D. H. Putnam1, E. S. Oplinger2, D. R. Hicks1, B.
R. Durgan1, D. M. Noetzel1, R. A. Meronuck1, J.
D. Doll2, and E. E. Schulte2
1Departments of Agronomy and Plant Genetics, Entomology and Plant Pathology.
University of Minnesota, St. Paul, MN 55108.
2Departments of Agronomy and Soil Science, College of Agricultural and
Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison,
Sunflower (Helianthus annuus L.) is one of the few crop species that originated
in North America (most originated in the fertile crescent, Asia or South or Central
America). It was probably a "camp follower" of several of the western native American
tribes who domesticated the crop (possibly 1000 B.C.) and then carried it eastward
and southward of North America. The first Europeans observed sunflower cultivated
in many places from southern Canada to Mexico.
Sunflower was probably first introduced to Europe through Spain, and spread through
Europe as a curiosity until it reached Russia where it was readily adapted. Selection
for high oil in Russia began in 1860 and was largely responsible for increasing
oil content from 28% to almost 50%. The high-oil lines from Russia were reintroduced
into the U.S. after World War II, which rekindled interest in the crop. However,
it was the discovery of the male-sterile and restorer gene system that made hybrids
feasible and increased commercial interest in the crop. Production of sunflowers
subsequently rose dramatically in the Great Plains states as marketers found new
niches for the seeds as an oil crop, a birdseed crop, and as a human snack food.
Production in these regions in the 1980s has declined mostly because of low prices,
but also due to disease, insect and bird problems. Sunflower acreage is now moving
westward into dryer regions; however, 85% of the North American sunflower seed is
still produced in North and South Dakota and Minnesota.
A. Edible oil:
Commercially available sunflower varieties contain from 39 to 49% oil in the seed.
In 1985-86, sunflower seed was the third largest source of vegetable oil worldwide,
following soybean and palm. The growth of sunflower as an oilseed crop has rivaled
that of soybean, with both increasing production over 6-fold since the 1930s. Sunflower
accounts for about 14% of the world production of seed oils (6.9 million metric
tons in 1985-86) and about 7% of the oilcake and meal produced from oilseeds. Europe
and the USSR produce over 60% of the world's sunflowers.
The oil accounts for 80% of the value of the sunflower crop, as contrasted with
soybean which derives most of its value from the meal. Sunflower oil is generally
considered a premium oil because of its light color, high level of unsaturated fatty
acids and lack of linolenic acid, bland flavor and high smoke points. The primary
fatty acids in the oil are oleic and linoleic (typically 90% unsaturated fatty acids),
with the remainder consisting of palmitic and stearic saturated fatty acids. The
primary use is as a salad and cooking oil or in margarine. In the USA, sunflower
oils account for 8% or less of these markets, but in many sunflower-producing countries,
sunflower is the preferred and the most commonly used oil.
High oleic sunflower oil (over 80% oleic acid) was developed commercially in 1985
and has higher oxidated stability than conventional oil. It has expanded the application
of sunflower oils for frying purposes, tends to enhance shelf life of snacks, and
could be used as an ingredient of infant formulas requiring stability.
Non-dehulled or partly dehulled sunflower meal has been substituted successfully
for soybean meal in iso-nitrogenous (equal protein) diets for ruminant animals,
as well as for swine and poultry feeding. Sunflower meal is higher in fiber, has
a lower energy value and is lower in lysine but higher in methionine than soybean
meal. Protein percentage of sunflower meal ranges from 28% for non-dehulled seeds
to 42% for completely dehulled seeds. The color of the meal ranges from grey to
black, depending upon extraction processes and degree of dehulling.
C. Industrial Applications:
The price of sunflower oil usually prohibits its widespread use in industry, but
there are several applications that have been explored. It has been used in certain
paints, varnishes and plastics because of good semi-drying properties without color
modification associated with oils high in linolenic acid. In Eastern Europe and
the USSR where sunflower oil is plentiful, sunflower oil is used commonly in the
manufacture of soaps and detergents. The use of sunflower oil (and other vegetable
oils) as a pesticide carrier, and in the production of agrichemicals, surfactants,
adhesives, plastics, fabric softeners, lubricants and coatings has been explored.
The utility of these applications is usually contingent upon petrochemical feedstock
Sunflower oil contains 93% of the energy of US Number 2 diesel fuel (octane rating
of 37), and considerable work has been done to explore the potential of sunflower
as an alternate fuel source in diesel engines. Blends of sunflower oil and diesel
fuel are expected to have greater potential than the burning of pure vegetable oil.
The use of sunflower seed for birdfeed or in human diets as a snack, has grown consistently
over the past 15 years. Varieties used for non-oilseed purposes are characterized
by a larger seed size and require slightly different management practices. During
processing, seed is divided into 1) larger seed for in-shell roasting, 2) medium
for dehulling, and 3) small for birdseed. Standards for different uses vary.
Sunflower can also be used as a silage crop. It can be used as a double crop after
early harvested small grains or vegetables, an emergency crop, or in areas with
a season too short to produce mature corn for silage.
Forage yields of sunflower are generally less than corn when a full growing season
is available. In one study, sunflower dry matter yields ranged from 2.0 to 3.0 ton/acre
compared with 3.1 to 3.8 ton/acre for corn. Moisture content of sunflower at maturity
is usually high (80 to 90%) and would require wilting before ensiling.
Nutritional quality of sunflower silage is often higher than corn but lower than
alfalfa hay (Table 1). Crude protein level of sunflower silage is similar to grass
hay and higher than corn silage. Generally, crude protein of sunflower decreases
and lignin percentage increases after the flowering stage. High plant populations
increases fiber and lignin percentage. Seed size does not seem to affect yield or
Sunflower silage contains considerably more fat than many other forages, (Table
1). Some producers and researchers in Oregon have experimented with sunflower/corn
intercrops to increase energy content of a silage, but results of this work are
not yet complete. In South Dakota trials, milk yields were reduced by 9% when straight
sunflower silage was compared with corn. The nutritional quality of sunflower silage
is generally recognized as adequate for dry cows, steers, and low milk producers.
Table 1: Nutritional quality of sunflower, immature corn, and mature corn silage,
alfalfa hay (harvested in early bloom) and timothy hay (harvested in late Vegetative
--------------- % of Dry Matter ---------------
Total Digestible Nutrients
Acid Detergent Fiber
1Data from Miller, Oplinger and Collins, 1986.
2In vitro dry matter
III. Growth Habit:
Sunflower is an annual, erect, broadleaf plant with a strong taproot and prolific
lateral spread of surface roots. Stems are usually round early in the season, angular
and woody later in the season, and normally unbranched.
Sunflower leaves are phototropic and will follow the sun's rays with a lag of 12o
behind the sun's azimuth. This property has been shown to increase light interception
and possibly photosynthesis.
The sunflower head is not a single flower (as the name implies) but is made up of
1,000 to 2,000 individual flowers joined at a common receptacle. The flowers around
the circumference are ligulate ray flowers without stamens or pistils; the remaining
flowers are perfect flowers (with stamens and pistils). Anthesis (pollen shedding)
begins at the periphery and proceeds to the center of the head. Since many sunflower
varieties have a degree of self-incompatibility, pollen movement between plants
by insects is important, and bee colonies have generally increased yields.
In temperate regions, sunflower requires approximately 11 days from planting to
emergence, 33 days from emergence to head visible, 27 days from head visible to
first anther, 8 days from first to last anther, and 30 days from last anther to
maturity. Cultivar differences in maturity are usually associated with changes in
vegetative period before the head is visible.
IV. Environmental requirements:
Sunflower is grown in many semi-arid regions of the world from Argentina to Canada
and from central Africa into the Soviet Union. It is tolerant of both low and high
temperatures but more tolerant to low temperatures. Sunflower seeds will germinate
at 39o F, but temperatures of at least 46 to 50o F are required
for satisfactory germination. Seeds are not affected by vernalization (cold) in
the early germination stages. Seedlings in the cotyledon stage have survived temperatures
down to 23o F. At later stages freezing temperatures may injure the crop.
Temperatures less than 28o F are required to kill maturing sunflower
Optimum temperatures for growth are 70 to 78o F, but a wider range of
temperatures (64 to 91oF) show little effect on productivity. Extremely
high temperatures have been shown to lower oil percentage, seed fill and germination.
Sunflower is often classified as insensitive to daylength, and photoperiod seems
to be unimportant in choosing a planting date or production area in the temperate
regions of North America. Oil from northern regions tends to be higher in linoleic
acid and has a higher ratio of polyunsaturated to saturated fatty acids than oil
produced in southern latitudes.
Sunflower is an inefficient user of water, as measured by the amount of water transpired
per gram of plant above-ground dry matter. Levels were 577 (g H2O/g DM)
for sunflower, 349 for corn, 304 for sorghum in an Akron, Colorado study. It is
similar to wheat, soybean, fieldbean, oat, and rape in that respect. Efficiency
is measured at an optimum moisture level and is not a measure of drought resistance.
Sunflower is not considered highly drought tolerant, but often produces satisfactory
results when other crops are damaged during drought. Its extensively branched taproot,
penetrating to 6.5 ft, aids the plant during water stress. A critical time for water
stress is the period 20 days before and 20 days after flowering. If stress is likely
during this period, irrigation will increase yield, oil percentage and test weight,
but decrease protein percentage.
Sunflower will grow in a wide range of soil types from sands to clays. The demands
of a sunflower crop on soil macronutrients are not as great as corn, wheat or potato.
As with other non-leguminous grain crops, nitrogen is usually the first limiting
factor for yield. Medium to high levels of macronutrients are usually required for
good plant growth. Sunflower stover contains a large proportion of these elements,
which means sunflower is relatively inefficient in the use of these elements. However,
most of these nutrients are returned to the soil with the stover.
Sunflower is low in salt tolerance but is somewhat better than fieldbean or soybean
in this respect. Corn, wheat, rye and sorghum are rated medium, and sugarbeet and
barley are high in salt tolerance.
Good soil drainage is required for sunflower production, but this crop does not
differ substantially from other field crops in flooding tolerance.
V. Cultural Practices:
A. Seedbed Preparation:
Many different tillage systems can be used effectively for sunflower production.
Conventional systems of seedbed preparation consist of moldboard plowing or chisel
plowing to invert residue and several secondary field operations. Conventional systems
have been shown to increase the availability and improve the distribution of potassium
and nitrogen and to increase the seed zone temperatures. However, the risk of erosion
and expense of the several tillage operations has led to greater interest in minimum
or ridge tillage systems.
Both germination percentage and lodging have been shown to increase in ridge-till
systems vs. level plantings. Several tillage systems have been used with some success
in specific environments. Major considerations are: 1) firm placement of seed near
moist soil, 2) absence of green vegetation during emergence, 3) maintaining an option
to cultivate and 4) reduce the risk of soil erosion.
B. Seeding Date:
Sunflower can be planted at a wide range of dates, as most cultivars are earlier
in maturity than the length of growing season in most areas. In areas of the world
with no winters, sunflower has been planted at any month of the year to obtain satisfactory
yields. In northern regions, highest yields and oil percentages are obtained by
planting early - as soon after the spring-sown small grain crops as possible. In
the northern midwest and Canada this is often May 1 through 20 and mid-March through
early April in the southern USA. Resistance to frost damage decreases as the seedlings
develop into the 6-leaf stage, so too-early sowings in the northern USA or Canada
can be risky.
A later planting date tends to increase the proportion of linoleic acid in sunflower,
especially at southern locations. Damage of sunflower heads by insect larvae may
be increased by early planting. Test weight tends to decrease with late plantings.
A planting date of early to mid May is recommended in Minnesota and Wisconsin.
C. Method and Rate of Seeding:
A planting depth of 1 to 3.5 in. allows sunflower seeds to reach available moisture
and gives satisfactory stands. Deeper plantings have resulted in reduced stands
and yields. If crusting or packing of the soil is expected, with silt loam or clay
soils, a shallower planting depth is recommended.
Sunflower row spacing is most often determined by machinery available, which might
be 30 or 36 in. for corn, soybean or sorghum growers, or narrower rows for sugarbeet
growers. In Minnesota trials, sunflower yield, oil percentage, seed weight, test
weight, height, and flowering date did not differ at narrow vs. wide rows over five
plant populations. Hence, row spacings can be chosen to fit available equipment.
Row spacings of 30 in. are most common. There is evidence that earlier, semidwarf
varieties may perform better in narrower rows at high populations.
Sunflower stands have the capacity to produce the same yield over a wide range of
plant densities (Table 2). The plants adjust head diameter, seed number per plant,
seed size, to lower or higher populations, so that yield is relatively constant
over a wide range of plant populations. Trials in eastern North Dakota show increases
in yields with densities up to 29,000 plants/acre, but most studies have shown less
effect of seeding rate. Higher densities are often recommended for irrigated or
high rainfall areas.
Table 2: Effect of plant population on yield and yield components-average of 12 trials
--------- % ---------
1Non-oilseed cultivars held on an 0.8 cm round-hole screen
Plant population has a strong effect on seed size, head size, and percent oil. A
medium to high population produces higher oil percentage than does low populations,
and the smaller heads dry down faster at higher plant populations.
A lower plant population is critical for maximizing seed size for non-oilseed use.
Current recommendations in Minnesota and Wisconsin are 17,000 plants/acre (4 lb
seed/acre) for non-oilseed and 23,000 plants/acre (3 lb seed/acre) for oilseed.
Some have suggested that north-south orientation of rows produce higher yields than
east-west rows, but studies to examine this effect have found no differences in
D. Fertility and Lime Requirements:
Research has shown that sunflower responds to N, P and K. Nitrogen is usually the
most common limiting factor for yield. Nitrogen fertilizer tends to reduce oil percentage
of the seed, change the amino acid balance, and increase leaf area of the plant.
Yield increases from N fertilizer rates up to 175 lb/acre have been observed, but
rates considerably lower than this are usually recommended. Nitrogen recommendations
in dryer regions can be made from estimates of nitrate nitrogen in the soil, but
in wetter regions, this is not feasible. In the wetter regions of eastern and southern
Minnesota and Wisconsin, recommendations are based upon soil organic matter and
previous crop history. Recommendations of approximately 18 lb N/acre after fallow
or legume sod, 60 lb N/acre after small grain or soybean and 80 to 100 lb N/acre
after corn or sugarbeet are common. On higher organic matter soils, amounts should
be lowered. Nitrogen can be supplied from mineral or non-mineral sources (manures,
legumes, compost). Row placement of P and K may be important in sunflower for maximizing
efficiency of fertilizer use, as it is with many species.
More yield increases are reported as a result of applications of P than from K in
Europe and North America. Recommendations for applications of P and K should be
made from soil tests and the yield goal for each field. Recommendations range from
40 to 70 lbs P2O5 and 60 to 140 lbs K2O/acre for
soils testing very low in P or K, depending on soil yield potential. These recommendations
decrease as soil test P and/or K increase. Response to P is not expected if soil
P exceeds 30 lb/acre nor to K if the K test is greater than 300 lb/acre.
Sunflower is not highly sensitive to soil pH. The crop is grown commercially on
soils ranging in pH from 5.7 to over 8. The optimum depends upon other properties
of the soil; no pH is considered optimum for all soil conditions. The 6.0 to 7.2
range may be optimal for many soils.
E. Variety Selection:
The development of a cytoplasmic male-sterile and restorer system for sunflower
has enabled seed companies to produce high-quality hybrid seed. Most of these outyield
open-pollinated varieties and are higher in percent oil. Performance of varieties
tested over several environments is the best basis for selecting sunflower hybrids.
The choice should consider yield, oil percentage, maturity, seed size (for non-oilseed
markets), and lodging and disease resistance. Performance results from the Upper
Midwest are usually available annually from North Dakota State University, University
of Minnesota, and South Dakota State University.
F. Weed Control:
As a crop, sunflower yields are reduced, but rarely eliminated by weeds which compete
with sunflower for moisture and nutrients and occasionally for light. Sunflower
is a strong competitor with weeds, especially for light, but does not cover the
ground early enough to prevent weed establishment. Therefore, early season weed
control is essential for good yields. Annual weeds have been the primary focus of
weed control research. Perennial weeds can also present problems but are usually
not specific to sunflower.
Successful weed control should include a combination of cultural and chemical methods.
Almost all North American sunflower plantings are cultivated and/or harrowed for
weed control, and over 2/3 are treated with herbicides. Postemergence cultivation
with a coilspring harrow, spike tooth harrow or rotary hoe is possible with as little
as 5 to 7% stand loss when sunflowers are at the four to six leaf stage (beyond
cotyledon), preferably in dry afternoons when the plants are less turgid. One or
two between row cultivations are common after the plants are at least 6 in. tall.
Several herbicides are currently approved for weed control in sunflowers. Information
on chemical weed control in sunflowers is available at most county extension offices.
The most serious diseases of sunflower are caused by fungi. The major diseases include
rust, downy mildew, verticillium wilt, sclerotinia stalk and head rot, Phoma black
stem and leaf spot. The symptoms of these diseases are given in Table 3. The severity
of these disease effects on total crop yield might be ranked: 1) sclerotinia, 2)
verticillium, 3) rust (recently more severe), 4) phoma, and 5) downy mildew. Resistance
to rust, downy mildew, and verticillium wilt has been incorporated into improved
Table 3: Major sunflower diseases and symptoms.
Cottony fungus on underside of leaves. Dwarfing, contrasting discoloration of yellow-green
and green. Blackening and sometimes swelling at base of stem. Disease most severe
when rain occurs before and after emergence.
Cottony fungus on green leaves late in summer â€“ not largely damaging.
Dead blotches on flower leaves before heading. Has not caused appreciable loss.
Before heading, dead areas along leaf veins, bordered by light yellow -green margins.
Decayed vascular tissue in cross-section of stem.
Rust colored pustules on leaves, latter black specks on stems
Sclerotinia head and stem rot
Wilt soon after flowering. Light tan band around the stem at soil level. Grey-black
sclerotia (size of seed) in rotted heads and stems. Seed and meats discolored.
Phoma Black Stem
Large chocolate colored blotches on stems at maturity.
H. Insects, Pollinators, and Birds:
Bees are beneficial to sunflower yield because they carry pollen from plant to plant
which results in cross pollination. Some sunflower varieties will not produce highest
yields unless pollinators are present. All varieties will produce some sterile seed
(without meats), but varieties differ in their degree of dependence on insect pollinators.
Autogamous sunflower hybrids do not require bees for maximum yield and will yield
the same when covered by bags as uncovered. In non-autogamous sunflower varieties,
pericarp (hull) development is normal but no ovules or meat develop. Wind is relatively
unimportant in cross-pollination of sunflower. Some of the older open-pollinated
varieties such as Peredovick set only 15 to 20% of seed without pollinators, whereas
many hybrids set 85 to 100% seeds without pollinators.
Insect pests have become major potential yield-reducing factors in sunflower production
in the northern Midwest (Table 4). Insects specific to sunflower that feed on the
heads include the larvae of three moths; sunflower moth, banded sunflower moth and
sunflower bud moth. Sunflower midge has caused widespread damage in some years.
Sunflower headclipping weevil, sunflower beetle, sunflower maggot, wireworm, grasshopper,
cutworm, sugarbeet webworm, ragweed plant bug, woolybear and painted lady caterpillar
have caused occasional damage to sunflower. Adults of insect pests of other crops
(such as corn rootworm beetle and blister beetle) can be found as pollen feeders
on sunflower heads, but usually cause little injury.
Resistance to seed insects can be improved by the presence of a dark colored "armor"
layer in the seed coat. Resistance to midge has been suggested but is not currently
effective. Only currently approved insecticides should be used for control of insects.
Birds can be major pests in sunflowers. Especially important are blackbird, goldfinch,
dove, grosbeak and sparrow. Many approaches to disruption of feeding have been tried,
including scarecrows, fright owls, aluminum strips that flutter in the wind, and
carbide exploders. No techniques are 100% effective, as birds will adapt to many
of these techniques. However, in many environments, some attempt is warranted. Currently,
no chemicals are approved for bird control in sunflower.
Table 4: Common Insects in Sunflower
Eggs are laid at flowering and hatch in 1 week. Larva have dark bands running length
of body. Feeds on floral parts, tunnels in seed.
Banded sunflower moth
Moth has brown area mid-wing (.5 in.). Larvae are not dark striped, smaller than
head moth. Makes a smaller hole in top of seed, feeds on meat.
Sunflower bud moth
Dark gray moth. Larvae .5 to 1 in. in length. Feeds on young stem and head. Headless
or damaged heads or large hole on stem near a leaf petiole is symptom.
Small (.1 in.) gnat with tiny (.1 in.) cream-colored larvae laid when head is 1"
in diameter. Brown spots at base of individual florets or absence of ray flowers,
cupping of heads is symptom.
Sunflower headclipping weevil
Black weevil, about .25 in. long, causes head drop.
Adult is .25 in. long with yellow strips length of wing covers. Humpback yellow
larvae causes large areas of defoliation.
Adult a yellow fly with dark wing markings, smaller than housefly. Maggots burrow
Red sunflower seed weevil
Adult about 1/8 in. long, rusty colored, and found in head. Adult female drills
egg hole in developing seed and lays egg in hole. Larvae internal to seed; white
legless with dark head capsule.
Gray sunflower seed weevil
Adult about 1/8 in. long, gray colored; has behavior similar to red sunflower seed
Sunflower stem weevil
A robust brown and white spotted snout beetle found on the stem and in leaf axils.
It is about Â¼ in. long. Drills egg hole in stem in which it lays its egg. The larva,
a white legless larva, burrows in the stem pith. Much more abundant in drouthy sites
Sunflowers are generally mature long before they are dry enough for combining. Seed
maturity occurs when the backs of the heads are yellow, but the fleshy sunflower
head takes a long time to dry. Often, there are only a few good combining days in
October when the seed is dry enough for storage. Seeds should be below 12% moisture
for temporary storage and below 10% for long term storage. Seed up to 15% moisture
is satisfactory for temporary storage in freezing weather, but spoilage is likely
after a few days of warm weather.
Commercially available sunflower headers are useful in decreasing loss of seed as
the crop is direct combined. This equipment usually includes 9 to 36 in. width metal
pans for catching matured seed and a three-armed or similar reel. A narrower (9
in.) pan width enables harvesting diagonal to the row, which produces fewer harvest
losses in some situations.
Windrowing has been demonstrated to be effective, but probably would not be economical,
given the added cost of windrower and pickup-modifications.
VII. Economics of Production and Markets:
The cost of production and return over variable costs for sunflower is similar to
that for small grains. The culture of sunflower and growing season requirements
makes them a good niche in cropping systems where small grains are the predominant
crops. Markets are generally available in most areas where sunflower has been traditionally
grown. However, if a grower considers sunflower as an alternative crop, marketing
opportunities should be pursued prior to making the decision to grow sunflower,
particularly for non-oilseed varieties.
VIII. Information Sources:
The sunflower crop in Minnesota. 1973. R.G. Robinson. Extension Bulletin 299. Agricultural
Extension Service, University of Minnesota, St. Paul, MN.
Sunflower science and technology. 1978. Jack F. Carter (ed.). Agronomy Monograph
19. American Society of Agronomy, 677 South Segoe Rd, Madison, WI 53711.
Sunflower production in Wisconsin. 1979. E.S. Oplinger. Publication A3005, University
of Wisconsin-Extension. Agric. Bulletin, Rm. 245, 30 N. Murray St., Madison, WI
Pest control in sunflowers. 1980. J.D. Doll and J.L. Wedberg. Publication A3075.
Univ. of Wisconsin-Extension. Agric. Bulletin, Rm. 245, 30 N. Murray St., Madison,
Irrigation and nitrogen for sunflower and fieldbean on sandy soil. 1985. R.G. Robinson.
Minnesota Report AD-MR-2862. Agric. Expt. Stn. University of Minnesota, St. Paul,
Sunflower monoculture and crop rotation. 1979. R.G. Robinson, L.J. Smith, J.V. Wiersma.
Misc. Report 166 - Agricultural Expt. Stn. Univ. of Minnesota, St. Paul, MN.
Sunflower planting date: An important decision. 1985. R.G. Robinson, D.L. Rabas,
J.V. Wiersma, D.D. Warnes. Minnesota Report AD-MR-2737. Agric. Expt. Stn. University
of Minnesota, St. Paul, MN.
Sunflowers for silage in Idaho. 1986. G.A. Murray, D.L. Auld, V.M. Thomas, B.D.
Brown. Bulletin No. 652. Agric. Expt. Stn. University of Idaho.
Oil crops of the world, their breeding and utilization. 1989. G. Robbelen, P.K.
Downey, A. Ashri, eds. McGraw Hill, NY. 553 pages.