Early Season Systemic Wilt

• Occur soon after plant emergence
• Yellowed or bleached leaf streaks (photo above)
• Internal vascular discoloration, crown decay, rot (photo below)
• This phase of disease may result in plant death

Later Season Foliar Blight (photos below)

• After tasseling
• Fully developed typical elongated lesions
• Lesions are long, narrow and have a wavy margin
• Yellowish border may be present
• Note blackish appearance of lesions (saprophytic fungal spore production)
• This disease phase rarely results in plant death, but may predispose for stalk rots

Disease is Vectored by Corn Flea Beetles:

• Bacteria overwinter in insect gut
• Beetles feed on plants in spring
• Insect "etches" leaves (whitish areas in photo below)

Two Phases of Disease:

• Early season systemic wilt
• Later season foliar blight

Yield loss from this disease may occur for a number of reasons:

• Early season systemic wilt reduces stands and weakens plants
• Foliar symptoms reduce functional leaf area, reducing photosynthesis and sugar production
• Stalk rot potential is increased
  • When demand for sugars to fill the ear exceeds supply from damaged leaves, the plant takes available sugars from stalks instead, increasing stalk rot potential

Plant Resistant Hybrids

• Pioneer rates its hybrids for resistance
• Contact your local Pioneer sales professional

Control Flea Beetles

• Systemic insecticide seed treatments help to reduce flea beetle populations
• Foliar insecticides may be needed in some cases
  • Scout for flea beetles and apply insecticides if insect populations exceed thresholds established by your state
• Predict flea beetle / Stewart's wilt occurrence
  • Sum the mean temperature for the months of December, January and February
  • Risk increases with the sum of mean temperature - See extension materials from your state