Harvest Time Is Not The Time To Determine If A Disease Affected Your Crop
DR. NATHAN KLECZEWSKI
URBANA, ILL.
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 are also excellent saprophytes. That means they utilize dead or dying plant tissues for nourishment. Consequently, when plants prematurely senesce, these organisms see these plants the same way as I viewed Golden Corral in college- it’s chow time! 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 form 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 4 moved in afterwards? Therein lies the problem- when plants are dead there is no way to know what killed it. The most important thing needed to properly manage a disease is a confidant identification 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 4-5 times throughout the season, from planting through maturity. Look for plants that exhibit abnormal growth or symptoms. Send samples to your state diagnostic clinic for assessment. By doing this, you arm yourself with the information you will need to defend yourself from potential yield limiting diseases in subsequent years.
Don’t be that guy. Don’t wait until it is dry. ∆
DR. NATHAN KLECZEWSKI: Extension Plant Pathologist, University of Ilinois