Soybeans were scouted at the R5 growth stage and a bronzing purple color was observed. These were soybeans in research plots planted from March to May.
This issue was confirmed by an NC State Extension Specialist as Cercospora Leaf Blight. Although this disease is common in soybean, it rarely causes significant yield losses for North Carolina producers. Symptomology associated with cercospora leaf blight includes yellowing leaf discoloration with a purple or bronze tint, and as the disease progresses, small dark spots along major leaf veins. Management practices include cultural like crop rotations with non-host crops and chemical with the use of fungicides.