Each season, plant diseases may arise that potentially limit crop productivity. There are several useful maps that you can use to help track some of the most mobile diseases, including rusts of wheat, corn, and soybeans. Rusts do not overwinter in Illinois, and consequently blow in from warmer regions each season. If they arrive early enough, prior to critical stages of crop development, significant yield losses can occur; therefore, a timely application of a fungicide may be warranted. However, if they do not arrive, or arrive later in crop development, fungicide applications are not required. Thus, tracking the movement of these diseases can help ensure grower profitability.
In #wheat, we are mostly concerned about stripe rust, but other diseases including stem and leaf rust can occasionally cause issues. In #corn, the major issue is Southern rust. #Soybean rust also should continue to be on our radar, despite it not developing into the widespread issue once predicted.
Other diseases are resident/established, meaning that they overwinter in our region and we see them at some level annually. These include diseases such as grey leaf spot, tar spot, and northern leaf blight in corn, and frogeye leaf spot in soybeans. Tracking these diseases during the season is less useful for management, but may help producers know where more inoculum may be present the following year, resulting in potentially higher disease risk.
We will be monitoring the rusts this season in wheat, corn, and soybean, and monitoring counties where tar spot has not been previously identified. It is more important for us to track the yearly spread of tar spot into new areas as opposed to monitoring areas where it has been found. Remember, once it is found, it is established in that area from that point forward. Not finding tar spot in a county where it was detected in the past does not mean the disease was absent, but more likely means the number of sites / samples were not sufficient to detect it, and that relative levels were low. That being said, we are focusing on areas where this disease has yet to be detected. Starting in May, if the county already has had tar spot reported in the past, it will be shaded in on the map. We will provide commentary here and on the map to let you know if any hot spots develop.
To access real time wheat rust maps during the growing season click here
To access real time corn southern rust maps, click here
To access soybean rust maps, click here