Nail Down Seed Choices

October 1, 2010 11:41 AM

The long line of pickups and cars filing down the dusty country road appears like a scene out of “Field of Dreams.”

In farm country, field days are as much a rite of summer as baseball. For farmers like Allen Sasse of Beason, Ill., scouting for new hybrids and varieties is still one of the best ways to develop a seed lineup for the coming season.

“As seed becomes more expensive, it’s even more important to scrutinize the selections,” Sasse says. He likes to try new technology, but the company also matters. “I prefer to deal with firms that stand behind their seed with good replant policies,” he adds.

Each summer, 7,000 to 8,000 people show up for Becknology Days, a cross between a field day and a festival, hosted by Beck’s Hybrids in Atlanta, Ind. There are activities for the entire family, but the event centers around a healthy serving of learning opportunities for growers, says Scott Beck, vice president of the company.

“We build the days around agronomy tours that look at herbicide plots and tillage comparisons. This year, we had a sub-irrigation/tile irrigation study that was very informative,” he says.

Tom Burrus of Burrus Hybrids, in Arenzville, Ill., says the social aspect is enjoyable but that it has become increasingly important for seed companies to offer farmers more than a good pork chop to win their loyalty. “With the explosion of product choices and technology, growers can be confused as to which products work best on their farm,” he says.

Hybrid sensitivity to chemicals and new recommended refuge choices are examples of information his company shares with growers.

“When advising growers how to select products, we often start with the herbicide program to be used. That narrows down the catalog significantly. Then we look at the genetic families that fit their soil type and planting population within the right maturity range. Technology—disease resistance and rootworm or corn borer protection—is next,” Burrus says.

“We also look at how the product is packaged and seed treatment needs. The final part is selecting the correct refuge hybrid to protect the technology.”

Check the data. Joe Lauer, an agronomist at the University of Wisconsin, agrees that local field days and company trials are helpful, but he urges growers to search as well for third-party verification and multiyear data from universities and independent advisers.

“If a hybrid fails in a trial, make sure you understand why,” Lauer says. “Next year’s environment cannot be predicted, but a hybrid that performs consistently is much less likely to disappoint you.”

Lauer says growers should avoid loading up on technology just because it’s new. In many areas of the U.S., typical corn-soybean rotations may not need a corn rootworm (CR) trait, for example.

“Where western corn rootworm variant or the northern corn rootworm with extended diapauses is present, growers should think hard about using Bt-CR technologies to manage these insects,” Lauer says.

“Today’s seed costs require a sharp pencil. Good corn can be grown without transgenic technology if you supply the right management. Using technology only on fields that really need it can help you trim costs,” he adds.

“It’s a privilege to grow these hybrids,” Lauer says. He recommends farmers shepherd the technology by rotating herbicides and insect protection.

Don’t assume a hybrid will perform simply because it belongs to a certain family tree. “There are interactions between genes that get transferred in the transgenic process,” Lauer says. “Just because a hybrid is in a genetic family doesn’t mean it will be a home run.”

Find the right match. Field days offer a first look at what companies have to offer each year. “Choosing the right hybrids and varieties is one of the few things a grower has control over,” Burrus says. “Be sure to pick a seed company that listens and offers you more than a free lunch.”
That means developing a relationship with suppliers who are able and willing to help you identify the seed technology best suited to your farm.

Sometimes, because of genetics and agronomic factors, the best option for your farm isn’t necessarily the racehorse seed product, says Joe Bruce, general manager for F.I.R.S.T. Seed Tests.

“Our mantra is select hybrids and varieties that provide you with consistent above-average yields,” he says. “The emphasis is on consistency.”

Research indicates that with many of today’s genetics, farmers can score consistently higher corn yields by boosting seeding rates.

Farm Journal Associate Field Agronomist Missy Bauer says seeding rates per acre should be about 5% higher than the final plant population you want to achieve.

Farmer Terry Finegan is evaluating four hybrids this year with plant populations between 32,000 and 34,000 seeds per acre depending on hybrid and soil type.

He says most farmers in his area near Jonesville, Mich., shoot for final plant populations that are in the upper 20,000s to 30,000 per acre.

University researchers also see populations trending higher in Iowa, Illinois and Minnesota.

Optimum populations. Roger Elmore, Iowa State University Extension agronomist, says the plant population research he has conducted with colleague, Lori Abendroth, across 32 Iowa sites, indicates maximum grain yields occur between 34,500 and 37,000 plants per acre, depending on soil fertility and weather conditions.

Elmore adds that for optimum profitability, growers must balance yield goals against seed prices and the price paid for corn.

“The best net returns here in Iowa occur with corn plant populations between 30,000 and 35,000 plants per acre,” he says.

Emerson Nafziger, University of Illinois Extension agronomist, shares a similar outcome based on 35 trials he conducted in northern Illinois and 36 trials in southern Illinois.

“The optimum plant population using a seed price of $3.50 per thousand seeds [$280 per unit] and a corn price of $3.50 per bushel was about 33,500 plants per acre in northern Illinois and 27,300 plants per acre in southern Illinois,” he says.

“In both cases,” he adds, “optimum plant populations were some 3,800 plants per acre lower than the populations needed to maximize yields. That seems like a lot, but it’s a flat part of the response curve, which means those extra plants didn’t produce enough yield to pay for the extra seed.”

Jeff Coulter, an University of Minnesota Extension agronomist, has developed resources that can help you calculate the seeding rates needed to obtain various corn stands based on expected emergence, as well as plant populations (see table below).

Wisconsin’s Lauer recommends that growers start the process of increasing plant populations slowly.

FJ 028 F10285“Boost your seeding rate by 10% in part of a field, then at harvest measure the yield of that portion of the field against the rest of the field,” Lauer says. “Depending on the results, adjust seeding rates accordingly the next year.”

Along with evaluating final yield, Lauer says, farmers need to evaluate the crop during the growing season for any negative impact caused by higher plant populations. He says to look for uneven plant sizes, tillering, lodging and barren ears.

Extension specialists say not to be concerned if kernels do not form in the top 1⁄2" of an ear. In fact, if kernels have formed to the tip of the corn ear, it means that particular field could have handled a higher plant population.

Support your plants. Agronomists vary on whether there is a direct correlation between higher fertility levels, particularly nitrogen, and increased yields from higher plant populations. Research at the Farm Journal Test Plots indicates that there is a correlation.

“You want to be careful how you push those populations,” Bauer says. “You’re feeding more plants, so you need sufficient nutrients, especially nitrogen and potassium, to support those higher yields.”

Steps in the Hybrid Selection Process

1. Begin with trials in zones nearest your farm.
2. Compare hybrids with similar maturities within a trial.
3. Evaluate consistency of performance across zones and years.
4. Compare performance in other unbiased trials.
5. Consider hybrid performance for other traits—for example, standability, drydown rate, grain quality, etc.
6. Base your decision on more than one or two local test plots.

Diagnose Abnormal Ear Development

As farmers walk through their corn fields one last time this fall, breaking ears off stalks and shucking husks to expose the yellow grain inside, many are less than pleased with what they see. In many cases, the top portions of the corn ears are void of kernels; in others, strips of empty cob form zipperlike patterns down one side of the ears.

This agronomic issue is commonly referred to as corn ear tipback. It results from the stress that the crop encountered during the growing season, says Missy Bauer, Farm Journal Associate Field Agronomist.

“The tips of the corn ears pollinate last, so they’re the part of the plant that is most susceptible to a lack of kernel fill when the plant encounters stress,” Bauer explains.

Nutrient deficiencies, disease, insect feeding and clipping, excessive heat, drought and even consecutive days of cloudy conditions are all factors that can contribute to ear tipback.
This season, an insufficient amount of nitrogen and higher-than-normal temperatures at pollination were the two primary contributors to tipback, Bauer says.

“Heavy rains caused nitrogen to leach from the soil profile and impact early corn growth,” she says. “High temperatures that held steady during pollination, especially at night, reduced the crop’s ability to pollinate and contributed to kernel abortion.”

Bauer says that differentiating between tipback that is caused by nutrient deficiency and tipback that is caused by excess heat can be something of a challenge.

“When you see ears with a lack of kernel fill on one side of the cob or a very uneven kernal fill at
the top of cobs, those are indications that your corn had a nutrient deficiency,” Bauer says.

“Ear tipback due to heat and drought usually results in a more consistent loss by row around the top of the ear,” she adds.

While farmers can’t control the temperatures in their fields, they can address the problem of early-season nitrogen loss. Bauer says she encourages farmers to test their corn crop during silking next season, at about the R1 stage, to determine whether additional nitrogen is needed to support crop growth and to apply accordingly.

—Written by Rhonda Brooks

You can e-mail Pam Smith at or Rhonda Brooks at

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