• Lesions are generally:
  • from 1/8 to 1/4 inch wide by 1/8 to 1 inch long
  • tan in color
  • rectangular to oblong in shape
  • usually found on leaves
  • variable, making identification more difficult than for other diseases
• Lesion type may depend on hybrid genetics
• Lesions usually develop first on lower leaves and work up the plant

Southern Leaf Blight (SLB) may resemble gray leaf spot, but these characteristics differentiate lesions:

• Fungal disease caused by Cochliobolus heterostrophu (also known as Bipolaris maydis)
• Thrives in warm-temperate or subtropical corn-growing environments, including the Southeastern U.S.
• Overwinters primarily in surface debris from the previous corn crop
• Spores are windblown or splashed by water to new crop leaves where they germinate and infect the plant
• Development is favored by warm (70 to 85 F), moist weather and free water on the leaf
• Under ideal conditions, the fungus is able to complete its life cycle in only 60 to 72 hours

• Can cause significant loss of corn leaf area when conditions favor the disease
• Loss of leaf area results in reduced photosynthesis, lowering yield potential and increasing risk of stalk rots
• The earlier the disease begins in the growing season, the greater the potential for yield reduction
• Ear and cob rots may also occur due to this fungus

• Genetic resistance
  • Most effective form of management
  • Pioneer breeders have selected for resistant parent lines and hybrids for over 30 years
  • Hybrid ratings range from "3" to "7" on Pioneer's 1 to 9 scale (9 = resistant)
  • Growers in high-risk areas with a history of SLB occurrence in their fields should choose hybrids with a "6" or "7" rating for SLB resistance
• Crop rotation to reduce corn residue level and help break disease cycle
• Tillage to encourage breakdown of crop residue
• Fungicide application

• Scout corn to detect SLB early
• Monitor disease development, crop growth stage, and weather forecast
• Apply a foliar fungicide if:
  • Disease is spreading rapidly or likely to spread and yield may be affected
  • Disease level exceeds threshold established by your state extension plant pathologist
• Common fungicides include Headline, Quadris, Quilt, PropiMax EC, Stratego and Tilt