Canola is a cool-season, annual oilseed crop. It is a member of the mustard family and, in the rosette form in the fall, looks very similar to broccoli or cabbage. In the spring it bolts, reaching a height of 3 to 5 feet, and produces bright yellow flowers. The small, spherical, dark-colored seed, weighing 50 pounds per bushel, contains 40% oil and a residual animal feed meal containing 37-38% protein.
Canola is a type of rapeseed that has been developed to contain less than 2% erucic acid in the oil and less than 30 ppm glucosinolates in the meal. Canola is the coined name selected to identify those rapeseed cultivars which are genetically low in both erucic acid and glucosinolates. In January 1985 the Food and Drug Administration granted GRAS (generally regarded as safe) status, but required that it be labeled as low erucic acid rapeseed (LEAR). In fall 1988 the FDA permitted the use of the name canola or canola oil to be used as the generic name for low erucic acid rapeseed oil. Canola oil is a high quality vegetable oil used as both a cooking oil and a salad oil. The increasing demand for canola oil is caused in part by a health-conscious consumer trying to avoid high levels of cholesterol and saturated fatty acids. Like all vegetable oils, canola oil contains no cholesterol. The level of saturated fatty acids in canola oil is the lowest of all vegetable oils. Therefore, the level of unsaturated fatty acids is the highest of all vegetable oils with a large part consisting of monounsaturated fatty acids.
Canola is best-adapted to well-drained, medium-textured soils with moderate-to-high water-holding capacity. Canola does not tolerate water-logged soil conditions or soils with standing water during the fall and winter months. Entire fields of canola in Indiana have been lost as the result of excessive soil moisture. High clay or wet soils may also result in excessive heaving of the canola plants. Soils that crust easily should also be avoided. The site should be free of problem weeds such as quack grass, canada thistle, and wild mustard. Canola should not be grown on the same site more than once in five years and in most cases will follow wheat or set-aside. Canola may follow corn or soybeans, but the herbicide program for the corn or soybeans needs to be planned with due consideration to the canola crop.
The pH and level of available phosphorus (P) and potassium (K) in the soil should be determined by a soil test. A soil pH of 6.0-6.5 is recommended for canola production. Preplant fertilization should include no more than 30 pounds of available nitrogen (N) per acre. On dark-colored soils or in situations where carryover nitrogen is present, the preplant nitrogen rate should be reduced to zero. Under no circumstances should animal manures or high rates of nitrogen be applied before planting. In a number of cases, excessive fall nitrogen has resulted in increased fall growth, poor hardening of the plant, and significant winter death loss.
The P rates may vary from 20 to 140 pounds per acre (Table 1) and the K rates from 0 to 120 pounds per acre (Table 2) depending on the soil test level and yield goal. Canola is very sensitive to phosphorus and the recommended rates should not be reduced. Generally, the fertilizer is applied broadcast prior to the final disking. In those cases where fertilizer is applied in the furrow, the combined quantity of N and K should not exceed 10 pounds per acre. Even though canola has a high sulfur (S) requirement, lack of S is generally not a problem in Indiana.
Bray P1 Soil P205 rate when bu./a. phosphorus test yield goal is test level level 25-34 35-44 45-54 55+ ____________________________________________________________ lb./a. lb./a. ____________________________________________________________ 0-10 Deficient 90 120 120 140 11-20 Deficient 60 90 90 110 21-30 Deficient 30 60 60 90 31-50 Adequate 20 30 30 60 51-100 Optimum 20 20 20 20 101-300 High 0 0 0 0 >300 Excessive 0 0 0 0 ____________________________________________________________
Phosphorus fertilizer recommendations are made in Indiana based on the Bray P1 phosphorus soil test. Soils should be tested every two to four years. Soils with Bray P1 tests below 15 ppm or 30 pounds per acre are considered deficient and require phosphorus fertilizer for optimum canola production. The recommended rate of P205 given in Table 1 above, should be applied annually at or before planting. Following these recommendations should increase the P soil test level to the adequate range in three to five years.
Soils with Bray P1 tests from 16 to 25 ppm or 31 to 50 pounds per acre are considered adequate for canola production. The recommended rate of P205 given in Table 1 should be applied annually or combined with the recommended rates for rotational crops and applied every two or three years prior to canola seeding. Following these recommendations would result in little change in the soil test levels over time.
Bray P1 soil tests from 26 to 50 ppm or 51 to 100 pounds per acre are considered high. At this range of soil test levels the soil contains adequate residual P to meet the needs of 4 to 12 successive cropping seasons depending on the crop grown. However, due to the high P response found with winter canola, a small amount of P should be applied at seeding to encourage root development and improve winter hardiness. Farmers who wish to maintain soil tests at this level can do so by applying P205 at rates equivalent to those recommended for the same yield potential at adequate soil test levels.
Bray P1 soil tests form 51 to 150 ppm or 101 to 300 pounds per acre are considered very high. No P fertilizer is needed for canola production at this soil test level. There are no agronomic reasons to apply fertilizer to maintain soil tests at these levels.
Bray P1 soil tests above 150 ppm or 300 pounds per acre are considered excessive. While few adverse effects of these high levels to canola are known, the potential for adding P to ground and surface waters increases at these levels. No P fertilizers are needed for canola production. Soils with these P soil test levels would not be recommended as sites for the disposal of P-containing manures or sludges.
Exchange Soil K2O rate when bu./a. potassium test yield goal is test level level 25-34 35-44 45-54 55+ ______________________________________________________________ lb./a. lb./a. 0-80 Deficient 90 120 120 120 81-150 Deficient 60 90 90 90 151-210 Deficient 30 60 60 60 211-300 Adequate 20 30 30 30 301-400 Optimum 0 0 0 0 401-600 High 0 0 0 0 >600 Excessive 0 0 0 0 ______________________________________________________________
Potassium fertilizer recommendations are made in Indiana based on the exchangeable K soil test. For best results, soils should be tested every two to four years.
Soils with exchangeable K soil tests below 150 ppm or 210 pounds per acre are considered deficient and require potassium fertilizer for optimum canola production. The recommended rate of K2O given in Table 2 should be applied annually at or before planting. Following these recommendations should increase the K soil test to the adequate range in three to five years.
Soils with exchangeable K soil tests for 106 to 150 ppm or 211 to 300 pounds per acre are considered adequate for canola production. The recommended rate of K2O given in Table 2 should be applied annually or combined with the recommended rates for rotational crops and applied every two or three years prior to canola seeding. Following these recommendations should result in little change in soil test levels over time.
Exchangeable K soil tests from 150 to 200 ppm or 301 to 400 pounds per acre are considered high. At this range of soil test levels the soil contains adequate residual K to meet the needs of 4 to 12 successive cropping seasons depending on the crop grown. Farmers who wish to maintain soil tests at this level can do so by applying K2O at rates equivalent to those recommended for the same yield potential at adequate soil test levels.
Exchangeable K soil tests from 201 to 300 ppm or 401 to 600 pounds per acre are considered very high. No K fertilizer is needed for canola production at this soil test level. There are no agronomic reasons to apply fertilizer to maintain soil tests at these levels.
Exchangeable K soil tests above 300 ppm or 600 pounds per acre are considered excessive. While few adverse effects of these high levels to canola are known, the potential for adding K to ground and surface waters increases at these levels. No K fertilizers are needed for canola production. Soils with these K soil test levels would not be recommended as sites for the disposal of K-containing manures or sludges.
Currently there are a number of good varieties of winter canola available for planting in Indiana. Plant only canola quality varieties having oil with less than 2 percent erucic acid and meal with less than 30 parts per million of glucosinolates. Other characteristics of importance when selecting a canola variety include: winter-hardiness, yield-potential, lodging-resistance, disease-resistance, and acceptable seed quality. It is extremely important to use only certified seed since it assures the producer of true canola quality and freedom from contamination with mustards, high erucic acid rapeseed, and weed seeds. The seed tag should also state the variety name and the percent germinable seed. Until more is learned regarding seed-borne diseases, canola seed should be treated with a fungicide. It is never advisable for a producer to save and plant seed from year-to-year, since there is no assurance of purity, seed quality, or that canola quality is maintained.
Proper seedbed preparation is essential to establish a solid, uniform stand of canola. Since the seed is quite small, a clean and level seedbed that is granular, but firm, with good moisture is necessary to provide good seed-to-soil contact and rapid emergence. When canola is to follow wheat, the wheat stubble should be plowed within two to three weeks after wheat harvest. This will allow adequate time for the soil to firm and for the wheat seed to sprout to minimize volunteer wheat plants in the canola. The field should be disked lightly and firmed with a cultipacker or roller just prior to planting.
Canola requires at least 45 days of growth, after emergence in the fall, to develop adequate winter-hardiness. During this period, the plants need a minimum of 6 to 8 fully developed leaves before a killing frost occurs. The optimum planting dates in Indiana range from August 15 in the north to September 15 in the south. Planting later than the suggested dates can result in decreased winter survival, as well as reduced yields. Planting earlier than the suggested date can also result in decreased winter survival, particularly if bud formation and stem elongation occur in the fall prior to onset of winter dormancy. The proper planting date is the second most important factor to consider after site selection.
The proper seeding rate depends upon the seeding method. When canola is planted with a grain drill, a seeding rate of 10-12 seeds per square foot, approximately 4-5 pounds per acre, should result in a final stand of 6-8 plants per square foot. A grass or alfalfa seed attachment on the drill gives the most precise seeding rate and placement. However, most grain drills can be adjusted to seed at 10-12 seeds per square foot through the grain box. The seed needs to be checked inside the grain box to make sure it is not being ground or damaged by the fluted feed mechanism. A 3/8- to 1/2-inch planting depth, with very little downward pressure on the seed openers and light pressure on the press wheels, is recommended.
Canola can also be broadcast-seeded. After a firm seedbed is prepared, the seed is broadcast at 6 to 8 pounds per acre, and a cultipacker is used to press the seed into the soil. A cultipacker seeder may also be used, but good soil moisture at the surface is required for stand establishment. Plant populations of 6 to 8 plants per square foot are considered ideal for top yields.
Canola responds to nitrogen fertilizer applied in late winter while the plants are still dormant. The total nitrogen requirement for 45 bushels-per-acre yield is approximately 135 pounds of available nitrogen per acre. Of this 135 lb./a., 110 to 120 pounds should be supplied by nitrogen fertilizer and the balance from residual nitrogen in the soil. Topdressing in mid-February to early March, as the plant breaks dormancy, with 30 to 120 pounds N per acre (Table 3) complements the preplant-applied nitrogen to maximize the economic yield.
Cation Nitrogen rate when exchange bu./a. yield goal is capacity 25-34 35-44 45-54 55+ ______________________________________________ meq/100g. lb./a. ______________________________________________ <6 60 70 90 120 7-10 50 60 80 110 11-30 40 50 70 100 >30 30 40 60 90 ______________________________________________ * Assumes 30 lb./a. N was applied at seeding.
Very little is known regarding weed problems with canola production in Indiana. A first step in minimizing weed competition is to plant the crop in a clean seedbed. The second key to good weed control is the establishment of a good stand of 6 to 8 plants per square foot in the fall. The vigorous early growth habit of canola permits the crop to compete well with most common weeds in the fall and early spring, without the use of herbicides. A possible exception is when canola is planted following a small grain crop and the volunteer grain becomes a problem. Trifluralin, preplant incorporated, is the only herbicide registered for grass control in canola. However, research from some other states indicates that yield reduction can occur when trifluralin is used and the canola plants become stressed in the fall. There are no herbicides registered for broadleaf weed control in canola. Avoid fields with a history of wild mustard because of a potential cross-pollination problem, as well as direct competition. Canada thistle- or quack grass-infested fields should also be avoided. Since canola is a broadleafed plant, it is sensitive to residual herbicides used for control of broadleaf weeds in the preceding crop.
A good stand of canola is also competitive in the late winter and early spring and normally outgrows spring-emerging weeds. It breaks dormancy in March, before many weeds germinate, and provides complete ground cover to prevent weed growth in spring.
Since canola is relatively new to Indiana, little is known about insect and disease problems. As a member of the mustard family, canola could be attacked by the diseases and insects that attack other domesticated and wild members of this family of plants. Presently, very few pesticides are registered in the United States for use on canola. Therefore, it is very important to follow a crop rotation which includes canola no more than once in five years.
Diseases most likely to damage canola in Indiana are the damping off or seedling blight fungi (Pythium, Rhizoctonia, Fusarium spp.) and Sclerotinia stem rot. The Rhizoctonia, Fusarium. and Pythium fungi are present throughout Indiana and may cause stand establishment problems in wet soils. Captan is registered in Indiana as a seed treatment on canola and may help control these seedling diseases. Additionally, when conditions are favorable, Rhizoctonia crown rot can be a problem in late winter or early spring.
Sclerotinia stem rot is a serious disease which can occur in the spring during wet weather and warm temperatures and is most often observed after flowering begins. The white mold girdles the stem, resulting in premature bleaching of the plants and resultant low seed yields. Infected plants are highly visible among the remaining healthy green plants in the field. The hard, black sclerotia (resting bodies of the fungus) may be found inside the affected stems, branches, or pods. The sclerotia can remain viable for up to 7 years when buried in the soil. Crop rotation and cultural practices are the primary methods of Sclerotinia control. Canola should not be planted in a rotation within five years of a susceptible crop which has had symptoms of Sclerotinia stem rot, and should not follow itself in the same field for a four-year period. Crops susceptible to Sclerotinia in Indiana include soybeans, red clover, sunflower, and alfalfa. Wild members of the mustard family are also susceptible. Cereals and grasses are immune to the disease and can precede canola in the rotation.
Blackleg (Leptosphaeria maculans) is a very serious disease of crops of the mustard family and can be devastating in canola. The disease has not been positively identified in Indiana. Blackleg can be easily spread on the seed of canola. To avoid the introduction or spread of the disease, only certified seed should be used and fungicide seed treatment is suggested. Pseudocercosporella capsillae and Alternaria Brassicae are two foliar diseases to which canola is susceptible. So far, these two diseases have not been observed in Indiana at levels to cause an economic crop loss.
Insects known to attack canola include aphids, cabbage seedpod weevil, flea beetles, lygus bugs, cutworms, and other caterpillars. All of these insects have been observed in canola fields in Indiana; however, none of them has reached populations approaching the economic threshold. Crop rotation and control of volunteer canola and wild members of the mustard family are good precautions to help control insects and diseases that can attack canola.
Canola grows to a height of 3 to 5 feet and is direct-combined with a grain head. The small, spherical seed is contained in pod-like structures that are 3 to 5 inches long. Seed maturity begins at the base of the plant and progresses toward the top. This may result in uneven maturity which could cause shattering of some of the lower pods before desired harvest maturity is attained. Harvest must wait until there are a minimum of green seeds in the pods and seed moisture drops below 10%. If the moisture meter does not have a canola chart, use the rapeseed chart or contact the manufacturer of the meter for a canola/rapeseed chart or a conversion chart. Since seed moisture decreases rapidly at maturity, fields should be monitored daily to prevent excessive shattering due to delayed harvest. The crop should be cut about 12 to 24 inches above the soil surface, just below the lowest seed pods. Cutting the canola stalk a great deal lower can result in excessive green stalk material in the seed.
Before harvesting, the combine should be thoroughly checked for holes or potential points where the seeds might leak from the combine. Points that should be checked include the table, grain tank, feeder housing, and the lower inspection or clean-out doors on the elevators. When holes are found, they should be covered with duct tape. Most combine manuals include instructions on recommended settings for harvesting rapeseed. These should be the first settings for the combine. If header losses occur, check to make certain the reel speed is equal to the ground speed of the combine. The cross auger should be set just low enough to provide an even flow of material from the table. If the clearance is too close, pods will be threshed on the table, causing excessive seed loss. Cylinder speeds should be initially set in the range of 400 to 750 rpm, with the concave clearance from 5/8-to 3/4-inch in front and 1/4-to 3/8-inch at the rear. The fan speed should be set at about 3/ 4 of that used for wheat.
With the combine properly adjusted, make a pass across the field with the combine running at capacity. Just before reaching the end of the field, stop the combine and check for seed loss from the header, leaks in various components of the combine, and seed being blown out the back of the combine. The crop residue behind the combine should also be checked for broken or crushed seed. Check the tank for cleanliness of the seed. If seed loss is occurring, recheck the items above and adjust accordingly. If broken seeds are found, or if there is excessive foreign material in the tank, the concave clearance should be opened wider and/or the cylinder speed reduced. The combine should also be checked for the amount of material being returned. If the returns are too high, the air flow may be too low, the top sieve may be too widely opened, or the cylinder and/or concave is over-threshing.
Seed moisture content of less than 8% is required for safe storage of canola. It will be essential to have some air flow through the seed shortly after binning to achieve uniform moisture throughout the bin. Most of the canola grown in the Midwest has been delivered directly to the collection point for marketing the crop.
In recent harvests, seed was sold to one of a number of elevators in the state. In most cases, the seed was shipped directly to the processor in Hamilton or Windsor, Ontario, Canada. Typically a train carload of canola from several growers is collected before it is shipped for processing. Prices received for canola are based on the Winnipeg, Manitoba market, less shipping costs, grain elevator handling fees, and conversion rates of the Canadian dollar to U.S. dollar. Since canola is 40% oil, its price will depend to a great extent on the market price for vegetable oils. Therefore, price will tend to rise and fall with the soybean oil market and the cash market of soybeans at the time of sale.
The final price of canola, paid to the producer, is dependent on more than the Winnipeg rapeseed futures market and the price of soybeans. The local quoted price is subject to discounts for damaged seed, foreign material, garlic, green seed, and moisture.
Canola production inputs are essentially the same as for wheat. This is because the same equipment is used to produce the two crops and labor requirements are similar. With the exception of N, where canola has a higher requirement, all other costs will be similar. Thus, a wheat yield of 60 bushels per acre (@$3.50/bu.) and a canola yield of 45 bushels per acre (@$5.00/bu.) will give the same net return per acre.
Cooperative Extension work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agriculture cooperating: H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the acts of May 8 and June 30, 1914. The Cooperative Extension Service of Purdue University is an equal opportunity/equal access institution.