Sunflower production isn’t likely to displace corn anytime soon, but advancing technology is giving sunflower growers better hybrids and herbicides, making it a much more profitable crop.
Because markets for both oil and confectionary sunflowers have been growing and are projected to see increased expansion, the crop is quickly becoming a consistently stable source of income.
Add to that soil science findings about how corn and sunflowers aid each other’s growth when they’re in the same crop rotation, and it might be worth taking a second look at how this flower fits a no-till system.
Keeping Plants Cool
Former National Sunflower Association president Tom Young says sunflowers are currently the best cash crop in his central South Dakota 100% no-till system. His rotation includes spring wheat, winter wheat, corn and sunflowers. Young began working with his father “Gil” in the 1970s to grow sunflowers in Sully County.
Since 1989 he’s kept sunflowers in his crop rotation, currently producing about 1,200 acres of flowers annually on 5,000 acres of cropland. Every acre is dryland.
He notes that Sully County is the largest sunflower-producing county in the U.S. and with the exception of drought years, South Dakota has consistently increased its sunflower yield average.
The county yield average is around 1,700 pounds per acre, and the state average is now about 1,600. Young says he’s seen yields over 3,000 pounds per acre in some of his fields and the annual average is between 1,800 and 2,000 pounds.
Weather conditions — hot and dry — are compatible with sunflower production. However, late July and early August temperatures in Young’s location can reach 100 degrees or more.
To avoid having plants flower during July’s hottest temperatures and risk yield reduction, Young schedules planting times during mid to late June. His maturity group selections vary from Group 2 through Group 5. Maturity dates for his sunflowers are similar to 100-day corn in order to obtain the best possible yield while avoiding excessive heat and early frost.
Young says Mycogen’s 8H449CLDM variety, which offers Clearfield herbicide technology and provides genetic resistance to downy mildew pathogens, has worked well.
When it comes to planting, confectionary sunflowers have a larger seed contained inside a thicker, larger hull. To obtain consistent emergence and a satisfactory stand, Young uses a John Deere 1770NT 24-row planter equipped with vacuum seed meters, Martin openers, and a KE Precision Ag hydraulic down pressure system. It’s the same planter he uses for corn. His per-acre sunflower population is 22,000.
“Some growers use air seeders, or the same drills used to plant wheat, and that can work. But I use a corn planter because I want sunflowers to emerge in a picket-fence-perfect row,” Young says. “Sunflowers, unlike corn, will compensate for a population gap if some come up later than others.
“You don’t want a train wreck for a stand, but in the right environment late emerging sunflowers generally produce a similar stalk and head size by harvest.”
Seeds are planted at an average depth of 2 inches. The larger hull of confectionary sunflowers requires ample moisture in order to penetrate the hull. If soil moisture is low, Young’s seeds may lie in the dry dirt for a few days before rain stimulates germination.
Because Young’s sunflowers are planted between the previous year’s corn rows, residue isn’t much of an issue. However, Martin row cleaners in front of his planter push away excess residue that might prevent adequate seed-to-soil contact. Young sets the row cleaners to lightly adjust any residue buildup while avoiding deep soil disturbance.
Feeding the Crop
In the past, young often broadcast fertilizer for his sunflowers, but more recently he’s been placing dry fertilizer in the sunflower row, or near the vicinity of the plant roots.
He wants to avoid accelerated decay of residue that can occur when fertilizer is broadcast, and also believes sunflowers can more readily access nutrients placed closer to their root system.
“One thing about fertilizing sunflowers is that you don’t want fertilizer close to the seed because it can burn it and stop germination,” Young says. “Like any large crop, sunflowers utilize a lot of nitrogen.
“Also, because of the sunflower’s stalk style, phosphorus and potassium are important. In order to accurately assess fertilizer needs, we annually test three to five zones in each field in order to plan variable rate fertilizing.
“We also use soil-test results to manage variable population in different field zones. We don’t want to over fertilize, but we know if we have high yield we may have to fertilize more heavily the subsequent year. Through soil testing we know for certain plants have the food they need.”
New Weed Threats
Because no-till is Young’s primary weed control tool, he sees few weed issues in his sunflowers. However, in recent years, kochia, pigweed and Canadian thistle have posed some challenges.
He relies on a pre-emergent herbicide program to avoid the majority of weed issues.
“Starting with a clean seedbed is key to successfully managing weeds,” Young says. “I start with a glyphosate Herboxone-type pre-emergence product. If I use a Clearfield variety, I can use Beyond herbicide for post-emergence weed broadleaves and some grass. I’ve found pre-emergence use of Spartan and Prowl H is the most effective approach.”
Insects that concern Young include the sunflower midge, sunflower beetle, sunflower stem weevil, read and gray sunflower seed weevil and banded sunflower moth.
Tarnished plant bugs and Dectes stem borer have also been identified as pests in the Dakotas. Young diligently scouts for weevils, treating infestations with an aerial application of DuPont’s Asana XL if necessary.
“I’m always scouting for weevils at bloom time,” Young says. “Anything that attacks confectionary sunflower seeds is serious problem since there’s little tolerance for pest damage with a human edible.
“Recently developed seed treatments really help with flea beetles. Managing them would be much more difficult without that advance in seed technology.”
Typically, Young doesn’t see either sunflower rust or fungicide problems, although sunflower rust can decrease head size, oil content and yield if present.
Cool, moist conditions can support spread of rust. Because the disease occurs readily on wild sunflowers, spores can be spread to cultivated hybrids through the wild flowers or other susceptible weed species.
While he hasn’t observed much fungal infection in his sunflowers, Young says experience has taught him that using BASF’s Headline fungicide at bloom time, during R1 to R3 growth stage, has improved plant health and vigor.
Until recently, Young used a corn head to harvest sunflowers, but he purchased an Italian-made sunflower head from Fantini, an Italian company that recently opened a U.S. Corporate office in Le Center, Minn.
BIG PEST. Downy mildew has been one of the most devastating sunflower diseases affecting growers and sunflower profit. New downy mildew resistant hybrids are helping growers better manage the disease and protect crops and profit.
“This head does a great job of saving seeds during harvest,” Young says. “If the seed is overly dry, it will save seeds that do shatter. It’s very similar to a corn head except it’s designed to handle a lightweight crop like sunflowers, which only weigh about 20 or 30 pounds per bushel.”
As much as he can, Young aims to leave sunflower stalks intact during harvest. In his no-till system, the standing residue helps catch snow and protect soil form wind and water erosion.
He stores most of his seed into the winter, when contractors are ready for delivery.
Boosting a Rotation
Dan Mock and his brother Anthony primarily raise corn sunflowers soybeans and wheat on their south-central North Dakota land in Emmons and Kidder Counties.
For 20 years, on their 6,400 dryland acres, the Mocks have raised about 1,600 acres of sunflowers. For the same amount of time they’ve used 100% no-till.
Among the benefits of their sunflower crop are the diversity it brings to their rotation, and the distribution of labor at planting and harvest.
“The only trouble we’ve encountered with a rotation of wheat, corn and sunflower is the need for a fourth crop, because we can only plant sunflowers every fourth year,” Dan says. “That’s why we’ve added soybeans to our rotation in the last couple of years.”
The Mock’s sandy soils aren’t ideal for soybean crops. However, the brothers prefer adding soybeans to planting corn-on-corn because of the residue issues continuous corn poses for planting sunflowers.
While they have run cattle on corn stalks and sometimes removed a portion of the stalks to mix with feed for their feedlot animals, the Mock brothers still found adding soybeans to be the most acceptable crop rotation solution.
“With back-to-back corn, we also faced a long haul to the ethanol plant if we didn’t have enough bin room at harvest time,” Dan says. “That was an unacceptable demand for labor that doesn’t fit well in our operations.”
Considerations for Seeding
Sunflower planting time can come as early as May for the Mock brothers. Corn planting is completed first, with sunflowers following the previous year’s corn crop.
If weather delays corn planting, sunflower planting is deferred, too. If weather conditions greatly hamper corn planting, the Mocks have the option of planting additional sunflower acres in order to get a crop in the ground.
The brothers appreciate the seed-placement capabilities of their John Deere 1770NT planter, which is fitted with the Dawn RFX+ hydraulic down-pressure system and a Dawn trash wheel. The Dawn RFX system is sensitive to the variable contour of their fields, helping secure seed-to-soil contact. Row width for their sunflowers, and all their crops, is 30 inches.
“We plant between the old corn rows, so the ground is typically warm and dry at planting time,” Dan says. “We also avoid most residue issues that way. We’ve found that leaving corn stover as tall as possible helps reduce residue concerns. If corn stalks are attached, they’re not going to be chewed up by the combine and pile up on the soil.”
The Mocks have also seen heavy corn residue negatively impact newly emerged sunflowers during a major rain or wind event. Significant movement of the residue can clip small sunflowers off at ground level until plants reach heights of 6 inches more.
Liquid fertilizer is applied at planting. Although it slows the planting process, it reduces labor hours and potential soil compaction. Soil testing in each field’s hilltops as well as flat and low zones allows the Mocks to organize an effective and economical fertilizing program.
They’ve found that increased yields from precise fertilizer placement more than compensate for soil testing costs.
“We get more bang for our buck by placing fertilizer more precisely near the seed bed,” Dan says. “Sunflowers go after nutrients more aggressively than some other crops, but it makes sense to make fertilizer easily accessible. And soil testing is king when it comes to precise fertilizer programs.”
To take the guesswork out of variety selection, the Mock’s rely on test plots in their region to see actual growth and yield results of different sunflower varieties.
They also thoroughly explore seed-cost options through their dealer to take advantage of available discounts on bundling corn and sunflower seed purchases. In recent years, Mycogen sunflowers have performed well for the Mocks and fit their contract requirements.
“We look for the closest test plot with soil and field conditions that are a best match to our operation,” Dan says. “We usually plant more than one variety each year and try to find two or three that shine on our farm. We do a lot of research to review the traits of different varieties in regard to how they perform in specific soil conditions and how they handle disease and drought stress.”
Anthony serves as the agronomist on the Mock farm as he deals with disease, pesticide and insecticide strategies. The family battles the same types of weevils and beetles seen in South Dakota, controlling pests with pyrethroid mixes that Anthony varies from year to year to avoid resistance issues.
Spartan herbicide is part of their pre-emergence weed management plan. Selection of sunflower varieties with the Clearfield seed technology helps with post-emergent weed control.
“For the most part, our fields are really clean because of our no-till practices, so weeds aren’t a big issue,” Anthony says. “”We always have volunteer corn and some volunteer wheat.”
The Mocks usually deliver their sunflower seeds at harvest. Retaining them in bins requires constant ventilation during storage. Most companies they contract with take at least a portion of the sunflower seed at harvest and the remainder soon after.
They found the Fantini combine head to be effective when they had downed sunflowers but have been using a John Deere straight head with sunflower pans in recent years.
Synergies With Corn
Don Tanaka, retired soil scientist with the USDA’s Northern Great Plains Research Laboratory at Mandan, N.D., says there is a synergistic relationship between corn and sunflowers that can induce a yield increase in both the corn and the sunflowers when the two are included in a rotation.
While he doesn’t completely understand what happens between the two plants, scientists believe both corn plants and sunflower plants can utilize the same root channels in a field, and, perhaps, the same mycorrhizae as they mature.
“Especially when sunflowers follow corn, they seem to use the corn root channels to send taproots down,” Tanaka says. “That means the sunflower expends less energy to develop a root.
“Corn plants have a high proportion of mycorrhizae and some of that hairy fungal system remains in the soil when corn is harvested. It’s possible that sunflower roots are more quickly infected by the residual corn mycorrhizae so the roots grow at a faster pace than if the sunflower had to produce its own mycorrhizal system.”
Because sunflower residue is dark colored, it could aid in spring soil warming, he adds. Corn planted into sunflower residue is likely to emerge faster and be able to utilize the sunflower root channels during root development.
Since corn produces ample residue, evaporation in a corn-sunflower rotation would reduce the percentage of moisture lost to evaporation at the soil surface.
While sunflowers require ample water, they could also improve soil aggregation - which means larger soil pores allow melting winter snows and early spring rains to channel down 1 to 2 inches below the soil surface, protecting moisture from evaporation.
“Because corn is a warm season grass and sunflowers are a warm season broadleaf, the rotation can help break corn pest and disease cycles, especially root worms,” Tanaka says.
“If wheat is in the rotation, the sunflowers also help reduce wheat pest and disease cycles. It’s not easy to get those two types of crops into a rotation, which makes corn and sunflowers another good combination. The other key benefit is that sunflowers add crop diversity, which is one of the first ways to improve soil health.”
A Final Word
Young encourages farmers with an interest in sunflower production to consider their farming operation as a system, paying attention to clean fields at sunflower planting time and intensive weed and insect management.
Some past perceived disadvantages of sunflowers include depletion of soil moisture and deep nutrient removal, putting subsequent crops at a nutritional risk.
“There are other crops that use some deep nutrients,” Young says. “But sunflower does it better than anything else. However, it’s still our best consistent income.”