Home --> Field Crops --> Diseases

Diseases

Diseases that can affect yield and quality of field crops in Illinois are numerous. For plant diseases to develop, certain components of the disease triangle must be present. These components are a susceptible host crop, a plant pathogen able to infect the host crop, and an environment that favors disease development.

In general, plant diseases of field crops in Illinois are caused by biotic pathogens belonging to one of four groups: bacteria, fungi, nematodes, and viruses. Examples of important diseases that cause losses in Illinois field crops can be taken from each of these pathogen groups. Tactics used to manage these pathogens can vary, so it is essential to know the cause of the problem.

Management practices designed to reduce plant diseases affect specific components of the disease triangle. Multiple practices need to be deployed to limit more than a single component, an approach known as integrated disease management. Integrating different management practices often results in better disease reduction and helps reduce selection pressures. Pathogens are affected by selection pressures when certain individual management practices are used (i.e., some host-resistant genes and some fungicides), and this can result in new "races" of the pathogen or fungicide-resistant strains of the pathogen being selected.

The first step in managing a plant disease is to diagnose the problem. Diagnosing a disease from symptoms alone is not always possible, and some pathogens can cause similar symptoms. Misidentification can lead to inappropriate control recommendations (e.g., applying a fungicide to control a bacterial disease), so properly identifying the problem is critical. Magnification with a hand lens or microscope may help in observing spores or fruiting bodies of some plant-pathogen fungi. When diagnosis is not possible with the tools and resources you have available, collect and send affected plant samples to a plant diagnostics lab. The University of Illinois Plant Clinic serves Illinois producers during the growing season.

Copied from Chapter 14 of the Illinois Agronomy Handbook
Carl Bradley, Author


2019 Bulletin: Register now for Tar spot Webinar, March 1
3/1/19 at 9:00 am CST     Join Dr. Nathan Kleczewski from the University of Illinois Extension  for an update on Tar spot in corn. ...

2019 Bulletin: What effect will cold temperatures have on pests and pathogens?
Nathan Kleczewski Research assistant Professor and Extension Field Crop Pathologist Nick Seiter- Research Assistant Professor and Extension Field Crop Entomologist   Many in the Illinois agricultural community are wondering what effects the recent...

2019 Bulletin: Soybean Quality Issues in 2019
I have had several conversations with members of the agricultural community regarding seed quality resulting from issues derived from delayed harvest and persistent wet conditions encountered in many parts of...

2019 Bulletin: New Tar Spot Publication Available
A new publication on Tar spot of corn is available through the Crop Protection Network.  In this publication we have summarized our current knowledge of the disease, it's impacts, as...

2018 Bulletin: PEst and Pathogen Applied Research Guide now available
The 2018 report on applied pest and pathogen research in Illinois is now available.  This guide provides information on pest and disease management research updates.  It is currently located at...