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GROWERS ARE doing a much better job choosing sophisticated soybean varieties that fight yield-robbing pests. That's the good news. The bad news is that far too many growers still buy bean seed on the cheap, and it's costing them — big time.

In Iowa, growers are losing as many as 60 million bushels a year to soybean cyst nematode alone, says Iowa State University agronomist Palle Pedersen. “It's the most yield-limiting pathogen in Iowa,” he says. He adds, however, that “breeders have done an outstanding job in stepping up to the plate and getting us SCN-resistant varieties.”

A better buyer

You can become a more intelligent buyer by taking the following steps before writing a check to your soybean seed salesperson:

  • Look at replicated yield data from numerous test sites.

  • Go back to the farm and identify yield-limiting factors that can be managed by variety selection.

  • Lastly, and only then, look at price.

Growers may be reluctant to ante up for top-yielding varieties because, “in the past, soybeans have been the cheap commodity [seed] product,” says Bob Navratil, head of technical services for NK Brand.

“True, the more bells and whistles you get with your seed obviously means the varieties are going to cost more,” Pedersen says. “But don't focus so much on price.” Instead, you will be dollars ahead if you focus on high yields and the disease resistances you need.

Check the data

There is no shortage of data on yields; seed companies, universities, even lending institutions now test yields of soybean varieties, notes Dan Dyer, global head of product development for Syngenta. But wading through the data is no easy task, he admits, because “all the data are accurate, but they don't agree with each other.” The test data nonetheless allow you to narrow the list of candidates to a few top performers.

Dyer emphasizes that you need data from multiple sources so you know it's accurate. For example, a company may say in a seed brochure that its variety out-yielded the competition in 500 trials, but what it probably does not say is that the competitors may have their own data that may contradict those yield trials. To choose the right seed, Dyer recommends you have a relationship with a seed sales representative you can trust and to buy from an organization with applied research.

Don Schafer, product line manager of soybeans for Pioneer Hi-Bred International, says that while there appears to be hundreds of confusing choices, you can whittle down the list fairly quickly. Pioneer has more than 100 different soybean seed products, for example, but no more than 15 or 20 would fit an individual farm.

Emerson Nafziger, University of Illinois agronomist, says most growers hedge their bets and plant several varieties from three or four different companies. While it makes sense not to just plant one variety, the importance of planting several varieties from different companies may be exaggerated. “Once in a while, a variety is so good that planting one third or even 50% of it is not such a bad idea,” Nafziger says.

Although you may think you are buying different varieties from different companies, the seed may actually be quite similar genetically. If you truly want to plant varieties with different traits, Nafziger suggests you choose varieties with different characteristics such as different maturities. Planting varieties with different maturities is a good idea because each year has different climatic conditions and growers need the ability to stagger harvest, he says.

Experts say there is no correct number of different varieties any grower should plant because every farm — or even field — is different. For one grower with 900 acres of soybeans and multiple soil types, the number might be six or seven varieties with different characteristics, such as drought-tolerance for light soils. For another grower with 900 acres of fairly uniform soils, five or six different varieties might make the most sense.

Nafziger advises farmers to collect yield data on varieties on multiple locations, including locations up to a hundred miles east and west to match maturities of where they are located. Illinois data suggest that earlier- and later-maturing varieties, on average, for a specific zone do not do as well than those that mature in middle ranges. Early varieties can be hurt by drought and later ones can be hurt by early frosts or poor late-season conditions, Nafziger says.

One reason why growers should not plant the same set of varieties every year, Nafziger says, is that “pathogens are always changing,” meaning that “variety resistance is a moving target.”

The key diseases growers in Illinois have to be concerned about when choosing seed, he says, are soybean cyst nematode, sudden death syndrome, white mold and brown stem rot.

Yield drag

Nafziger is concerned that a grower might focus so much on finding varieties with traits resistant to plant diseases that he loses sight of yield. For example, a new variety with multiple resistance is likely to be a product of backcross breeding and therefore it could have “yield lag” due to the time it took to develop it, or “yield drag,” which refers to a physiological cost (often lower yields) to the plant for resistance.

That's why it's important to identify your most important pest problems, says Iowa State's Pedersen. In his view, you should target the two most yield-limiting pathogens in a specific field to be sure you don't give up much in yield. “If a variety is resistant to four or five pathogens, it often won't be high yielding,” he states. In Iowa, the top two yield robbers are soybean cyst nematode and sudden death syndrome.

Syngenta's Dyer thinks resistance to two pathogens is too conservative. He says that with today's sophisticated breeding, yield drag won't kick in until growers are choosing varieties that are resistant to four to six different pathogens. He says it takes two or three cycles of breeding “to get the junk out,” so there is no yield drag.

He adds, though, that it might be worth giving up a small amount of yield potential to eliminate a big yield-robbing pest from crashing yields on a particular field with serious pathogen problems.

Match traits to fields

Of course, not every grower will benefit from the new crop traits. For example, Dyer says, “there is a lot of talk about soybeans low in linolenic acid, but for most people, nobody will be paying a premium for growing them in their market area.”

However, Walter Mayhew, soybean product manager for Asgrow, says that value-added soybean varieties such as its Vistive varieties (with low linolenic acid) give growers the option to receive premiums of up to $0.40/bu. He says that growers can choose a Vistive variety with soybean cyst nematode and Phytophthora root rot resistance without giving up any yield potential. There may be times, however, that a grower may have to decide whether to choose disease resistance or buy the highest-yielding variety. “A grower has to ask whether it's economically feasible,” he says.

Mayhew points out that one big mistake when buying soybean seed is to look at varieties and conclude that 1 to 2 bu./acre is not a lot of difference. “One to two bushels times $5 to $7 beans over a lot of acres is quite a bit of difference,” he says.

Pioneer's Schafer says that, to make intelligent seed-purchasing decisions, growers need to know their fields, but as farms have become larger “growers don't know their fields as well as they used to. Good records are key.” He adds that growers are going to need different seed varieties based on their cultural practices. If a grower plants no-till beans in cool soils in April, the fields may need a fungicide treatment.

He advises growers to ask hard questions about new seed varieties: “Just because it's new doesn't mean it's the best thing for an individual farm.”

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