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Is Your Sunflower Ready for Winter Storage?

Thursday, November 1, 2001
filed under: Harvest/Storage

Is Your Sunflower Ready for Winter Storage?

If you put $10,000 in the stock market, you’re obviously going to check your investment periodically to see how it’s doing. If you put $10,000 worth of sunflower in the bin after harvest, you’re obviously going to check your investment periodically to see how it’s doing—right?

Unfortunately, that’s not always the case. “I see some pretty substantial losses sometimes where people just seemed to ignore the fundamentals,” says Ken Hellevang, extension ag engineer at North Dakota State University.

One fundamental rule is to verify that your sunflower is at the right moisture content for winter storage. “So many things can fool our moisture meters, so do a moisture check after you place seeds in the bin to make sure moisture is where you want it to be,” says Hellevang. It’s not uncommon for sunflower removed from the dryer at 8 to 9% moisture (according to the moisture tester) to climb up to 11 or 12% moisture by the next morning. The moisture rebound can be estimated by placing a sample from the dryer in a covered jar and rechecking the moisture after 12 hours.

Oil sunflower should not be stored above 10% moisture during the winter and 8% during the summer. Confection sunflower should not be stored above 10% moisture during the winter and 9% during the summer. Sunflower can be stored for short periods at 12% moisture with adequate airflow to keep the seeds cool.

Insects become dormant after grain is cooled below 50 degrees, and grain cooled to below 40 degrees usually prevents mold growth. Grain should be cooled to 20 to 25 degrees for winter storage. “Cooling sunflower is the best insect control method that we have. If we can cool the grain to around freezing and hold it there over winter, we’re not going to have any insect problems,” says Hellevang.

Large pieces of head, stalk, and corolla tubes, which frequently adhere to the seed, should be removed from stored sunflower, since this chaff is higher in moisture than the seed. Keep in mind as well that sunflower containing a high percentage of hulled or immature seed tend to deteriorate in storage, affecting oil quality.

Fines and weed seeds smaller than sunflower tend to concentrate in the center of the bin, and this area tends to be higher in moisture and more prone to storage problems. Airflow will also be restricted by the fines, limiting cooling by aeration. If you recognize fines and weed seeds as a potential storage problem, you may wish to consider “coring” or auguring out that center of the bin to remove the material. “It’s a decision each grower will have to make. If you have little weed seed and fines, you may not have to do that. If you do have that, then coring the bin is an option to consider,” says Hellevang.

An air space should be left in the top of the bin to facilitate checking the condition of stored seed. Bins should be checked initially every two weeks for moisture content, condensation on the roof, crusting, and for changes in temperatures within the pile. Any of these conditions could indicate the presence of mold or insects. If the pile has started to heat, the pile should be cooled immediately. The sunflower should be checked at least monthly after desired temperature and moisture content for winter storage has been reached. Be sure to cover fans and ducts after the grain has been cooled for winter storage to prevent snow from blowing into the bins. – Tracy Sayler


Confection Concerns: Preventing Insects, Dark Roast

Live insects and dark roast (the burnt, off flavor of kernels) are two common problems that can result from improper storage of confection sunflower. “Once it’s in the bin, those are probably the two things we run into most as far as storage problems. It’s either not cooling (the seeds) down properly or having something in the bin that’s not dry, and having moisture migration,” says Dean Pedersen, a purchasing manager and agronomist with Agway Inc., Grandin, N.D.

An ounce of prevention, as the saying goes, will go along way to preventing confection sunflower storage problems. That includes adequately cleaning and preparing bins before filling them, and drying and cooling sunflower properly for storage.

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