Bryan Jensen, Dept. of Entomology and Integrated Pest Management Program
In the next few weeks, many agronomists will be spending time in corn fields assessing corn stands. Insects are just one of those factors that can reduce emergence and/or injure plants. I could give you a written description of each insect, but I am not sure you would want to spend that much time reading! I have included a chart which, hopefully, can help troubleshoot insect injury.
Nothing can take the place of finding the actual insect but unfortunately that is not always possible. Instead, we usually must focus on injury symptoms. In the absence of finding the insect this chart should help you contrast and compare insect damage in seedling corn. Keep in mind that each species can have multiple symptoms. What I have listed are classic symptoms. Also, consider that you may be in a field with multiple insect species present.
To conclude, let me explain the bottom row titled “how is the damaged distributed in the field”. I have listed the “typical distribution” that we might expect to find. That can easily be altered based on current field conditions and/or cropping history. For example, an insect that is typically randomly distributed may be clumped if there is a manure application, wet area, or something similar that will concentrate damage in one area.
As always, when troubleshooting insect damage walk a representative part of the field, stay unbiased and look at several plants before reaching a diagnosis.