SYMPTOMS: Leaf blight: lesions varying in size, generally brown and round-shaped with yellowish area surrounding. First appear on leaf tip, moving to midrib, then produce large, dead spots. Stalk rot: Shiny, black streaks and blotches on the lower stalk. Internal stalk tissue can turn dark gray to brown and become shredded.
TIME OF ATTACK: Anytime from seedling emergence to maturity. Leaf symptoms can begin in May; stalk rot symptoms usually appear in late August to mid-September.
CONDITIONS FAVORING: Cool, wet weather.
MANAGEMENT: Tillage, crop rotation, resistant hybrids. Scout and apply fungicide if necessary for foliar stage of disease.
SYMPTOMS: A sudden onset of grayish-green color of the leaves; lower part of the stalk turns from dark green to light tan; the pith inside the stalk becomes soft. When diseased stalks are split, the pith usually has a reddish or pinkish discoloration and shows signs of deterioration. Pink to reddish mold that begins at the tip of the ear and develops toward the base.
TIME OF ATTACK: After silking in cool, wet weather.
CONDITIONS FAVORING: Cool, wet weather after silking; continuous corn; stress due to extreme weather conditions, unbalanced soil fertility and high plant populations.
MANAGEMENT: Tillage, rotation, resistant hybrids.
GOSS’ LEAF BLIGHT/WILT
SYMPTOMS: seedling blight causing death of young plants; long, slender lesions with wavy margins extending between veins; dark green to black irregular spots.
TIME OF ATTACK: Any stage with leaves.
CONDITIONS FAVORING: Injury to corn leaves; hail damage; continuous corn.