Developing an Integrated Management Plan for Soybean Sudden Death Syndrome (SDS)
by Daren Mueller, Soybean Plant Pathologist, Iowa State University
Sudden death syndrome (SDS) is one of the most recognizable diseases in the North Central soybean-producing areas. SDS is a soil-borne fungal disease with two phases — a root rot phase and a leaf scorch phase.
The foundation of SDS management is to plant SDS-resistant soybean varieties. However, in years when environmental conditions are very conducive for SDS development, host resistance alone may not provide adequate control. With funding from the North Central Soybean Research Program, we investigated management options that could help resistant cultivars be as effective as possible, even in very conducive years.
In a series of studies conducted by 14 soybean breeders and plant pathologists in five participating states (IA, IL, MN, MI, IN) and Ontario, Canada, we did the following: (1) compared the strengths and weakness of six molecular assays to detect the SDS pathogen, Fusarium virguliforme
in roots and soil; (2) evaluated different fungicide products and application methods to see if any would complement cultivar resistance; (3) studied the effect of planting date on foliar symptoms of SDS, and (4) determined if nematode reproduction on SCN-resistant cultivars should be considered in SDS management decisions.
Here is an update on our major findings:
- We identified an effective assay for Fusarium virguliforme, which will provide better diagnosis and quantification of the SDS pathogen from soil and soybean roots.
- We found that ILeVO® fungicide applied as a seed treatment or in-furrow was effective at reducing SDS severity levels compared to control plots. ILeVO® seed treatment reduced disease severity and increased yield in nearly all plantings and cultivars up to 21% compared to untreated plots.
- Foliar applications of any chemicals, including the active ingredient in ILeVO®, had no effect on SDS development.
- We found that foliar damage can occur when ILeVO® and preemergence herbicides are used together, however we found no interaction between the two and no negative effect on plant stand or soybean yield from phytotoxicity caused by ILeVO® or by preemergence herbicides in a two-year study.
- The effect of planting date on foliar SDS symptoms was inconclusive; however, root rot severity was less in later plantings and so was yield.
Several new print and online materials about SDS were developed as
part of this project that farmers can use to refine their IPM strategy
for SDS, including a 10-page, comprehensive, full-color guide, Sudden Death Syndrome
. Download this high-resolution publication for free, or read online.
Read also Scouting Sudden Death Syndrome
and Using ILeVo with preemergence herbicides
. View the video Scouting for Sudden Death Syndrome
on YouTube and the webinar Soybean Sudden Death Syndrome Management Update
, hosted by the Plant Management Network.