When Roundup Ready soybeans were introduced, some observers thought STS beans would soon be phased out.
That hasn't happened, and Norm Husa doubts that it will anytime soon.
"The yield of Roundup Ready soybeans does not equal that of STS beans in our comparisons," says Husa.
As owner and operator of Husa Seed Farms, Barneston, NE, he produces certified seed of Roundup Ready, STS and conventional varieties.
STS soybeans are at this time "about as good-yielding as you'll ever find in our experience," he says.
Introduced in 1994, STS (sulfonylurea-tolerant) soybeans are considered the grandfather of herbicide-tolerant soybeans. Acreage has increased every year, reaching 5 million in 1997, then jumping to between 6 million and 8 million this year.
"The STS system captured more attention this year because of a 75% price cut of its partnering herbicides," explains Aaron Hager, University of Illinois weed scientist.
"From that respect, I think we'll see an increase in the number of acres planted," says Hager. "The future of it is hard to tell. I think the reduced cost of the herbicides associated with it will keep a lot of people interested."
More than 100 companies now offer STS soybean seed, and some are increasing supplies and offering new varieties.
Growers use DuPont's Reliance STS or Synchrony STS herbicide on STS beans.
"Both products control a very wide range of broadleaf weeds and tankmixing with a grass product completes the programs," says Fran Castle, at DuPont.
For '98, DuPont offered an Authority First-Synchrony copack for waterhemp and nightshade control.
Husa's problem weeds are velvetleaf, cocklebur and sunflower. He says he gets good control with one application of Synchrony. For grass control, Husa uses Fusion. This year, the tankmix cost him about $14/acre.
"With the technology fee we have to pay, the Roundup Ready system gets kind of expensive," Husa states. "There's a place for it, but not all places."
Weed control has been better than in his Roundup Ready soybeans, too.
"Sometimes you have to use Roundup twice because it doesn't offer residual control," he says.
According to Hager, Roundup isn't the best option for some weeds. For example, Reliance and Synchrony do a better job on smartweed and velvetleaf than does Roundup.
Some growers don't want the restrictions associated with the Roundup Ready system, he points out. Those restrictions don't exist with an STS system.
"I don't think STS soybeans are going to have as much of the market as Roundup Ready beans, but it's still a viable system for a lot of producers," says Hager.
Castle explains that the appeal of the STS system, from the beginning, has been the crop safety and proven yields that growers can achieve.
With STS beans and their accompanying herbicides, there's no crop injury, the beans canopy early and often yield better than conventional beans, according to Castle.
"I think the results speak for themselves," she says.