USA - Grant protects Florida corn from tar spot outbreak

Tar spot is a rapidly spreading fungal disease caused primarily by Phyllachora maydis, a plant pathogen that infects corn and damages leaves. Tar spot reduces corn grain yield and overall crop quality and could become a severe epidemic on sweet corn. The Foundation for Food & Agriculture Research (FFAR) awarded a $120,509 Rapid Outcomes from Agricultural Research (ROAR) grant to the University of Florida (UF) to address the rapid spread of tar spot in sweet corn. UF provided matching funds for a $241,537 total investment.

Tar spot appears as black, raised spots that form on both sides of the leaves. The spots vary in size and shape and can eventually cause the leaves to yellow and die, significantly reducing crop yield. For over a century, tar spot was restricted to parts of Central and South America, but in recent years the pathogen has made its way to several locations in the United States, including Florida. Despite studies on tar spots on field corn in the Midwest, researchers know little about how to best manage this pathogen in sweet corn hybrids in Florida.

"Tar spot of corn took over 100 years to arrive in the U.S., but only seven years to disseminate to 14 states. Given its rapid spread within the U.S., and in Florida specifically, tar spot has the potential to cause economic losses if the disease is left unchecked. Tar spot has imminent potential to become a severe epidemic, risking over 30,000 acres of sweet corn produced in Florida for fresh market. Therefore, tar spot management strategies directly tailored for sweet corn production in humid Florida conditions are needed to mitigate the lingering risk to the sweet corn industry."

DR. KATIA VIANA XAVIER
Principal Investigator and Assistant Professor in Plant Pathology at University of Florida

"Tar spot disease can have an enormous impact on the U.S. agricultural economy. Given the rapid spread of tar spot within the U.S., it is imperative that we identify ways to eliminate the spread of this disease."
LAKISHA ODOM, PH.D.
Scientific Program Director Soil Health

Led by Dr. Xavier, UF researchers are identifying management strategies by developing an effective chemical control program and analyzing sweet corn hybrids that are resistant to tar spot. The research team is examining the genetic diversity of tar spot samples from Florida and comparing to those from the Midwest. These studies will help researchers gain insights into the pathogen population structure in the U.S. and further delineate tacking points against tar spot. Researchers will then examine epidemiological factors of tar spot development and pathogen survival under Florida conditions.

This research will allow farmers to make more informed decisions about how to sustainably protect crops from corn tar spot and ultimately protect Florida’s corn industry from potentially devastating losses.

FFAR’s ROAR program rapidly funds research and outreach in response to emerging or unanticipated threats to U.S. food supply or agricultural systems. A 2020 FFAR grant funded research at the University of Illinois to develop techniques to study corn tar spot in the Midwest and tools to combat the disease.