Northern corn leaf blight genes identified in new study. Midwestern corn growers know the symptoms of northern corn leaf blight all too well: greenish-gray lesions on the leaves that can add up to major yield losses if not detected and treated early. Corn resistance genes have been identified, but the fungal disease has found ways to sneak around corn's defenses. Now, researchers have discovered how the fungus is outsmarting corn, and they may be able to use this information to help corn fight back. Source 7i.