Northern Corn Leaf Blight

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Northern corn leaf blight

Northern corn leaf blight (NCLB) can reduce yield by as much as 30% when ear leaf lesions appear prior to tasseling.1 Consequently, onset of this disease requires prompt preventive measures to protect yield. 

  • Common name: Northern corn leaf blight
  • Scientific name:Exserohilum turcicum
  • Symptoms: Elliptical, gray to tan lesions on leaves. Lesions can be anywhere from 1 to 6 inches long. Symptoms tend to start on lower leaves. Under high humidity, spores coating the lesions turn olive-green or black, giving leaves a dark or dirty appearance.
  • Conditions for development: Moderate temperatures from 65 F to 80 F, precipitation and high humidity create the optimum environment for NCLB fungus growth. Infection requires leaf surfaces to be wet for six to 18 hours.

Fast Facts on Northern Corn Leaf Blight    

  • Cornfields in the Midwest are most susceptible to NCLB due to the combination of moist conditions and higher temperatures during the summer months. NCLB spreads quickly, often from south to north, riding hurricane winds to infect new areas, particularly in states such as Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Nebraska, North Dakota, Ohio, South Dakota and Wisconsin.
  • The NCLB fungus survives the winter on infected corn reside at the soil surface. As temperatures rise in spring and early summer, the fungus produces spores on the residue. These spores are wind-blown onto leaves of the new corn crop, initiating a cycle of infection.1
  • Late-planted corn is the most vulnerable to infection, because it can be exposed to the disease before grain fill is complete.
  • Early infection of NCLB can lead to secondary outbreaks, disease spread and further leaf damage, potentially leading to even greater yield losses. Plants are most susceptible to infection post-pollination, but disease can take hold anytime during corn development.
  • According to the University of Illinois, high nitrogen levels in the soil can increase risk of NCLB infection in corn acres.2
  • NCLB leaf lesions diminish the leaf area responsible for photosynthesis. The more lesions on a plant and the earlier the lesions develop in the growing season, the greater the loss of photosynthetic area and subsequent yield loss.1
  • In addition to yield loss due to reduced photosynthetic area, NCLB lesions can contribute to stalk rot development and lodging during the growing season.1  

Control Tips

Choosing the right corn variety and implementing a robust in-season disease management strategy will help minimize NCLB infection rates and lower the risk of outbreaks in subsequent years.

These management practices can help: 

  • Select a resistant hybrid. Different hybrids exhibit varying degrees of moderate resistance to NCLB. Work with your local seed dealer to choose the right variety for your field conditions and growing history.
  • Proactively manage residue. Production practices that encourage residue to decompose will reduce the amount of fungus available to infect the next year’s crop. It is recommended that you implement a one-year rotation away from corn, followed by tillage. However, in fields with a history of NCLB and using no-till or reduced tillage practices, a more extended two-year rotation away from corn may be necessary to decrease disease in subsequent corn crop.
  • Make scouting a top priority. Scout fields around V14, or just prior to tasseling, to assess the level of disease pressure in the field. Start with the lower leaves, as this is where symptoms typically show first.
  • Apply a fungicide preventively or, if necessary, curatively. Pay close attention to weather forecasts that may indicate the potential for disease development and consider applying fungicide to protect against yield loss.1 Corteva Agriscience offers an effective, fast-acting fungicide that can help protect against and mitigate NCLB infection.
    • Aproach® Prima fungicide provides uptake in plants that is nearly twice as fast as competitors, thanks to the active ingredient picoxystrobin. Click here to see how Aproach Prima can help stop the clock on NCLB.

Consult your local Corteva Agriscience representative and check out our Corn & Soybean Disease ID Guide for more-detailed management recommendations for NCLB and other common Midwest crop diseases.  

1Wise, K. Northern Corn Leaf Blight. https://www.extension.purdue.edu/extmedia/bp/bp-84-w.pdf

2 University of Illinois Extension. 1997. Common Leaf Blights and Spots of Corn. http://ipm.illinois.edu/diseases/series200/rpd202

Aproach® Prima is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Always read and follow label directions.