Ames, Iowa
December 15, 2008
Source:
Integrated
Crop Management News,
Iowa State University
Extension
By Greg Tylka and Chris Marett, Department of Plant Pathology
http://www.extension.iastate.edu/CropNews/2008/1208tylka.htm
Harpin protein is a natural plant compound that can stimulate
plant defense responses. And N-Hibit™ is a seed-treatment
containing harpin protein that is sold in the United States for
management of the soybean cyst nematode (SCN). Iowa State
University Extension evaluated the effects of N-Hibit™ seed
treatment on soybean yield and SCN population densities in nine
field experiments located throughout Iowa in 2007 and in nine
different field experiments in 2008. The work was supported by
the soybean checkoff through funds from the Iowa Soybean
Association.
In 2008, the experiments were conducted in Laurens, Mason City
and Winthrop in northern Iowa; Gowrie, Nevada, and Urbana in
central Iowa; and Council Bluffs, Hills, and Malvern in southern
Iowa.
|
Figure 1. 2008 Experiment
Locations |
 |
In both years, an SCN-susceptible
and an SCN-resistant variety were grown at each experiment, and
the seeds of each of the two varieties were either left
untreated or were treated with N-Hibit™ at a rate recommended by
Plant Health Care Inc.,
the distributors of the product. All of the plots were four
17-foot-long rows spaced 30 inches apart. There were four
replicate plots per variety-seed treatment combination, and 16
plots total per experiment. The center two rows of each four-row
plot were harvested with a plot combine, total seed weight per
plot and seed moisture were determined, and total plot seed
weights were converted to bushels per acre.
Soil samples were collected from the plots to determine the SCN
population densities. Ten soil cores were collected from the
center two rows of each plot immediately after planting and
again at the time of harvest. SCN cysts were extracted from a
100-cc subsample (a little less than a half cup) of each soil
sample, and SCN eggs were extracted from the cysts and counted.
The yield results from all experiments and the end-of-season SCN
egg population densities from three of the nine locations are
presented in the table below.
| Table 1. 2008 Results
- N-Hibit™ seed treatment experiments in nine Iowa
locations. |
 |
In 2008, N-Hibit™ did not
significantly affect the yield of the SCN-resistant or the
SCN-susceptible soybean variety at any of the nine experimental
locations. But overall, yields of the SCN-resistant varieties
were significantly greater than the SCN-susceptible varieties in
the experiments at Council Bluffs, Malvern, Mason City, and
Urbana.
At this time (early December 2008), the final (end-of-season)
SCN population densities are available only for three of the
experiments (Gowrie, Hills, and Winthrop) conducted in 2008. In
those experiments, there was no significant difference in final
SCN egg population densities in plots of SCN-susceptible or
SCN-resistant soybean varieties left untreated or treated with
N-Hibit™ . However, at all three locations, there were
significantly greater final SCN population densities on the
SCN-susceptible soybean varieties than the resistant varieties.
In the experiments conducted in 2007, N-Hibit™ had no effect on
yield of the SCN-resistant soybeans at any of the experiments
and no effect on yield of the susceptible soybean varieties at
seven of the nine locations. Yields of N-Hibit™ -treated
susceptible soybean varieties were 2.1 and 3.0 bushels per acre
greater than yields of untreated soybeans at the Melrose and
Urbana experiments, respectively, in 2007.
When the end-of-season SCN egg population density data are
obtained for all nine of the experiments conducted in 2008, a
revised report of this work will be published in Integrated Crop
Management News that will include all nematode data from 2008
and also a combined analysis of yield and SCN egg population
density data from all 18 experiments conducted throughout Iowa
in 2007 and 2008.
Greg Tylka is a professor of plant pathology with extension
and research responsibilities in management of plant-parasitic
nematodes. Chris Marett is an assistant scientist with
responsibilities for research on the biology and management of
the soybean cyst nematode.
This article was published originally on 12/8/2008 The
information contained within the article may or may not be up to
date depending on when you are accessing the information.
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