What’s next in soybean technology?

In addition to high yielding varieties, in the next few years soybean farmers will have access to more options to manage weed, insect and disease problems. Thanks to recent gene discoveries and plant breeding tools like marker assisted selection, work being done in both public (universities) and private (commercial companies) sectors will provide greater selection of high yielding soybean varieties with resistance to herbicides, drought, soybean cyst nematode (SCN), aphids and other soybean diseases.

Yield potential

Missouri soybean farmer Kip Cullers has already proven the genetic yield potential exists for soybeans to produce 150-plus bushels per acre when combined with the right cultural practices. Though not every farmer will likely attain those yields soon, average soybean yields have increased nearly 32 percent in the last 20 years and continue to improve, thanks to major investments by the seed industry, universities and the soybean checkoff.

Herbicide resistance

Among technology options coming from commercial sources are several new stacked programs, with Monsanto offering varieties that exhibit resistance to dicamba which will be combined with Roundup Ready 2 Yield^®traits, and Dow Agro Sciences providing multiple resistances to 2,4-D and glyphosate. These new options will allow growers additional choices for weed management, including fields that may have developed weed populations resistant to glyphosate, triazine, PPO and ALS inhibitor herbicides. Mike Owen, agronomy professor at Iowa State University, confirms that glyphosate resistant weeds have been identified in Iowa in at least two species, common water hemp and giant ragweed. In addition, it is also highly suspect, though not verified with final results, that glyphosate resistant biotypes of marestail also exist in Iowa; they have been confirmed in other states. “So far, these resistant weeds are scattered across the state,” Owen says, “but if we continue to rely heavily on Roundup Ready technology and glyphosate, they will become common.” Effective management techniques can minimize the continued development of weed resistance. With careful management, growers can help preserve the glyphosate technology and at least delay the spread of the problem. Owen encourages soybean farmers to consider stewardship as they develop weed management programs. He recommends using multiple herbicides with diverse modes of action.

Resistance to diseases and pests

Within the next few years, growers will also have access to soybean varieties with improved resistance to common soybean diseases and pests, thanks to the work of both private and public soybean breeders. “Resistance to sudden death syndrome (SDS) in maturity groups three through five are already pretty good, but in maturity groups one and two, the high yielding varieties lack resistance to SDS,” says David Wright, Iowa Soybean Association’s director of production research. “We can expect that to change in the near future, thanks to the efforts of plant breeders. Lines with improved resistance to SDS have been released by public plant breeders and are now in the breeding programs of several private companies.” Meanwhile, the search for new sources of soybean cyst nematode (SCN) resistance continues. “The USDA and university soybean breeders have discovered several new sources of resistance to nematodes,” Wright says. “Their challenge now is to determine whether those sources are diverse enough from PI88788, the most common source of resistance used today, to be beneficial to soybean production long-term.” In addition to soybean varieties with resistance to herbicides, SDS and SCN, soybean varieties with improved tolerance to soybean aphids will be released in 2010 by at least one major seed company. “While aphid tolerant soybeans are not immune to aphids, meaning growers and crop professionals will still need to be on the lookout for aphids as they scout for problem pests, the technology will help suppress the growth of the aphid population within the field, possibly eliminating the need for chemical treatment,” Wright says.

Seed treatments

In addition to resistance technology, growers are beginning to see an explosion in the availability of various seed treatments to control early season pests. While seed treatments are used on nearly 100 percent of corn, their use on soybean seed is a bit more complicated. “With corn, there’s a more direct impact of stand on yield,” says Palle Pedersen, ISU Extension soybean specialist. “Corn responds directly to a lower population. Therefore, treatment that increases stand directly increases yield. In addition, growers are buying corn seed by the count, meaning the loss seeds or plants from seedling diseases or insects will be very costly.” “With soybean seed treatment, we don’t always see a major advancement in terms of yield when we use a seed treatment, though there may be a slight increase,” says Vince Davis, Extension soybean specialist at the University of Illinois. “We do see a better stand, but with soybeans more plants don’t necessarily translate to better yields.” “Because soybeans can add branches to compensate for a reduced stand, there is not the same correlation between stand and yield,” Pedersen explains. “We need more research to get a better understanding of how much lower we can adjust seeding rate when using a seed treatment,” Davis says. Pedersen adds that, with the importance of earlier planting to maximize yield, the use of seed treatments is becoming more important because soybean plants are more vulnerable to problems like the bean leaf beetle and seedling diseases like Pythium that occur more frequently early in the growing season. In addition, as seed prices escalate and soybean seeds are sold by the count just like corn, the need to control early season diseases and insects becomes more important. Farmers need to protect their investment. “Seed treatments allow farmers to plant early and cut the seeding rate without losing yield,” Pedersen says. “In addition, the chance that they will have to replant is also reduced significantly.” The continued improvement in genetically-based management systems to minimize the impact of weeds, insects and disease, along with increases in genetic yield potential will enable soybean farmers to improve profitability while helping meet the increasing global demand for an affordable and safe food supply. “The challenge for soybean farmers in the next decade will not be the lack of genetically based tools to manage their production problems, but how and when to use them to maximize profitability,” Wright says. “The key to success is developing a management program that will maximize yield in each field. Growers should couple high yielding genetics featuring new traits with improved cultural practices such as early planting in narrow rows in well-drained fields with good fertility. Well-timed mid and late season management practices can make the difference between harvesting a good yield versus a great yield.”