This result has been confirmed by work in Indiana and Missouri and is now generally accepted. Although FS-A is the primary organism associated with SDS, other pathogens may also be involved in disease development. The most studied of these is the soybean cyst nematode. This finding is important, since the disease's timing and severity, relative to soybean development, determines how much yields are reduced. Symptoms Foliar Symptoms first appear as random, irregularly-shaped yellow blotches of various sizes.
Blotches occur between the veins of leaflets and can start at any level in the canopy of plants.
As the disease progresses, blotches run together and begin to turn brown. At first this effect is most pronounced in the tops of plants. At this stage the disease becomes recognizable from the road. With time, you see large dead areas between the veins with the veins remaining green. Affected leaflets eventually die and either stay on the plant or fall to the ground.