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Harvest Early if Lodging Looms

Saturday, September 1, 2001
filed under: Harvest/Storage

Harvest Early if Lodging Looms

Some producers in the High Plains had problems with stem weevils in sunflower this growing season. Producers who didn’t treat for them should consider harvesting early to avoid lodging, advises Ron Meyer, Colorado State University extension agronomist, Burlington.

“They should consider taking them at 14% moisture, turn the bin fans on, and they will easily dry fast down to 10%,” Meyer says. “Sunflower down here tends to dry down fast naturally. One time we started harvesting a field in the morning and it was 12% moisture. That afternoon they were down to 8% moisture. Our fall humidity levels around 15% combined with afternoon air temperatures near 75 degrees or warmer make for good conditions to naturally dry sunflower.”

An all-crop header works best for picking up lodged ‘flowers, says Vern Hofman, North Dakota State University extension ag engineer. “I also like narrower catch pans in those situations too, because you can go different directions across the field and they help you pick up a few more heads. If they’re solid seeded, then put lifter fingers on the tips of the header to help pick up the lodged heads.”

Read more about how a Nebraska producer mounted PVC pipes on his combine header to pick up lodged sunflower, on the National Sunflower Association web site, Click on The Sunflower Magazine link, then “the archives.” The September, 1998 article, “Long PVC Fingers Cheap and Effective Answer to Lodging,” is under the equipment section.

Joe Harner, Kansas State University ag engineer, anticipates warm, dry conditions for sunflower harvest this year. “It may get a little warmer than normal, and producers will have to run the fans to cool sunflower down.”

Harner recommends that sunflower in the High Plains harvested at less than 12% moisture should have aeration (natural air, low temperature drying) of at least ¼ cfm/bu; sunflower harvested at 12-15% moisture aerated using ½ to 1 cfm/bu; and above 15% moisture, 1 to 2 cfm/bu. When sunflower is put in the bin above 15% moisture, Harner recommends filling the bin about two thirds full, cooling and drying it, then filling the rest.

Meyer advises sunflower producers to keep combines free of chaff and fines that can cause fires. “Last year we had a number of combine fires. In Kit Carson County we had four combines burn up. Crop moisture can get so low here that it doesn’t even register on the moisture meter, and when you get sunflower that dry, you’re going to have fire potential when harvesting sunflower. One strategy for producers with fields that are too dry is to harvest at night when humidity is higher. And always keep the machine as clean as possible, especially near the motor. Some seasoned sunflower producers keep fire extinguishers available to quickly address combine fires. But the best advice is to harvest damp, at 10% moisture or above. Fields that came off at those moisture levels last year didn’t have fire trouble.”  Tracy Sayler

Estimating Field Loss At Harvest

The harvested yield of sunflower can be increased by making necessary adjustments following a determination of field loss. Three main sources of loss are: 1) loss in the standing crop ahead of the combine; 2) header loss as the crop enters the machine, and 3) threshing and separating loss.

Loss occurring in any of these areas may be estimated by counting the seed on the soil surface in a square foot area. Ten seeds per square foot is approximately one hundredweight (cwt) per acre loss if seed loss is uniform over the entire field.

The loss in the standing crop is estimated by counting the seed in a one square foot area ahead of the machine at several different places in the field.

Header loss can be calculated by counting seed in a one square foot area behind the head under the combine and subtracting the standing crop loss.

The loss in combine separation can be found by counting the seed in a one square foot area directly behind the rear of the combine and subtracting the shatter loss and the header loss found under the machine.

The count made directly behind the combine will be concentrated, so an adjustment must be made to equalize the loss over the entire width of cut. The result should be divided by the ratio:

Width of Header Cut (feet)


Width of Rear of Combine (feet)

The answer is the adjusted separator loss for the width of cut. This result must be divided by 10 to obtain the combine separator loss in cwt per acre. The total loss in cwt per acre is determined by adding the seed loss in the standing crop, header loss, and separator loss, and dividing this answer by 10. The percentage loss can be found by dividing the total cwt per acre by the yield in cwt per acre.

Harvest without some seed loss is almost impossible. Usually a permissible loss is about 3%. Loss as high as 15 to 20% can occur with a well-adjusted combine if the ground speed is too fast, resulting in machine overload.  North Dakota State University Extension Service

When To Consider a Sunflower Desiccant

If bird pressure is severe, disease levels are high, or lodging problems are occurring, the use of a harvest-aid desiccant for sunflower may be considered when the crop is mature and an early harvest would be an advantage.

Early drydown of sunflower plants may also slow or stop development of head rot and reduce sclerotia and destruction of seeds. However, warm sunny days following a desiccant application is needed to give the best results. Indeed, grower experience indicates head rot may actually get worse when wet weather follows desiccation compared to green fields left untreated. Thus, weigh the weather probabilities and the advantage of early harvest compared to the risk of wet weather following desiccation.

Desiccation can also reduce head shattering, control weeds (especially large weeds like kochia and marshelder, resulting in less dockage and less wear and tear on combines) and ease crop drying with reduced drying costs.

Two types of desiccants can be used. These include paraquat (Gramoxone Extra) and sodium chlorate (Defol) for use on oilseed and confectionary sunflower. Allow a minimum of 7 to 10 days prior to harvest to get maximum killing and drydown of the sunflower. Read and follow the label for rates and adjuvants to use.

Apply either desiccant by air after the back of sunflower heads have turned yellow and the bracts are turning brown. Physiologically mature sunflower plants have a seed moisture content between 33 and 35%. Some sunflower hybrids now have a stay-green stalk characteristic, so go by the heads or seeds. Another way to tell if 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.  Duane Berglund, North Dakota State University extension agronomist

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