Goss’s bacterial wilt
Gray to light-yellow stripes with wavy margins that follow the leaf veins. Within these lesions, dark green to black, water-soaked spots (freckles) usually appear and are an excellent diagnostic symptom. Systemically infected plants may have orange vascular bundles. Primarily on the high plains of northwestern Kansas, northeastern Colorado and southwestern Nebraska. Resistant hybrids. Crop rotation.
Taken from Corn Production Handbook, KSU Extension
Pest photo source
Diagnosing Corn Problems in Kansas, KSU Extension