Four
out of every five animals on earth today is a nematode so it is not
surprising that agricultural fields are home to many nematode species.
Fortunately, most nematodes are beneficial to crop growth and soil
health because their activities help decompose crop residues and cycle
nitrogen and other nutrients. Pest nematodes do not threaten yield if
their numbers remain low. The key to avoiding population explosions of
nematode pests is to be proactive – know what the situation is and take
appropriate measures when nematode numbers indicate a problem is
brewing.
The
WSMB sponsors free nematode testing to help producers stay ahead of the
most important nematode pest of soybean, the soybean cyst nematode
(SCN) (Figure 1). Eggs of SCN persist in the soil between soybean crops
so a sample can be submitted any time that is convenient. The soil test
report indicates the number of eggs in the sample and is useful for
selecting the right variety for the next soybean crop. Retests of fields
planted with SCN-resistant varieties over multiple years shows how the
nematode population is responding to variety resistance and provides an
early warning should the nematode population adapt to host genetics.
 |
| Figure 1. WI Counties Confirmed to Have SCN as of 2013. |
In
2016, the WSMB is again offering the expanded nematode testing program
to include other pest nematodes in addition to SCN. These nematodes are
less damaging to soybean than SCN but can cause enough yield loss to
warrant treatment. As is the case for SCN, there are no rescue
treatments for nematodes so the primary purpose of this year’s soil test
is to plan for next year’s crop. Soil samples collected in corn for
nematode analysis have predictive value for explaining yield if they are
collected before the corn V6 growth stage. Sampling early in the season
will provide information about the risk potential for the current corn
crop AND the next soybean crop.
The
assays used to recover nematode pests other than SCN in soil require
that the nematodes are alive. So, it is important to keep the samples
moist and at least room temperature cool. Collecting a sample that
includes multiple cores ensures that there will be plenty of root pieces
to assay. It is not necessary to include live plants in the sample. The
soil test report will indicate which pest nematodes are present and at
what quantities and their damage potential to soybean and corn based on
the numbers recovered.
Free soil sample test kits are available now and can be requested at (freescntest@mailplus.wisc.edu).
Free soil sample test kits are available now and can be requested at (freescntest@mailplus.wisc.edu).
For
more information on SCN testing and management practices to help reduce
the losses from this pest, please contact: Shawn Conley: spconley@wisc.edu; 608-262-7975 or visit www.coolbean.info.
Remember
the first step in fixing a nematode problem is to know if you have one!
The WSMB sponsored nematode testing program provides you that
opportunity.
