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Should I Desiccate my Sunflower Fields?

Sunday, August 1, 1999
filed under: Harvest/Storage

Doing So Can Provide Definite Benefits; But Added Input Cost Can Be Difficult To Justify When Seed Price is Poor

There are several reasons why an Upper Midwest producer might want to desiccate one or more of his sunflower fields this year. In many cases, though, all those reasons likely will be over-ruled by a single reason not to desiccate: the current discouragingly low prices for oil-type sunflower and the lack of prospects for significant improvement over the next several months.

If a lot of input dollars already have been spent on weed and insect control, it’s difficult to put more into the crop, concurs North Dakota State University extension agronomist Duane Berglund. Also, if weeds are heavy, it is hard to justify a crop desiccant since the weeds already have taken a good share of the crop’s potential yield and profit. Should more be spent on an already-poor crop? The answer is a big “No!”he states.

Berglund does see instances where a desiccant could be a sound investment, however.

For northerly producers with particularly large acreage of oil sunflower, for instance, a desiccant could pay if a killing frost has not arrived by mid-October. Also, in confection ‘flowers with good contract prices, use of a desiccant is a wise decision if the crop is threatened by blackbird pressure, large heads and thick stalks that dry down very slowly, or if stalk diseases are present and the crop may be down or lodge severely.

In any given year, there are at least three key benefits derived from desiccation, according to Berglund:

*Depriving Marauding Blackbirds - Bird pressure is always a concern for many sunflower producers, the NDSU agronomist points out. By applying a desiccant, you narrow the window of opportunity for those migrating birds that feed on your sunflower crop.

*Minimizing Head Shatter - The quicker harvest occurs, the less time large sunflower heads will spend knocking against each other during windy periods. Likewise, accelerating the sunflower harvest season will prevent further deterioration of crops affected by disease.

*Reducing Weed Interference - Using a desiccant to control weeds - especially large ones like kochia and marshelder - will result in less dockage, less wear and tear on combines, and easier drying, i.e., reduced drying costs.

Gramoxone Extra (paraquat) and Drexel Defol (sodium chlorate) both carry federal labels for application as sunflower desiccants. Both can be used on either oil or confection sunflower. Each carries a seven-day preharvest interval.

Berglund says producers need to apply either of these desiccants only after the backside of sunflower heads have turned yellow and the bracts are turning brown. A seed moisture content of 33-35 percent or lower indicates the sunflower plant has achieved physiological maturity.

“Some of our sunflower hybrids now have a ‘stay-green’ stalk characteristic; so go by the heads or seeds,” Berglund advises. “Another means of telling whether physiological maturity has occurred is to rub the chaffy material on the front of a sunflower head. If it rubs off easily, the plant is physiologically mature.

The North Dakota agronomist suggests any producers planning to apply a desiccant to their sunflower this fall first check the herbicide label; or, consult the NDSU Extension Service 1999 North Dakota Weed Control Guide for details. The guide is available at the following web site:

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