Tar Spot Spreads Across Maryland as Corn Season Heats Up

Maryland has confirmed its first cases of tar spot for the 2026 season, with the disease reported in several counties. The initial reports came on August 18 in Harford and Queen Anne's counties, followed by additional reports on August 25 in Baltimore, Carroll, Frederick, and Talbot counties.

The Crop Protection Network provided a timeline of the reporting dates, noting that tar spot is now documented across multiple parts of the state as corn enters late-season development. This is significant for growers because tar spot has become a recurring problem in Maryland, with 13 of the state's 23 counties having reported cases in previous years.

The latest detections add another variable for farmers to consider, particularly given that a significant share of the state's corn crop remains in relatively favorable condition. As of August 30, USDA rated 35% of Maryland corn as good and 21% as excellent, meaning 56% fell within the two highest categories.

While the confirmed cases are primarily an agronomic warning rather than evidence of a statewide production shock, they do demonstrate why tar spot monitoring has become relevant beyond the Mid-Atlantic region. Tar spot has also been reported in 16 other states this season, including major corn-producing states such as Illinois, Indiana, Iowa, and Ohio.