Every year, plant spacing in sunflowers remains one of the two top yield-limiting factors and is therefore an issue that growers need to take very seriously.
“Depending on the year, plant spacing is either the number one or two issue based on the USA Sunflower Survey,” notes Trygg Olson, Field Sales Leader at Nuseed Americas. “The survey is conducted in seven states across the country including North Dakota, South Dakota, Minnesota, Kansas, Nebraska, Colorado and Texas. Looking at the survey in 2013, 209 fields were surveyed and plant spacing was the number one issue causing yield loss with over 25% of the fields. This was followed by disease and drought. In 2015, plant spacing came in at number two with 13% of the 201 fields surveyed, while disease was the most limiting. Jumping ahead to 2019, which was an extremely wet year throughout the northern growing region of N.D., S.D. and Minn., disease was the number one factor limiting yield followed closely by plant spacing at nearly 20% of all fields surveyed. We always hear about blackbirds destroying crops and killing yield, but from 2013 to 2019, out of 715 fields surveyed, in only 4 to 8% of these fields’ yield loss was due to blackbirds while 16 to over 25% were caused by plant spacing.”
While disease, drought and blackbirds are something growers have little control over, if any, plant spacing is a factor that growers have complete control over.
And, as Olson explains, there are many tools available to use to help set up producers’ planters. Some of these include operator’s manuals, National Sunflower Association (NSA) resources, equipment dealers and seed suppliers. “These are all great sources of information available to find the right plates and settings to get started,” says Olson. “Secondly, we need to look at the equipment itself.”
Over time, planter plates will wear, causing the orifice to get too large to pick up a seed or causing it to pick up multiples, resulting in skips and or doubles. Alison Pokrzywinski, a Technical Agronomist and Nuseed Sunflower Product Manager, North America, notes that research on the yield and quality losses associated with skips or doubles in sunflowers is being investigated at the U.S. Department of Agriculture Sunflower Genetics Lab, led by Dr. Brent Hulke in Fargo, N.D.
“His preliminary research is showing that sunflowers are very good at still maintaining yield in the presence of variable stands, but the lack of uniformity does affect the quality of the stand,” says Pokrzywinski. “A lack of uniformity brings about issues of increased disease (Phomopsis for example) where there are multiple plants fighting for the same space. The micro-environment with increased plants creates a more disease-friendly environment and the smaller stalks makes it more likely to lodge.” Dectes stem borer are also more likely to do devasting damage to those plants that have smaller stalks by completely lodging over in the fall.
Coming back to planter plates, Olson says, “We also need to keep in mind the brushes can also become worn and will not perform as intended. While we look at the planting equipment, we will need to look at the whole planter. One needs to make sure that the machine is operating in a smooth fashion.
Look at bearings to make sure they are in good shape, and drive chain and sprockets to make sure there are no frozen links and there is smooth rotation while turning. If the rotation is tough or jerks while rotating the drive tire, it will be an indicator of where an issue may be – a place to start looking.” He adds that a little time checking things over and prepping machines properly will put everyone a step closer to achieving high quality and profitability.
Uniform plant stands also promote the best results for insecticide spraying during bloom and carries through to harvest to provide even drydown for desiccation timing or harvesting (if you didn’t desiccate). “Having an even plant stand is the best recipe for success when it comes to making sizing grades,” Pokrzywinski adds. “Seed size is incredibly important for conoil and confections where the seeds need to fit over a certain size screen.”
She adds that sunflowers will typically flex their head size based on the space allowed. “The more space they are given, the larger the heads,” she explains, “and the closer the plants, the smaller the heads size. It’s often a balancing act in sunflowers, aiming to find the perfect population that will bring forth yield, excellent standability and meeting the processor requirements for your end market. For confection sunflowers this typically means a lower population with larger heads, aiming for large seeds that will be sold for the in-shell market.” Growers for the bird food market need to meet a minimum 28 pound test weight requirement and some- times too low of a population can bring that test weight down too far.
“Setting planting populations aside, no matter what market the sunflowers are being sold into, establishing a good plant stand with very few doubles or skips is the ultimate goal and key to starting off a successful growing season,” says Pokrzywinski. “Every- one always talks about yield and quality loss as it pertains to confection sunflowers, but in oilseeds, whether for crush or bird food, yield and quality also matter and plant spacing is key.”