Recent research from Pioneer Hi-Bred, a DuPont business, is improving levels of resistance to sudden death syndrome (SDS) and soybean cyst nematode (SCN), providing growers more effective protection to help maximize yield for their soybean investment.
"Pioneer is aggressively advancing products and traits through its research pipeline at an unprecedented rate to bring higher-yielding and more agronomically stable soybean varieties to growers," says Don Schafer, senior marketing manager for soybeans.
Research efforts at Pioneer are providing new levels of tolerance to SDS. Through Pioneer characterization ratings, a grower can view levels of resistance to specific diseases for each variety. The Pioneer rating system is based on a one to nine scale, with nine being outstanding.
"Over time, our average SDS ratings for varieties in key impacted geographies have moved significantly higher," says John Soper, director of soybean research at Pioneer. "This level of resistance is unparalleled in today's marketplace."
SDS is a complex trait, causing yield losses in soybeans of 20 percent or more a year. A single gene alone does not provide high levels of resistance to SDS. Pioneer scientists stack multiple genes for stronger and more effective resistance. Molecular markers are being developed to aid the breeding in making these complex genetic stacks.
"Pioneer is putting the right combination together to maximize tolerance to the disease," says Soper. "Pioneer has a new Y Series variety, 93Y11, that has a rating of eight. There are several Y Series and M Series beans that have ratings of seven."
In recent years, SDS has had a more profound impact in the U.S., moving into high-producing soybean regions.
"The reality is, Pioneer has conducted a significant amount of research toward characterization of products into the pipeline," says Schafer. "Researchers place intense selection pressure on SDS to assure a great deal of tolerance. Varieties that don't score well in testing are removed from the research pipeline and never make it to customer fields."
Soybean cyst nematode, another key yield threat, creates losses of more than $1 billion per year. While SCN cannot be eradicated once it is present in a field, growers can select varieties with higher levels of resistance.
"SCN continues to be the most devastating soybean pest in North America," says Schafer. "We are bringing products to the marketplace for Group 0 through Group VII planting regions, and we continue to look for additional sources of resistance."
SCN is a difficult pest with several races adding to the complexity of providing resistance for growers.
"The race shift is a huge challenge and one Pioneer is concerned about," says Schafer. "Pioneer researchers are looking for alternative sources beyond PI88788 and Peking."
"PI88788 is the most common source of SCN resistance today and provides resistance to races 3 and 14," says Soper. "Peking offers resistance to a different race spectrum and has been effective in controlling emerging races 1 and 5, not covered by the PI88788 source. The general mechanism of Peking resistance, disrupting a 'feeding cell' established by nematodes in the soybean root, is the same as PI88788, however Peking provides a different spectrum of race resistance."
Even broader resistance is provided by a source known as PI437654. Pioneer is one of a very few companies to have a high-yielding variety with PI437654-type resistance with 95M60.
"We were able to develop 95M60 by using our proprietary molecular markers for SCN resistance. Our proprietary molecular marker technologies are key to developing multi-race SCN resistant varieties across all maturities," says Jeff Thompson, research scientist for Pioneer.
Growers looking for resistance to SCN can review Pioneer product characterization charts in its product catalogues. The characterization defines the source of resistance - PI88788, Peking or PI437654 - then provides a one to nine rating for all races of nematodes. Growers can compare varieties by scores or sources - based on the races for which that variety will provide protection.
"We will continue to identify and deploy new sources of SCN resistance across all maturities," says Thompson. "Growers will need soybean varieties that possess new sources of resistance to stay ahead of SCN."