¹Department of Agronomy and Soil Science, College of Agricultural and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706.
²Departments of Agronomy and Plant Genetics, and Entomology, University of Minnesota, St. Paul, MN 55108.
³Center for Alternative Plant and Animal Products, University of Minnesota, St. Paul, MN 55108.
July, 1991.

I. History:

Crambe (Crambe abyssinica Hochst.) is believed to be a native of the Mediterranean area. The oilseed crop contains an inedible oil used for industrial products. It has been grown in tropical and subtropical Africa, the Near East, Central and West Asia, Europe, United States, and South America. It was first used as a crop in 1933 at the Boronez Botanical Station, U.S.S.R., and has been a part of a Swedish breeding program since 1949.

Crambe was introduced to the U.S.A. by the Connecticut Agricultural Experiment Station in the 1940s. Evaluations for strains of the crop began in Texas in 1958. Crambe has since been successfully grown in several areas of the United States.

II. Uses:

The oil extracted from crambe seed is used as an industrial lubricant, a corrosion inhibitor, and as an ingredient in the manufacture of synthetic rubber. The oil contains 50 to 60% erucic acid, a long chain fatty acid, which is used in the manufacture of plastic films, plasticizers, nylon, adhesives, and electrical insulation.

Crambe is being promoted as a new domestic source of erucic acid, which has primarily come from imported rapeseed oil. Supplies of industrial rapeseed are less-plentiful since the development of varieties (Canola) that have no erucic acid content. The United States uses up to 40 million pounds of high-erucic acid oil annually mostly imported from Poland and Canada. Although rapeseed is grown domestically, crambe oil contains 8 to 9% more erucic acid than industrial rapeseed oil, and the crop is better suited to the higher rainfall areas of the U.S.

Defatted crambe seed meal can be used as a protein supplement in livestock feeds. The meal contains 25 to 35% protein when the pod is included and 46 to 58% protein when the pod is removed. It has a well balanced amino acid content and has been approved by the FDA for use in beef cattle rations for up to 5% of the daily intake.

The meal has not been approved for nonruminant rations because it may contain glucosinolates, which may be broken down in digestive systems to form harmful products that can cause liver and kidney damage, and appetite depression. Untreated, oil-free crambe meal may contain up to 10% thioglucosides, which are toxic to nonruminant animals, such as hogs and chickens. However, subjecting whole seed to moist heat before processing can deactivate the enzyme, and the glucosinolates remain intact through the oil extraction process.

III. Growth Habits:

Crambe, which is closely related to rapeseed and mustard, is an erect annual herb with numerous branches that grows to a height of 24 to 40 in. Under stress conditions plants may develop long tap roots, which later become conical. The leaves are oval shaped, but asymmetric. The leaf blade is approximately 4 in. long and 3 in. wide, with a smooth surface; the petiole is channeled, about 8 in. long, and pubescent (hairy).

Crambe initially produces numerous small, white flowers in a compact group, which are later distributed on 1 to 2 ft stalks or spikes. The spherical fruits bear one seed each. The seed remains in the pod or hull at harvest. Mature fruits are dry, persistent and indehiscent. They vary in color from light green to light brown. Crambe seeds weigh approximately 0.25 oz/1,000 seeds and have a hull content of 25 to 30%.

IV. Environmental Requirements:

A. Climate:

Crambe is widely adapted and can be grown as a spring crop in the Midwest, Pacific Northwest, and Southwest of the U.S.A. This oilseed crop is a cool season one and can tolerate temperatures as low as 24^oF. The crop requires 90 to 100 days from planting to maturity. Although it is relatively drought-tolerant, the best yields have been obtained in moist areas. While crambe requires adequate soil moisture during pod set and filling, a subsequent dry period as the plant matures promotes high yields.

B. Soil:

Well-drained, fertile soils of moderately coarse to fine texture with a pH of 6.0 to 7.0 or slightly higher, are best suited for crambe production. The crop will not tolerate heavy clay, wet or waterlogged soils.

C. Seed Preparation and Germination:

For highest yields, certified seed should be used that is free of viruses. Seed can be treated with a fungicide or soaked in water at 140^oF for 20 minutes or at 130^oF for 30 minutes to reduce problems with Alternaria brassicicola.

V. Cultural Practices:

Machinery used for tillage, planting, spraying, and harvesting crambe is similar to that used for small grains. Farmers producing small grains would not have to purchase additional machinery to produce crambe.

A. Seedbed Preparation:

The soil should be plowed or disked and then worked with a cultipacker and heavy drag. Smoothing and packing are usually essential to provide a smooth, firm seedbed and to ensure seed placement at a uniform depth. Soybean-stubble fields have been disked and smoothed for planting with satisfactory results. When growing crambe following wheat or barley, the straw should be removed or a chopper used on the combine at harvest. A seedbed can then be prepared by disking the wheat stubble. This method will help conserve soil moisture after wheat.

B. Seeding date:

Crambe can be planted as soon as the threat of temperatures below 24^oF has passed -- mid to late April in Wisconsin and Southern Minnesota and late April to early May in northern areas of these states.

C. Method and Rate of Seeding:

Crambe can be solid-seeded or planted in rows, depending on the equipment available. For solid seeding, a small grain drill or cultipacker seeder may be used. Since solid-seeded crambe cannot be cultivated, it should be grown in fields where weeds are not a problem.

When crambe is planted in 20 to 30 in. rows, a corn planter fitted with corn or soybean plates can be used. Planting in rows will result in more uniform emergence, less loss due to soil crusting, and lower seed cost. In addition, narrow rows promote reduced branching and more uniform maturity. Acceptable yields have been recorded for row widths ranging from 6 to 36 in. However, where weeds are not a serious problem, row widths of 6 to 12 in. give highest yields. Crambe planted in rows wider than 30 in. will tend to lodge, making harvest difficult.

Planting depth is a critical factor in obtaining good crambe yields. Seed should be planted 3 in. deep in humid regions and up to 1 in. deep in drier areas. A cultipacker seeder does an excellent job of placing the seed at the appropriate depth. A seeding rate of 10 to 20 lb/acre is recommended.

D. Fertility and Lime Requirements:

Phosphorus and potassium recommendations for small grains are usually adequate for crambe also. For soils showing an option test in phosphorus and potassium, approximately 45 lb/acre of P₂O₅ and 80 lb/acre of K₂O are recommended. Crambe also responds to nitrogen fertilizer with approximately 80 to 100 lb/acre of actual N recommended. Credits for legume or manure N should be taken when appropriate. Like rapeseed, crambe may respond to sulfur (20 to 25 lb/acre) on low sulfur soils.

E. Variety Selection:

The number of crambe varieties available for commercial production is limited. Meyer is the only variety available in sufficient quantity for field production. Belann, Belenzian, Indy, and Prophet are other registered varieties; however, commercial seed supplies of these varieties do not exist. Three varieties of crambe were tested at four locations in North Dakota in 1990 (Table 1). Seed yields, as well as other agronomic characters for crambe were evaluated in Minnesota during 1960 to 1974 (Table 2).

Table 1. Relative yield performance of crambe varieties at Carrington, North Dakota, 1988-90.
Variety	1990	1988-1990
	------------------------- lb/acre ------------------
Belann	2175.3	1487.3
Belenzian	2008.0	1429.6
Meyer	1726.2	1353.5
Source: Crop Production Guide 1991. North Dakota State University Extension Service, Fargo, ND 58105.

Table 2. Summary of crambe performance data from Rosemount, MN, 1960-1974¹ .
Variety	Year(s)	Maturity Date	Height	Lodging²	Seed Weight	Bushel Weight	Oil Content	Yield
			(in.)		(g/1000 seeds)	(lb./bu)	%	(lb/acre)
Unknown	1960-62	8-8	46	5.1	5.9	24.0	35.3	1,499
MN24427	1963	8-2	44	4.7	5.8	23.6	28.7	950
Indy	1967	7-27	39	2.0	6.4	25.5	27.8	1,334
MN24427	1967	8-7	41	5.7	7.9	23.3	32.0	1,214
Crookston 65	1973	7-28	37	3.0	6.7	2l.0	31.5	1,632
Prophet	1973	7-25	38	2.4	7.0	22.4	32.0	1,960
Indy	1973	7-20	33	1.7	5.7	24.1	29.7	936
Meyer	1973	7-20	34	3.0	7.0	22.7	30.8	1,825
Meyer	1974	7-25	41	1.3	--	23.8	30.8	1,446
¹Source: R. G. Robinson and D. H. Putnam, Dept. of Agronomy and Plant Genetics, University of Minnesota, St. Paul, MN. ²1 = erect, 9 = flat.

F. Weed Control:

Weed competition can reduce crambe yields significantly. Some of the weeds that may cause difficulties are pigweed, foxtail, smartweed, lambsquarter, ragweed, and kochia.

A uniform, thick stand of crambe is an effective means of weed control. Early planting also increases crambe's ability to compete with weeds, which require a higher soil temperature for germination. However, as crambe approaches maturity, weeds may emerge through the crop canopy, posing problems with harvest and increasing the moisture of harvested crambe seed. Crambe planted in 20 to 30 in. rows can be cultivated to control weeds.

No herbicides have been registered for use on crambe in the U.S. Crambe is very susceptible to injury from 2,4-D drift and the residual effects of atrazine.

G. Diseases and Their Control:

The most serious disease in crambe is caused by Alternaria brassicicola. This fungus causes darkening of the seed and stems, and reduces seed germination. Crambe is also susceptible to turnip mosaic virus. Use of high-quality seed is the best defense against disease problems. The seed can also be treated with a fungicide or hot water (as described in the section on seed preparation) prior to planting.

H. Insects and Other Predators and Their Control:

Crambe seedlings may be attacked by flea beetles and aphids. At the present time there are no insecticides labeled for insect control. If insecticides were available, insect control should be avoided during bloom because of the beneficial value of pollinators.

I. Harvesting:

As crambe approaches maturity, the leaves turn yellow and drop from the plant. A few days after the last leaves have fallen, the seed pods and small branches turn a straw color. When this color has progressed down the stems below the last seed-bearing branches -- generally 90 to 100 days after planting -- the seed should be ready to harvest. Crambe is susceptible to seed shatter and a higher risk of Alternaria brassicicola infection if harvest is delayed until all the seeds change color.

Crambe can be harvested with a standard combine with adjustable sieves. If the plants are standing, they should be cut 12 to 18 in. above the soil surface. The seed should be harvested with the hulls intact. A cylinder speed of 400 to 500 RPM and concave clearance of 3/8 in. are recommended. The air should be set as low as possible with fan speed at less than 500 RPM, but never disconnect the fan to completely shut off the air flow. Set the reel to move only slightly faster than the ground speed of the combine to minimize shattering. Crambe seed is small, round, and very lightweight. To prevent losses, a transport vehicle with no cracks or holes should be used, and the load should be completely covered with a tarp.

J. Drying and Storage:

Crambe should be dried to no more than 10% moisture before storage. Before storing the seed, it should be passed over a scalper to remove trash.

Store crambe in clean, insect-free bins with perforated floors and a fan. A corn storage bin is suitable for crambe.

Even if the crambe seed is dry at harvest, it may contain green plant parts from weeds and grass, as well as insect parts. This wet trash can cause the seed to heat in a short time. To prevent heating, aerate the seed as soon as the bin floor is covered with 2 to 3 ft of seed. Use a minimum air flow of 0.1 cfm per bushel. Continue aeration until the moisture and temperature of the seed have reached equilibrium throughout the bin.

The fan may also be used to continue drying the seed in the bin. Bin-drying with unheated air requires a minimum air flow of 1 cfm per bushel and should not be attempted if the moisture level in the seed exceeds 20%. Seed depth in the bin should be limited to 16 ft. Heat-sensing equipment can help detect hot spots within the grain mass.

VI. Yield Potential and Performance Results:

Crambe has yielded up to 2,500 lb/acre on small commercial fields and demonstration plots. A yield of 1,200 to 1,800 lb/acre is more typical in commercial production fields with good management practices.

VII. Economics of Production and Markets:

Production costs for crambe in the Midwest are approximately the same as those for wheat, except for the higher cost of crambe seed, since the same equipment and methods are used. In 1990, crambe yielding 1,500 lb/acre in the Midwest cost almost $0.10/lb to produce. Crambe production would not compete directly with domestic seed oils since it would provide a substitute for erucic acid extracted from imported rapeseed.

There is no broad commercial outlet for crambe seed, and growers are advised to identify a market before planting. Crambe seed meal has little market value, but can be useful in livestock feed. Finding additional uses for crambe meal will enhance the value of the seed.

VIII. Information Sources:

* Crambe -- A Potential New Crop for Indiana. Christmas, E.P., K.J. Lessman, C.B. Southard, and M.W. Phillips. Cooperative Extension Service, Purdue University, Lafayette, IN. Bulletin AY-168.

* Crambe Production. 1988. Iowa State University Extension, Ames, IA 50011. Bulletin Pm-1333.

* Crambe Production. Endres, G. and B. Schatz. 1991. North Dakota State University Extension Service, Fargo, ND. Extension Folder A-1010.

* Crop Production Guide 1991. North Dakota State University Extension Service, Fargo, ND 58105.

* Crambe. Papathanasiou, G.A., and K.J. Lessman. 1966. Purdue University Agricultural Experiment Station, Lafayette, IN. Research Bulletin 819.

* Industrial Feedstocks and Products from High Erucic Acid Oil: Crambe and Industrial Rapeseed. Van Dyne, D.L., M.G. Blase, and K.D. Carlson. 1990. University of Missouri-Columbia.

* An Introduction to Crambe. Woolley, D.G. 1988. Iowa State University, Ames, IA 50011.

* Alternative Crop and Alternative Crop Production Research - A Progress Report, February 1991. J. C. Gardner (ed.), North Dakota State University.

The information given in this publication is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no endorsement for one product over other similar products is implied by the Minnesota and Wisconsin Extension Services.