Published on Friday, August 19, 2016
This is an exciting time of year as many of our kids head back to school and those of us walking fields anticipate solid corn and soybean yields following a year of adequate rainfall and soil moisture.
At times rainfall was excessive, dew periods were long, and there were “perfectly timed” drops in air and soil temperatures at critical the stages of crop development that caused a “not so exciting” thing to look at in our soybean fields.
Sudden Death Syndrome (SDS) in Soybeans
We are observing foliar symptoms and pre-mature death caused by SDS in portions of some Missouri soybean fields. The most common occurrence is in fields with a history of SDS in 2014 and those fields that were planted early this year (the last week of April or the first week of May). Figure 1 below shows a FARMserver™ profile for temperature and rainfall for a field near Perry, MO. Note the drop in air temperature and increase in rainfall toward the end of April and beginning of May when many early beans were planted. Also note the drop in temperature and increase in rainfall at the end of June/beginning of July. This corresponds to when many of the early planted soybeans were transitioning to the reproductive growth stages.
Figure 1. Temperature and rainfall this season near Perry, Mo.
The timing of this weather pattern with early-planted soybean growth and development created the “perfect storm” for SDS, especially in fields with a history of the disease.
SDS is a two-phase disease. The soybean roots are infected early with the SDS fungus (Fusarium virguliforme) which is followed by the production and movement of toxins up into the leaf tissue (see Figure 2). This typically occurs with cool, excessively wet conditions at the reproductive growth stage.
Figure 2. Foliar symptoms of Sudden Death Syndrome
Ultimately, the leaves die and drop off leaving the petiole attached to the stem. The stem and plant both prematurely “die”, hence its name the name Sudden Death Syndrome.
I have observed an increase in severity of SDS in more poorly drained soils and in drainage areas where much of the excessive rainfall was moving but had no way to get off quickly (due to soils already being saturated in those areas and repeated rainfall). Interestingly, the severity is also greater in planter overlap areas. It has also been my observation over the years that when SDS "hits", severity trends worse in more productive soil areas of a field (see Figures 3 and 4).
Figure 3. Severe SDS in planter overlap in northeast Missouri.
Figure 4. Aerial imagery of the same field shown in figure 3. Severe infection in planter overlap, wet and higher productivity areas in northeast Missouri. Image provided by customer.
Once infected, there is nothing we can do to remediate affected field areas.
However, there are things we can learn and adjust to mitigate SDS risk in the future:
Fields or field areas with a history of SDS should not be planted early. It is best to wait until after Mother’s Day to plant fields with an SDS history.
Select soybean varieties with a greater tolerance for and/or resistance to SDS. When selecting and placing soybean varieties on your fields be sure to note their SDS scores. All soybean varieties can be infected with SDS. Some are scored "higher" because they have demonstrated greater tolerance during an infection event.
Have your soybean seed treated with Escalate SDS for any fields you plan on planting early. This treatment adds the ILeVO® fungicide to Beck’s standard Escalate™ yield enhancement system for an additional layer of protection against SDS. Again, this is especially important if planting early on fields with a history of SDS. A good management strategy may be to treat one third of your soybean seed with ILeVO and use that seed on the acres that you will plant earlier than your average soybean planting date. To add Escalate SDS to your soybean seed, contact your local seed representative.
Improve drainage and reduce soil compaction. Capital improvements to your land that improve drainage and water infiltration such as tile installation and applying organic amendments (manure to improve soil structure and tilth, etc.) can help water to shed off of the crown of the soybean plant during its reproductive phase and reduce the rate of colonization of the fusarium fungus at the root. Avoiding and reducing surface soil compaction fosters healthier root development and improves water infiltration rates.
Always maintain soil fertility and pH levels.
Thank you for trusting Beck’s with your seed business. We look forward to helping you any way we can with field scouting, crop diagnostics, and product evaluation. Please feel free to contact myself or your seed advisor to discuss SDS risk management strategies.
FARMserver™ and Escalate™ are trademarks of Beck’s Superior Hybrids, Inc. ILeVO® is a registered trademark of Bayer.
Author: David Hughes
Categories: Agronomy, Missouri
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