate to use on your fields. Table 1. Description of several safflower varieties. S-541, S-208, Hartman, Oker, Girard Finch, Saffire, Centennial, C/W 4440, S-317, MT 3697, Montola 2000
Diseases have caused economic losses in years with above normal rainfall and prolonged periods of high humidity.
Alternaria (Alternaria carthanti) leaf spot and bacterial blight (Pseudomonas syringae) are the most serious disease problems under these conditions. Alternaria leaf spot has symptoms of large, brown irregular spots on leaves and flower bracts. Varieties vary in the degree of resistance they have to leaf spot, and severe losses may occur. Bacterial blight has symptoms similar to those of Alternaria leaf spot that usually appear during periods of heavy rainfall. These leaf lesions have yellow-green margins. Using disease-free seed of a variety with some resistance, and the proper seed treatment before planting, should reduce these disease problems.
Rust (Puccinia carthand) is usually not a problem in safflower since it is easily controlled by seed treatment. There are other diseases that can cause economic losses which have not been a problem in North Dakota during recent years. Flower head rots caused by Sclerotinia and Botrytis, root rots produced by Phytophthora and Pythium fungi, and wilts from Verticillium or Fusarium are included in this list of potential disease problems. A four-year crop rotation should separate safflower from safflower, sunflower, canola, mustard, dry bean, soybean, or lentils so that common disease problems are reduced. Disease problems with safflower have historically been worse in regions east of the Dakotas, where humidity and rainfall are higher.
((Insects and Other Predators))
Safflower can compensate well for insect damage. Economic losses do not usually occur unless the stands are greatly reduced. Growers must consider the effect of any insect control measure on beneficial insects, such as bees, since they are attracted to safflower during the flowering period and improve seed set with their pollination activity. Wireworms, cutworms, and seed corn maggots can be harmful to germinating seeds and seedlings. Seed treatment is an effective control measure. Wireworms can be controlled with Lindane at seeding time or in combination with seed-treatment fungicides. The safflower crop may be damaged later by thrips, lygus bugs, grasshoppers, and sunflower moths. These pests should be controlled only if they reach population levels that can cause serious losses. Severe insect damage that occurs early in the flowering period may cause premature senescence of Rower heads (bronzebeads) with a possible 20 to 30% loss of the crop. Producers should consider the full range of possible cultural and chemical control measures for insect pests. Contact your local county Extension Agent for current control measures.
Safflower is ready to harvest when most of the leaves turn a brown color and very little remains on the bracts of the latest flowering heads green. The stems should be dry, but not brittle, and the seeds should be white and hand threshes easily. This crop should be harvested as soon as it matures in order to avoid the seed discoloration or sprouting in the head that can occur with fall rains. Safflower is an excellent crop for direct combining since it stands well and does not shatter easily. Direct combining may require artificial drying or waiting until green weeds are killed by frosts. The Crop can be windrowed to dry green weeds when moisture content of seed is as high as 25%. The time for harvesting safflower in North Dakota and similar areas of the Upper Midwest can vary from early to late September due to the environmental conditions during the growing season. The combine cylinder speed should be set low at 550 RPM for a 22 in. cylinder to avoid cracking seed. Peripheral speed should be approximately 3,000 ft/minute. Concave clearance should be set at approximately 5/8 in. at the front and 1/2 in. at the back. The reel speed should be about 25% faster than the ground speed. To prevent clogging of the machine from plant residue, the shaker speed must be greater than speeds used for small grains. Air speed should be sufficient to remove most unfilled seeds, straw, and bulls. The combine radiator and air intake should be checked regularly to avoid blockages from the white fuzz of seed heads. Accumulations of this white fuzz can be a fire hazard.
Drying and Storage:
Quality safflower seed should have a white seed coat, a bushel weight over 38 lb, no uncleanable admixtures, and no sprouting, heated seeds. Safflower seed has recently been purchased on a clean basis with a desired oil content of 34 to 36%. Oil content above or below this level results respectively, in a premium or dockage on prices paid to growers. Moisture content of the cleaned seed should not exceed 8% for safe, long-term storage.
Yield Potential and Performance Results:
Seed yields from research trials in North Dakota have varied from less than 500 lb/acre with limited moisture or acute weed and disease problems, to greater than 1,900 lb/acre with adequate moisture and few weed, disease, and insect problems (Table 2). Irrigated fields in California have produced yields with a range of 2,000 to 3,000 lb/acre. Yield trials in western North Dakota and Montana indicated that safflower will produce greater yields than other alternative crops, such as mustard, sunflower, and rapeseed, by 10 to 30%. Evaluations of safflower conducted in Minnesota during the 1950s and 1960s showed yield and oil content to be extremely variable. Seed yields for the best variety in each trial varied from 5 to 1,248 lb/acre with oil contents ranging from 8 to 34%. This great variation in safflower productivity might be due to cool temperatures during the flowering period, which may cause poor seed set and grain filling. These older varieties were also susceptible to diseases enhanced by heavy rainfall and high humidities that can occur in Minnesota.