Sudden Death Sydrome (SDS) is a soybean disease which will cause soybean leaves to turn yellow with the leaf veins remaining green. This disease was found mid-August in area soybean fields. This year, many upland soybean fields are being injured. Flooded river bottom soils also have this disease, but symptoms seem delayed.
Leaves start to yellow between the leaf veins and turn bright yellow and then eventually turn brown. The dead brown tissue between the veins will typically fall out.
The disease is caused by Fusarium, which is a soil-borne fungus that affects the tap root and crown of the soybean plant. The disease will produce a toxin that moves up the plant and kills the leaves. Infection from this disease occurred in spring but symptoms may show early as late July to mid-August typically.
Infection of soybeans typically can occur from germination through the vegetative stages but can occur at any time. Wet weather increases the development of SDS.
Yield loss can occur with this disease occurs during seed fill. Pods and seed may abort. Yield losses vary from year to year.
The combination of seed treatment and resistant variety is the best strategy to reduce yield loss from this disease next growing season. Foliar fungicides are ineffective. The use of a resistant variety with seed treatment will not prevent this disease symptoms but will reduce the yield loss.
For more information, contact Wayne Flanary at 816-279-1691, Field Specialist in Agronomy, University of Missouri Extension.