Multiple lesions from Northern corn leaf blight on a lower leaf in an irrigated corn-after-corn field.
This is Dr. Nathan Mueller, your local agronomist for Nebraska Extension. Northern corn leaf blight severity has been increasing in East Central Nebraska over the past two weeks since I talked about it last on the radio. As a reminder, last year we experienced problems in the area with this fungal leaf disease, only later in the season.
Three things are needed for infection and disease symptoms to appear on your corn:
- Favorable weather conditions
- Presence of the fungus
- And a susceptible hybrid
Cloudy conditions, frequent rainfall, high humidity, and moderate temperatures between 64 and 81 degrees favor the infection and spread of Northern corn leaf blight. Northern corn leaf blight survives in corn residue and does overwinter in eastern Nebraska fields. Therefore continuous corn ground with a history of Northern corn leaf blight are at higher risk for infection. Hybrids do very in their susceptibility to this disease.
Symptoms of the disease develop several days after the infection occurs and appear as small lesions or dead looking tissue on lower and now even upper leaves. The lesions grow to large cigar-shaped areas as the disease progresses. No treatment thresholds have been determined for Northern corn leaf blight, but the development and spread of the disease prior to tasseling could substantially reduce corn yield.
What should you do?
- Consult your seed guide or contact your seed dealer to get the disease rating for all of your hybrids
- Frequently scout fields with hybrids that have poor ratings for Northern corn leaf blight
- In fields affected by Northern corn leaf blight, consider the cost of a fungicide treatment, corn price, yield potential, and severity of the disease prior to fungicide application.
- And remember to remove adjuvants if spraying fungicides before silking.
For more information, call me at 727-2775 or visit our local website at croptechcafe.org. Know your crop, know your tech, know your bottom line. This is Dr. Nathan Mueller, your local agronomist for Nebraska Extension on KTIC radio.
For more information, read the recent CropWatch article: Northern Corn Leaf Blight Continues and Gray Leaf Spot Starts
