LEXINGTON, Ky. – A fungus called Fusarium graminearum (FG) is the subject of a multi-institutional and international research collaboration led by the University of Kentucky. The project’s primary aim is to develop our understanding of how the fungus impacts corn and to create new tools and resources for its management.

Many farmers will recall the wheat scab epidemics in the 1990s. Fusarium head blight (FHB) caused by FG impacted wheat crops in the northern Great Plains and the Midwest, resulting in $7.67 billion in direct and secondary economic losses from 1993 to 2001. The US Wheat and Barley Scab Initiative was established in 1997, a national, multi-institutional consortium dedicated to researching the FHB disease to control its agricultural impact. Economic losses from FHB have been reduced over the years as tools for management have improved. However, FHB remains a significant problem if the climate is favorable for infection and disease development.

Lisa Vaillancourt, professor in the Department of Plant Pathology at UK, said that the research focus on FHB over the past two decades has resulted in a variety of successes for cereal crops, like more effective fungicides and improved varieties of wheat and barley, and tools for disease forecasting and risk assessments for producers.

“But in contrast to FHB, there’s been comparatively little attention paid to Gibberella ear rot of corn, which is caused by the same pathogen,” she said.

The calling card of Giberella ear rot (GER) is a pinkish mold that mostly appears on the tip of the ear or sometimes develops from the base and is most easily detected right before harvest. The disease is more difficult to detect after the grain has been shelled. The disease is not new, but it has become an increasing threat throughout the corn belt, with states like Iowa, Indiana, Illinois, and Ohio reporting more cases in recent years. While there are likely many causes for this increase in disease occurrence, Vaillancourt noted that tillage patterns and changing weather may contribute, with FG favored by high moisture levels and cooler temperatures during and after silking.

It’s estimated that over the past five years, GER has reduced yields by more than 278 million bushels in the United States. The disease can cause poor grain fill, reduced kernel size, and increased ear drop. Importantly, FG produces mycotoxins, toxic substances that cause adverse health effects in humans and livestock. High levels of mycotoxins, including vomitoxin, can make grain unsafe for consumption and cause severe digestive issues.

Vaillancourt said that studies demonstrate that FG moves from corn to wheat and vice versa.

“If you only look at the pathogen on one of the crops and not the other, you’re missing part of the opportunity to reduce that pathogen overall,” she said.

UK, in collaboration with Kansas State University, Virginia Tech, and the Federal University of Viçosa in Brazil, was awarded a $686,010 grant by the USDA-National Institute of Food and Agriculture to undertake the study of FG, with a particular interest in understanding how it impacts corn.

Vaillancourt, the project’s primary investigator, said that one of the first objectives is understanding how the fungus adapts to survive and thrive on corn versus wheat. By comparing the genomes of fungus populations isolated from corn with those from strains isolated from wheat plants, researchers hope to find genes or regions of the genome that make it easier for the fungus to thrive on one crop versus the other. Additionally, researchers will study how the pathogen evolves under continuous and rotational cropping conditions and whether the same genetic factors influence FG’s virulence to both wheat and corn.

The collaboration with Brazil will bring unique insights. Vaillancourt explained that in Brazil and other parts of the world, several types of fungi, in addition to FG, can cause GER, representing a more diverse pathogen population. Access to a more varied population means researchers can study more genes and genetic traits contributing to the development of GER compared with FHB. Additionally, corn can be grown year-round in Brazil, allowing a larger number of experiments to be performed there during the study period.

The goal of the four-year project is to identify genetic markers that can detect high-risk FG strains that would lead to the development of improved prediction tools for farmers.

“In successfully completing our project, we hope to incorporate new knowledge into risk assessment models to predict levels of disease and mycotoxins and help growers make informed management decisions,” Vaillancourt said.

Currently, none of the management tools available for GER completely prevent the disease. The FG pathogen overwinters on corn and wheat debris, so implementing deep tillage to bury crop residue can reduce the amount of fungal inoculum in the field. Rotating wheat and corn crops with non-hosts is also recommended to reduce the amount of fungus in the soil. Other management practices include minimizing insect damage to reduce entry points for the fungus and applying fungicides. Vaillancourt added that while these methods are effective, they’re not foolproof, emphasizing the need for better risk assessment and prediction. With tools that can better predict disease based on risk related to host susceptibility, pathogen virulence, and suitability of the environment, farmers will be better able to make timely decisions about spraying or early harvesting if they are in high-risk areas.