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Northern Corn Leaf Blight


© Purdue University, Plant and Pest Diagnostic Laboratory

Pathogen(s) causing disease:

Exserohilum turcicum (previously called Helmithosporium turcicum)

Location:

Predominantly corn-growing areas with humid climates

Symptoms:

Long cigar-shaped gray-green or tan lesions. As the disease develops, the lesions spread to all leafy structures, including the husks.

Conditions:

 Favored by extended wet, cool, humid weather, minimum tillage, and continuous corn. Usually occurs during or after pollination.

Management:

  • Planting resistant hybrids is the most effective method for control of NCLB. Two types of resistant hybrids are available to growers to control northern corn leaf blight: partial resistant hybrids, which protect against all four of the known races of the fungus and race-specific resistant hybrids, which protect against a specific race. Partial resistant hybrids are the most common, but hybrids with both types of resistance are available. Resistant hybrids should be planted in all commercial dent corn production fields.
  • A one- to two-year rotation away from corn and destruction of old corn residues by tillage may be helpful in controlling the disease if susceptible hybrids must be grown.

Damage:

This disease rarely causes significant yield losses during dry weather, but during wet weather it may result in losses of over 30 per cent if established on the upper leaves of the plant by the silking stage of development. If leaf damage is only moderate or is delayed until 6 weeks after silking, yield losses are minimal. Northern corn leaf blight also predisposes corn to stalk rot by increasing stress on the plants.

Sources:

Purdue University
The Ohio State University

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