Scout for Corn Diseases

Scout now for corn diseases. Leaf diseases are common now, although stalk diseases such as Anthracnose Stalk Rot can (pictured) can be devastating later in the season. ( Darrell Smith )

If you’re not out in field scouting it’s time to make the trip—you might be able to preserve yield potential if you catch diseases early. Plant pathologists are seeing diseases rear their ugly heads in fields across the Midwest.

The way you scout is important in finding disease symptomology and identifying any underlying causes. Nathan Kleczewski, assistant professor and Research and Extension field crops plant pathologist at the University of Illinois, provides farmers with a few steps for accurately diagnosing issues in fields:

  1. Look for patterns across the field. Since diseases don’t necessarily follow rows, note what reoccurring issue you see in each spot—ponding, on ridges, etc. If you do see rows or strips it’s likely a to be spray issue or something similar, not abiotic issues.
  2. Get not only close-up pictures, but pictures from a distance, too, and note patterns. This helps positively identify the disease more accurately.
  3. Know your field history—what hybrid or variety was planted? What nutrients were used? When and what chemicals were applied? What diseases do you expect to be controlled or suppressed based on this history?
  4. Understand weather’s effect on your risk. If you’re working with an agronomist, make sure they know what conditions your field has undergone recently to accurately identify disease.
  5. Finally, if you just can’t figure out what it is reach out to experts. Local seed or chemistry representatives, university Extension agents and plant diagnostic labs can help you find out what you have to help gain control.

At this point in the season look for diseases such as: common rust, southern rust, northern corn leaf blight, gray leaf spot and bacterial leaf streak. Risk for each of these diseases depends on the disease triangle: weather conditions, host and pathogen’s presence in the field. Certain geographies might not have all of these diseases. If you don’t know what’s common in your area work with a local agronomist.

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