Anyone born before 1960 likely knows what they were doing when Neil Armstrong stepped onto the moon. His words, “One small step for man, one giant leap for mankind,” still echo across the universe. If you grow corn, someday you might remember when you first read about the news you are about to learn. In the fight against tar spot, it could prove to be a turning point in the journey toward improved genetic tolerance and better management strategies.

Recently, Bayer Crop Science announced that its researchers artificially inoculated tar spot in field test plots. Until now, no one had accomplished that feat. Why does it matter?

“By creating field conditions for tar spot to take place, as well as inoculating the field artificially, we now have a reliable opportunity to study the environment and genetic response to the presence of the disease,” says Christian Heredia, Bayer Crop Science market development manager. “We can rapidly identify and promote new corn hybrids with enhanced tar spot tolerance, as well as enable breeding strategies to deliver more genetic potential.”

Big step forward

University researchers across the U.S. in Nebraska, Wisconsin, Minnesota, Indiana and elsewhere have worked diligently to learn more about tar spot since it appeared in the U.S. less than a decade ago. Tar spot, caused by the fungus Phyllachora maydis, was confirmed in 2015 in seven counties in northwest Indiana and 10 counties in north-central Illinois. Since then, it has spread in all directions from those initial discovery points. In years when weather conditions favor tar spot, it can easily knock off a sizable percentage of potential yield.

One roadblock hampering researchers until now was the inability to inoculate corn in test plots like pathologists do for most other economically important corn diseases. Bayer researchers previously replicated tar spot in greenhouses, but that doesn’t always correlate to how a plant will respond in the field, Heredia notes.

Jim Donnelly, a Dekalb technical agronomist, adds, “Our field testing allows us to inoculate tar spot wherever we place our plots to help us study and learn more about this potentially devastating disease.”

DISEASE FIGHTERS: The breakthrough these researchers helped discover should speed up development of hybrids with improved tar spot tolerance. Pictured are Bayer market development manager Christian Heredia (left) and Dekalb technical agronomist Jim Donnelly.

Tar spot management plan

Hybrids with more tolerance to tar spot will be key to managing this disease in the future. But improved hybrid tolerance alone isn’t the answer, researchers say. “Bayer is committed to delivering solutions when it comes to managing and controlling tar spot, both through continued genetic gains and innovations in our fungicide portfolio, to make sure we’re offering farmers multiple options for controlling diseases,” Donnelly says.

Donnelly and Cody Hornaday, Channel technical agronomist, emphasize that a holistic plan — which includes product selection and placement, scouting, applying fungicides when needed and using general disease management best practices — is necessary to manage tar spot successfully.

Bayer’s fungicide portfolio includes Delaro Complete, which offers three modes of action for providing consistent control of major corn and soybean diseases, including tar spot.

Information supplied by Bayer contributed to this story.