SDS and Root Rot: Understanding the Silent Threat to Your Crop

Friday, August 28, 2015
SDS Symptoms - SDS and Root Rot

The evidence is frightening.  Sudden Death Syndrome (SDS) has evolved from an isolated and virtually unknown issue into a leading disease causing crop loss in U.S. soybean fields.  Over the past 20 years, university researchers have tracked the rise of SDS from relative obscurity to, in 2014, the cause of more than 60 million bushels in lost yield.  Understanding the disease and its progression has never been more important as growers look to protect themselves from this very real and dangerous threat.  


In general, SDS is considered a late-season disease, but research has shown that its yield-robbing potential begins long before any symptoms are obvious.  Therefore, early and active monitoring of your crops is essential to determine the state of your field.  


The Phases of SDS
There are two phases of SDS – a root rot phase and a foliar symptom phase.  While SDS infects the soybean roots soon after emergence, visible symptoms are not typically evident until flowering begins, after which there are no curative treatment options.  The first visible symptoms are mottling or mosaic patterns between the leaf veins, which eventually turn to brown tissue and necrotic lesions.


SDS-Growth on roots - SDS and Root Rot   
Root Rot – Daren Mueller


What makes SDS particularly devastating is that the root rot phase can occur even in the absence of foliar symptoms – and damage can quietly accumulate in a field that appears to be healthy.  According to Jason Bond, Professor of Plant Pathology at Southern Illinois University, the importance of the root rot phase of SDS should not be underestimated.  “Current soybean varieties can reduce foliar symptom expression by limiting the damage to leaves and the colonization of vascular tissue, but they do not address the fundamental root rot infection caused by the SDS pathogen population in the soil.”  He adds, “Experimental studies show that this early disease infection can result in significant yield reduction even when foliar symptoms are not obvious.”


Addressing the Issue
There are few cultural options currently available to help growers cope with the increasing incidence of SDS.  While some soybean varieties are less sensitive to SDS than others, there are no varieties that are considered highly resistant to this disease.  To make matters worse, soybean tolerance to SDS does not protect against the root rot phase of SDS.  Without effective early season treatment, SDS can cause damage to soybeans that will result in significant yield losses at harvest.  Fortunately for growers, a new seed treatment product is available that has been shown to be effective in limiting SDS infection during the root rot phase and significantly reducing yield loss associated with the disease.


Education and awareness are essential to stemming the tide of SDS.  Knowing what to look for, understanding your options and exercising early and informed decision-making can make all the difference in protecting your field from this insidious disease.  To learn more visit




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