Frogeye Leaf Spot

scouted July 4, 2024

Soybeans were scouted at the R4 growth stage and small, circular lesions were observed on leaves.
This issue was confirmed by the NC State Plant, Disease and Insect Clinic to be injury from Frogeye Leaf Spot (FLS) caused by Cercospora sojina. Symptomology associated with FLS includes small, dark, water soaked, circular to angular lesions. As lesions expand they become brown/gray in color with a yellow halo around leaf spots. Frogeye leaf spot favors warm, humid conditions. In this environment, temperatures have been in the high 80's to mid 90's. With adequate rainfall over the past week and a half. These conditions could have synergized symptomology. FLS is best managed using integrated strategies including crop rotations with non-host crops, planting a resistant variety, and in severe cases a fungicide could protect yield. Fungicide applications are most effective when applied between the R3 and R5 growth stages for FLS.

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