Features Agronomy Corn
Narrow row sunflower production possible

In Manitoba, the majority of sunflower acres are row cropped for several reasons.
Many sunflower growers also grow dry beans and corn and have the necessary row
crop planters to take advantage of precise seeding. In addition, around 80 percent
of the Manitoba sunflower crop is the confection type, which has very high quality
standards for seed size and colour. While it is not impossible to grow confection
sunflowers with narrow row spacings, it becomes more difficult.

"With an air-seeder, you get bunches of seed randomly placed in the seedrow.
Where seeds are placed too close together, the plants compete for space and
light, resulting in smaller heads and smaller seeds," explains Rob Park,
oilseed specialist with Manitoba Agriculture, Food and Rural Initiatives (MAFRI)
at Carman. "And when the seeds are spaced too far apart, you get big heads
and delayed maturity. Those problems impact on seed size and quality."

For oilseed sunflowers, though, those hazards are not as insurmountable. The
goal with oilseed sunflowers is to grow high yield with high oil content. Grower
experience in Manitoba and research in North Dakota shows narrow row oilseed
sunflower production is possible.

12 inch rows yield the highest for oilseeds
North Dakota is the biggest sunflower producer in the western US. A key difference,
though, is that about 80 percent of the production is oilseed sunflowers and
20 percent non-oil: the opposite of Manitoba. That is the reason that narrow
row sunflower production generates interest in North Dakota. It is a crop that
growers can get into without specialized equipment.

Researcher, Burton Johnson at North Dakota State University at Fargo recently
re-visited narrow row sunflower production. It was initially considered as far
back as the 1980s, but very high plant populations were targetted and success
was variable. Since then, hybrid sunflower production has evolved and advances
in air-drill technology and weed control make solid seeded production look more
favourable.

The research was conducted at Casselton and Minot, North Dakota, for three
years and compared row spacings of six, 12, 18 and 30 inches, along with plant
populations of 18,000, 22,000 and 26,000 plants per acre for the oilseed hybrids
Interstate 6111 and Cargill 187. The 12 inch row spacing consistently provide
the highest yield response. The 30 inch spacing was the poorest, and the six
and 18 inch row spacings were similar. In four of six years, the 12 inch row
spacing yielded 33, 37, 24 and 16 percent greater than the 30 inch row spacing.

The trend for plant populations favoured the lowest rate; 18,000 was better
than 22,000, which was better than 26,000 plants per acre. In three of six site
years, the 18,000 plant population yielded 11, 25 and nine percent more than
the 26,000 plant population. The benefits of lower plant population were most
pronounced at Casselton. However, excessively low plant population can reduce
crop value by reducing seed yield and oil content. Plus, large heads from low
populations may require longer to dry down and may be difficult to harvest,
although seed moisture differences were not seen in this study.

Regarding oil content, Johnson says there were some differences between row
spacing and plant populations, but he did not believe there was enough difference
to be concerned.

Less clear for confection
Non-oilseed hybrids Pioneer 6946 and Red River Commodities 2331 were grown at
plant populations of 14,000, 18,000 and 22,000 in the study. For these non-oilseed
sunflowers, Johnson says the research was less clear. Surprisingly, row spacing
did not affect the percentage of seed size over a 20/64 sieve. However, he did
see larger seed at the Red River Valley site compared to the typically drier
Minot site. "That makes me wonder why we, in North Dakota, shouldn't be
growing confection types in wet areas and oilseed in drier areas," Johnson
ponders.

Plant population also had no effect on yield for the non-oilseed trials. And
row spacing by plant population interaction was not significant for yield, seed
oil and percentage seed over a 20/64 sieve.

At this point, Johnson is hesitant to make a recommendation for row spacing
with confection sunflowers. The trials used hand-weeded plots, which may have
impacted the results. "I think the jury is still out on row spacing for
non-oilseed sunflowers. I would like to see more research before making a recommendation,"
says Johnson.

What about Manitoba?
In Manitoba, Park says that experienced growers are making solid seeded confection
sunflowers work on their farms. "They do it and they do it very well, but
they started out growing oils."

Park says that in Manitoba, solid seeding is typically done on row spacings
of 10 to 15 inches for both confection and oilseed sunflowers. He says that
regardless of row spacing, plant population should remain the same as that recommended
for wide spacings. Oil-type plant populations should be targetted at 20,000
to 22,000 plants per acre, or about 0.6 plants per square foot. For confection
type, seeding rates should not exceed 18,000 plants per acre or 0.4 plants per
square foot.

"If you are a canola grower and you are used to seeing nice, solid rows
of canola, seeing sunflowers emerge can be a tough pill to swallow. The plants
are so far apart," says Park. "You can drive a truck around the field
for a long time without hitting one. You have to be real patient until the crop
is about knee-high."

Park says that if growers are going to experiment with solid seeding with an
air-drill, they might as well stick with 10 inch row spacing if they have it.
Seed distribution in the rows appears to be better, which aids in faster canopy
closure and better weed competition. Several post-emergence grassy weed herbicides
are registered in sunflowers, but broadleaf control must rely on pre-emergence
products.

"When you take away inter-row tillage in wide rows, the big challenge
becomes broadleaf weed control in sunflowers," says Park.

The decision to try solid seeded sunflower production will ultimately be dictated
by seeding equipment. If row planters are available, they appear to be a good
bet for confection sunflowers. For oilseed sunflowers, based on the North Dakota
research, solid seeded sunflowers shows great promise, provided weed control
issues can be figured out. Park adds that since sunflowers are not heavy users
of nitrogen, he expects Manitoba acreage to be well above average along with
oats, flax and soybeans. -30-