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Applied Research Report: Crop Disease and Insect Management in Northwest Illinois

The 2018 and 2019 growing seasons have been a challenge for our producers in northern Illinois to say the least. Cold, wet springs prevented us from getting the crop in the ground, and extensive late-season rainfall delayed us in getting it out. As a result of these abnormal growing conditions, a wide array of issues have popped up to cause problems for producers. Producers had to deal with nutrient deficiencies as well as a variety insect pests and disease issues in both corn and soybean. In response to production issues such as this, researchers from the University of Illinois have published the “2019 Applied Research Results: Field Crop Disease and Insect Management,” which is currently available online here:

The report serves as a one-stop shop for relevant applied research and includes evaluations of plant varieties, management practices, and insecticide/fungicide applications on corn and soybean. As Dr. Nathan Kleczewski, Extension Field Crop Pathologist with the University of Illinois says “It’s not just diseases; it’s weather, production, and insects. In the future, we hope it can continue to expand to include other areas and crops.”  Co-author on the report Nick Seiter, Extension Field Crop Entomologist, exhibited similar enthusiasm over the report, “With these field experiments, we continue to monitor trait and insecticide performance for rootworm control every year to document resistance development and provide efficacy comparisons to our clientele. Our hope is that producers will be able to use this guide to inform their decisions on insect control.”

Researchers and producers continue to react to what mother nature throws our way, continually attempting to find cost-effective methods to reduce disease and insect impact. Despite the development of traits and seed treatments to battle these diseases, responses to these products are quite variable. “Having these data published annually and stored for posterity is extremely important. You might forget that a year was particularly wet or dry, and that is why certain diseases were problematic or non-issues,” Kleczewski said.

This report is of interest to growers in Northwest Illinois as it contains results from university experiments which were conducted locally, at Highland Community College’s research farm in Freeport. “Every year has its own set of challenges, but it feels like we have had a little bit of everything the last few years” Commercial Agriculture Educator Phillip Alberti said. Tar spot, for example, exhibited a dramatic increase in incidence and severity across the state in 2018 only to be relatively absent the following year due to dry conditions during the middle of the summer. Tar spot, caused by the fungal pathogen Phyllachora maydis, is an emerging disease in Northern Illinois. Tar spot symptoms are quite distinct, with infection resulting in small, raised, black spots (ranging from circular to oval) on infected host tissue. The dark spots that form are called ascomata, which contain fungal spores that spread through wind storms and rain splash. The spots are surrounded by a tan or brown halo and may appear on both sides of the leaves, leaf sheaths, and husk; these spots can be found on both healthy and dying tissue.

Although diseases in soybeans were not a major issue in 2019, soybean cyst nematode was still present in most fields to some degree according to the first state-wide nematode survey in nearly a decade. Nematodes are microscopic, soil-borne worms which live in the soil and are quietly responsible for yield losses up to 20% in corn and soybeans. Nematodes feed on plant roots using a piercing mouthpart which can also provide a pathway for root pathogens; pythium, rhizoctonia, and phytophthora in soybean, for example. While soybean cyst nematode (SCN) is often the most talked about, corn nematodes are quickly becoming an area of interest. Nematode damage is often overlooked in fields because the damage they cause is easily confused with other stress factors such as drought and nutrient deficiencies.

            “In this year’s soybean nematode survey, we saw that soybean cyst nematode is really starting to adapt to the commonly used PI88788 source of resistance. This means that this nematode is not being controlled as efficiently as it was in the past. This first year of data really shows that producers need to be monitoring their fields for this nematode to ensure that their yields are not being impacted. Often you don’t see the damage caused, and fields suffer ’hidden’ yield losses. Routine sampling and implementation of integrated management practices can help keep this pathogen in check. We will be doing more surveys this spring, as the wet and cold end to the season prevented us from sampling in a significant portion of the state,” Kleczewski says.

Nematodes are found in nearly every field, but often not at damaging levels; these fields may experience yield losses of up to 10 bushels and not even know it. Despite the introduction of control methods, repeated use of resistant varieties and nematicides has led to the development of tolerant nematode populations making treatment options less effective. Nowadays, a single control option such as using resistant varieties will not work like it used to; a multifaceted approach which uses crop rotation, resistant varieties, and nematicides may be required to keep populations at a manageable level. There are over 50 known species of nematodes which feed on corn in the U.S., with a wide range of adaptations to soil textures, climatic factors, and production systems. However, not all nematodes are created equal as some can cause significantly more damage than others. It is for this reason that determining the type and number of nematodes present in IL is crucial component in the development of control options.


Kleczewski notes the report also includes information on management practices that didn’t work. “In applied research, the lack of an effect of a management practice is just as important as if a practice has an effect. Why?  Because management costs money and we want our producers to be as profitable as possible. If something doesn’t work, we want that information out there just as much as if something works,” he says. The emergence of new diseases is nothing new, but this has led to many questions about a disease we are unfamiliar with and producers can combat it. “This is where these reports can become extremely valuable at the local level. If I get a call from a producer asking about control options for various diseases, this is where I am going to get my information every year. It is a great resource and I applaud those who have worked so hard to get this information to us.” Alberti said.