Features Agronomy Harvesting
Sunflowers: making the grade

Growing sunflowers can be a challenge, but investing time and attention to this special crop can be very profitable for growers.

Fred Parnow, Canada business manager for NuSeed America, says if you can grow a number one quality confection sunflower crop, you will always find a market. "Confection sunflower can be more financially rewarding than most other commercially grown crops if grown correctly and managed correctly. If you take care of the crop, you'll be rewarded."

But these tall, beautifully flowering plants need a lot of attention. During a presentation at the CropConnect Conference in Manitoba in February, Parnow said that to grow a premium grade product – plants with large seeds containing larger kernels with an oil content of 34 per cent by volume – for the confection market will provide the grower with a $600 to $800 total return per acre. However, the precise management of the crop is crucial to success.

Precise management begins with precision planting. Anastasia Kubinec, oilseeds crop specialist with Manitoba Agriculture, Food and Rural Development (MAFRD), says seeding should take place in May even though there's still a risk of frost. Seedlings will emerge between one and three weeks after planting, depending on the soil temperature at planting. Kubinec says the seeds germinate/emerge faster once the soil temperature is above 10 C, but the minimum temperature for growth/development occurs at 6.7 C.

Sunflowers are fairly frost tolerant when emerging and at the two-leaf stage. During this early growth stage, plants can withstand temperatures between minus 3.3 C to minus 3.8 C for short periods. As plants develop two, four, six or more leaves (V2-, V4-, V6 stages), they become progressively more sensitive to frost and terminal bud damage can occur. At these stages they can only withstand minus 1.6 C to minus 2.2 C temperatures for a short time.

Both Kubinec and Parnow agree seed spacing is crucial for producing high quality sunflower crops, and the final plant population per acre determines what market the seeds can be sold in. The more plants per acre, the smaller the heads and resulting seeds. Smaller seeds with an oil content of 43 per cent by volume are desirable for the oilseed market, while the confection market demands seeds that meet a designated industry size standard (too large to pass through a 22/64 screen).

The ideal seed drop for the crop destined for the confection sunflower market is 17,500 seeds per acre, placed 1.5 to two inches deep, approximately a foot apart with 30 inches between rows. This seeding pattern will produce a final plant stand per acre of 15,000 to 16,000 plants. The final plant stands for oilseed type sunflowers varies, depending on the market being targeted. Final populations when targeting bird food can be as high as 24,000 plants per acre, for the oil market final populations of between 22,000 and 23,000 are desired, and crop destined for the dehull market, bakeries and food processors should be 20,000 plants per acre.

The preferred equipment for placement of sunflower seed in the field will depend on the type of sunflower. For precise depth control, a row crop planter is preferred over an air seeder to ensure accurate seed placement for confection sunflowers. An air seeder or drill will work for oilseed type sunflowers that are typically solid seeded, but it is less precise.

Weeds, insects, disease and fertility
After planting and until emergence, growers need to closely monitor their fields. As the sunflower plants emerge, they're immediately susceptible to damage from weeds, according to Parnow. "They'll never catch up because the weeds take too much away from the young plants," he says.

While cutworms pose a threat to emerging plants, lygus bugs and the banded sunflower moth are the two most problematic insect pests in sunflower. Lygus place a secretion onto the kernel on the inside of the seed, discolouring the kernel, while the banded sunflower moth larvae burrows into the seed and devours the kernel either completely or partially, leaving a foul flavour behind.

Kubinec recommends four to seven years between sunflower crops to reduce incidence of sunflower rust, phoma, phomposis and verticillium wilt. Sclerotinia head rot and sclerotinia stalk rot damages can be reduced by a four year or more break between sunflowers and another sclerotinia susceptible crop, such as canola or dry bean in the individual field and the adjacent field to reduce transfer of inoculum that has built up. She adds cereal crops, such as wheat, oats and barley, make the best neighbours for sunflowers. Damage from sclerotinia can cause decreases in market prices and yield, and potentially leave harvested product unsaleable.

Weather and birds also cause damage but there's nothing the farmer can do to control either. Weather just happens, and Kubinec notes red winged blackbirds have a voracious appetite for sunflowers and are clever enough to learn to ignore the "boomers" or "cannons" farmers place in fields in an attempt to drive them away. Troy Turner, with the National Sunflower Association of Canada, says the best way to discourage the birds is to eliminate cattails growing anywhere within a half mile of the sunflower fields.

Sunflowers, like other crops, need nutrition. Parnow says manure application is not the preferred method of fertilization for sunflowers. "It seems manure applications inherently lead to disease issues in the field." This is unique to sunflowers, unlike other crops such as corn, he adds. Traditional fertilization is the recommended method of providing nutrients to sunflower crops. Proper nutrition starts with soil testing and an understanding of the nutrient needs of the crop (nitrogen, phosphorus, potassium and sulphur) in order to produce the desired yields.

Harvesting
Harvest generally occurs in September, but even at this stage, the crop is still vulnerable to damage. Cool, wet weather from mid-August through September can delay development. This means the grower has to watch the crop to determine when it reaches the stage where it's ready for desiccation treatments, when the "backs of the heads are banana yellow and bracts are brown to the shoulder," according to Turner. Once a desiccant is applied the waiting begins again. It will take 10 to 14 days, or up to three weeks before the entire field is ready for harvest. Warm, dry weather will help; wet cool weather will simply prolong the process. Desiccation has to be complete before harvest begins or the equipment will encounter green stalks, and instead of cutting them cleanly will push stalks down and heads will be missed.

September to early October is the best time for harvest but once again, it's all about the weather. And after all the watching and waiting for a uniform drydown on the field, even more patience is required to ensure the entire crop gets into the combine.

Parnow says a harvest speed of five miles per hour is the top rate for the equipment when harvesting sunflowers. Kubinec adds there's a specialized header for cutting the crop and a header projection or guide that guides the heads into a specific line to be cut all at once and moved into the combine. If the machinery is moving too fast, heads will not be cut off the stalks and the plant will fall over instead of being beheaded. The angle of the header is also important so the cut heads and seeds actually slide down into the opening of the combine to be threshed rather than falling off the header and lost.

"Confection sunflowers can provide amazing revenues but it does take a lot of management and potentially there are higher risks than with some of the other crops like wheat," Kubinec says.

Parnow adds: "If you take care of the crop you will be rewarded."

May 11, 2016  By Anne Cote