Time to Try Desiccation?

Desiccate for improved quality plus risk and time management.

Natural sunflower dry down can be slow and uneven. Desiccants decrease losses due to inclement weather, lodging and bird depredation by speeding up the dry down process. 

Alison Pokrzywinski, sunflower technical agronomist for Nuseed, says she’s also a fan of desiccation. “If a grower doesn’t desiccate then they are at the mercy of Mother Nature waiting for a hard frost to kill off the plants. Sometimes growers are waiting until October or November for that to happen.” Pokrzywinski provides three important reasons for growers to desiccate:

  • Disease – with late-season stalk disease you want to get the crop off as soon as possible to prevent further stalk damage.
  • Peace of mind – the earlier the crop is in the bin, and not at the continued mercy of late-season environmental conditions, the more peace of mind for the producer.
  • Blackbirds – these pests can settle into a field two weeks after petal drop and once established, it’s hard to get them to leave. Getting the crop off earlier is the best solution to a difficult problem.

Desiccant Timing and Products 

Desiccants can be applied to the crop once plants have reached physiological maturity. At this stage (R-9), the back of the head turns yellow, the shoulders of the bracts turn brown and seed moisture is about 35 percent. Applying desiccant before physiological maturity may reduce test weight and seed quality.

Desiccation products for use on sunflowers include glyphosate; Gramoxone® (paraquat), which is known as Reglone in Canada; Drexel Defol® (sodium chlorate), which is only registered in the U.S.; Sharpen® (saflufenacil), which is known as Heat® in Canada; and Valor (flumioxazin), which is only registered in the U.S. Always follow registered uses on the product label.

One of the big differences in desiccation products is speed. Usually growers can start harvesting approximately three weeks after applying glyphosate. Alternatively, products like Gramoxone (Reglone in Canada) and Drexel Defol work faster allowing growers to harvest about 10 days after application.

However, another important difference that Pokrzywinski points out is that products like Gramaxone and Drexel Defol will remove the waxy layer on the back of the sunflower heads, whereas glyphosate will not. This waxy layer prevents water absorption into the head if it rains. “If you get rain a couple days after spraying, the sunflower head is going to absorb water and you could be waiting longer [to harvest] than if you hadn’t sprayed,” says Pokrzywinski.

Growers can typically harvest sunflowers 10 to 14 days after applying a tank mix of Sharpen and gylphosate, she adds.

When considering desiccation as a harvest aid, growers should factor in planting date, weather, typical hard frost date and market.

“You have to weigh your odds on what the weather’s like, your potential for a hard freeze, when you planted and how much time you have. For example, are you going to be waiting for a hard frost for 30 days or more?” asks Pokrzywinski.

“The other part to consider is what the price of the crop is, and what market you’re going into. Those in a higher value specialty market, like confections, want the highest quality to get the best price they can.”


Here’s what growers have to say about the importance of desiccating sunflowers: 

Steven Beakley | Ennis, TX 

Efficiency and speed. These are the two biggest reasons Texas producer Steven Beakley chooses to apply a desiccant to his sunflower crop as a pre-harvest aid.

“We desiccate primarily for a cleaner, more uniform harvest,” he says. “We always have some fields around sensitive areas we’ll save for last and let dry down on their own, but just to speed harvest and for uniformity, desiccation works better for us.”

It’s been a decade since Beakley planted his first sunflower crop for the oil market on his 7,400-acre farm near Ennis in Ellis County. He includes roughly 2,000 acres of sunflowers annually to add some diversity to his cotton, corn and wheat rotation.

“It’s a good rotation for weed control as the herbicide rotation keeps the resistant pigweed in check. Wheat seeded after sunflowers does well for this part of Texas,” he says. “Plus being dryland and so dependent on rainfall, the sunflowers seem to take the dry years better than other crops.”

Travis Iglehart | Garrison, ND

Before he tried it, Travis Iglehart thought desiccating his sunflower crop was a waste of money. “I was the guy who said, ‘just let the frost get it.’ I tried it one year, and now I won’t go a year without it,” he says.

Iglehart, who grows roughly 3,000 sunflower acres near Garrison, North Dakota for the oil, confection and dehull markets, says the benefits of getting the crop off early with the help of a desiccant far outweigh the input cost.

“A desiccant kills the plant so you can harvest it sooner. The earlier you harvest, the less damage from birds and you get the crop off before the snow comes,” says Iglehart. “You also get a drier crop that is a lot easier and faster to combine. It’s an additional expense but it saves money in the long run,” he says.