TWO FORMS: leaf blight and stalk rot.

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.

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.

MANAGEMENT: Rotation, conservation tillage, resistant hybrids.

SYMPTOMS: Small, linear, rectangular-shaped lesions, tan to gray in color. Lesions begin on lower leaves and spread upward.

TIME OF ATTACK: Lesions generally appear near first tassel; disease spread continues through maturity.

CONDITIONS FAVORING: Cloudy days with humid or wet conditions; heavy dew, fog or light rain. Continuous corn and reduced tillage also favor this disease.

MANAGEMENT: Resistant hybrids, tillage, crop rotation, scouting and fungicide application if necessary

SYMPTOMS: Elliptical brown to grayish to tan lesions from 1 to 6 in. long. If humid, lesions may have gray-green centers due to spores on dead tissue.

TIME OF ATTACK: As early as silking, but more prevalent during later development stages.

CONDITIONS FAVORING: Wet, humid weather; heavy dew and fog. Can also have higher rate in continuous corn and reduced tillage.

MANAGEMENT: Resistant hybrids, tillage, crop rotation.

SYMPTOMS: Light cinnamon brown to orange uredia densely scattered on upper leaf surface (more orange than common rust). Black telia form in circles around uredia when leaves start to die.

TIME OF ATTACK: When warm, humid conditions are present.

CONDITIONS FAVORING: Warm, humid weather.

MANAGEMENT: Foliar fungicides at proper timing if cost will be economic.