Des Moines, Iowa
November 1, 2007
Soybean growers now have more
options when selecting soybean varieties that have high yield
potential and the ability to stave off soybean cyst nematodes
(SCN). Pioneer Hi-Bred, a
DuPont business, continues to expand its lineup of SCN-resistant
soybean varieties, providing growers a choice in rotating SCN
sources in their fields to keep potential resistance issues in
check.
Soybean cyst nematode, the single most damaging pest of soybeans
in the United States, continues to move northward from the
southern U.S. and has reduced yields on tens of millions of
soybean acres. All major soybean-producing states are affected,
and the economic impact is more than $1 billion every year.
Using Multi-Sources for SCN Resistance to Maintain
Effectiveness
"SCN cannot be eradicated from a field, even when soybeans are
removed from the rotation," says Jeff Thompson, research
scientist for Pioneer in Mascoutah, Ill. "This means the goals
for soybean growers are to maintain soybean yield, reduce SCN
numbers and preserve the effectiveness of resistance soybean
varieties."
Just as alternating herbicides with different modes of action
helps prevent weed resistance from developing, agronomists and
university experts recommend planting soybeans with different
sources of SCN resistance.
"In the past few years, we have seen more cases of nematodes
reproducing in fields planted with varieties using the
traditional source of resistance (PI 88788) which is deployed in
many Midwest varieties," says Greg Tylka, Iowa State University
plant pathologist, specializing in soybean cyst nematode,
biology and management research.
"For many years, PI 88788 has been the main source of resistance
used to control SCN, but by using this source as a primary
control, there have been cases where nematode control has not
been as effective," says Tylka. "While these reports have been
isolated, they are increasing in number. Reports of PI 88788
resistance being overcome and signs that SCN continues to spread
north have certainly encouraged the development and expansion of
SCN-resistant varieties."
The Peking source has not been widely deployed in the Midwest.
However, Pioneer researchers, using sophisticated molecular
marker technology, have integrated Peking SCN resistance into a
number of high-performance soybean varieties. Marker-assisted
selection (MAS) allows Pioneer breeders to track the genes
associated with resistance and increases their effectiveness in
combining yield with SCN genes. Selecting for resistance markers
makes the breeding process both faster and more efficient.
"In addition to the source of resistance, the genetic background
also plays a role in a variety's ability to control SCN," says
Thompson. "Rotating resistant varieties is often a good strategy
for controlling an SCN population."
Determining SCN Levels in the Field
"Growers can experience SCN damage and not realize it - making
SCN an extremely difficult challenge to manage," says Tylka.
"There can be as much as 30 percent to 40 percent potential
yield loss due to SCN damage below ground, but the plant
actually can look healthy above ground. Therefore, growers may
attribute yield loss at harvest time to other factors during the
growing season."
Tylka encourages growers to consider either soil sampling or
examining root systems to determine if SCN is present. There are
several factors to keep in mind for both management tools. Soil
sampling is more costly, but can be done nearly anytime of the
year, and once a baseline is determined, soil sampling can be
spread out to every six to eight years. Examining root systems
is virtually a no-cost option, but can be done only at certain
times during the growing season - July or August.
"Growers need to know that besides waging a costly battle on its
own, SCN also can intensify other yield-reducing diseases for
soybeans," says Tylka. "Research shows SCN can worsen soilborne,
fungal diseases such as sudden death syndrome (SDS) and brown
stem rot (BSR). Keeping SCN numbers under control also can
benefit growers by limiting the impact of other diseases."
While research has focused mainly on yield loss caused by SCN,
now the focus is starting to shift to determine the potential
quality damage. According to Tylka, Iowa State University, with
soybean check-off funding, is exploring if SCN has an impact on
soybean composition, such as oil or protein content. With the
ever-increasing production of specialty crops, including low
linolenic and high oleic soybeans, retaining desired composition
is a key end result.
New SCN Resistance Varieties for 2008
"Maintaining adequate soil fertility, reducing compaction, and
controlling weeds, diseases and insects all improve soybean
growth and plant health," says Thompson. "These practices help
soybean plants compensate for SCN damage, however, they do not
decrease SCN numbers and are not a substitute for practices such
as rotating crops and selecting the right SCN-resistant
varieties," adds Thompson.
To help growers address the challenge of SCN, Pioneer is
expanding its lineup of soybean varieties with multi-sources of
SCN resistance to include products across a wide geographic area
in 2008 - including northern and central areas of the Corn Belt.
The following are new Pioneer® brand soybean varieties with SCN
resistance:
- 90M80 is a Group 0 variety
that not only has the Roundup Ready® (RR) gene, but also the
Peking source for resistance against SCN, giving Minnesota
customers the ability to address the northern movement of
SCN.
- 91M80 (RR) is a new Group
I variety offering excellent performance and solid SDS
tolerance in northern areas.
- For early Group II, both
92M11 and 92M21 have the RR gene and the Peking source for
SCN. These products will be offered across a large area in
2008 - from Iowa to Minnesota and east to Michigan and
Ontario, Canada.
- 93M61 (RR) in mid-Group
III is a new product for soybean growers looking for SCN
resistance in more central Corn Belt areas from Kansas and
Nebraska in the West and to Pennsylvania and Maryland in the
East and is setting the standard for performance in
mid-Group III.
For further information on soybean
varieties that help you harvest the greatest profits from your
fields, contact your local Pioneer sales professional.
Pioneer Hi-Bred, a DuPont business, is the world's leading
source of customized solutions for farmers, livestock producers
and grain and oilseed processors. With headquarters in Des
Moines, Iowa, Pioneer provides access to advanced plant genetics
in nearly 70 countries.
DuPont is a science-based products and services company. Founded
in 1802, DuPont puts science to work by creating sustainable
solutions essential to a better, safer, healthier life for
people everywhere. Operating in more than 70 countries, DuPont
offers a wide range of innovative products and services for
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from Monsanto Company |
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