When scouting, pay special attention to early-planted fields, especially in eastern Iowa, and fields that are flat, fertile, and expected to have high yields. SDS symptoms are fairly easy to identify. Infected plants initially show scattered yellow or white spots on the leaves. The irregular shape of the spots and the green areas around the leaf veins give SDS its characteristic mosaic pattern. Only the mid-vein and major lateral veins remain green.
Symptoms are more pronounced on top leaves.
Eventually, infected leaves drop but the petioles remain on the stems. Close-up photo of a leaflet with interveinal necrosis symptoms. Diseased plants are easily pulled out of the ground because the taproots and lateral roots have deteriorated. The root cortex is light gray-brown and the discoloration may extend up into the stem. If the disease is severe during the early reproductive stage, flower and pod abortion may occur.