Typical symptoms of northern corn leaf blight are canoe-shaped lesions 1 inch to 6 inches long. The lesions are initially bordered by gray-green margins. They eventually turn tan colored and may contain dark areas of fungal sporulation. The length or size of lesions may vary with in different corn hybrids reactions with different resistance genes. Lesions begin on the lower leaves and then spread to upper leaves. Severe symptoms can progress rapidly, resulting in blighted leaves. The disease can be confused with symptoms of Goss\'s leaf blight on some hybrids, and perhaps with Stewarts wilt where this disease occurs.