Corn close up

Editor’s note: The following was written by Nathan Kleczewski, University of Illinois Extension field crop pathologist, for the university’s crop development Bulletin website Oct. 30.


It happens every year. A field is about to be harvested and something is awry. Perhaps the plants are lodged, ears are poorly filled, or pods shrunken. What happened to my crop?

From a plant disease perspective, it is nearly impossible to provide any useful information to the producer.

Many pathogens that can cause crop diseases utilize dead or dying plant tissues for nourishment. As a result, it is common to observe senesced plants in fields with multiple “pathogenic” organisms present in or on tissues.

For example, I recently read a report from the diagnostic clinic where four pathogenic organisms were detected in soybean stems. Was it organism 1,2,3, or 4 that caused the disease? All of them? Was it something else that killed the plant and all four moved in afterwards?

Therein lies the problem — when plants are dead there is no way to know what killed them. The most important thing to properly manage a disease is confident ID of the pathogen.

This is why it is so important to be checking fields throughout the season. Assessing the health of the crop while most plants are still green allows you to understand if the issue is related to environment, disease, insects or some other factor.

During the season, make a point to assess your fields at least four to five times, from planting through maturity. By doing this, you arm yourself with the information you will need to defend yourself from potential yield-limiting diseases in subsequent years.

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