Corteva Agriscience is unifying its regionally focused seed brands under the Hoegemeyer® brand name. This transition strengthens our position as a reliable seed supplier, supports long-term brand growth and increases operational efficiency to scale and better meet growers’ needs today and in the future. While this is a change for our customers, the benefits they enjoy today working with our regional dealer service model brands will remain the same: access to high-performing genetics through locally proven products, trusted relationships and personalized service. Dairylandseed.com will no longer be available after June 30, 2026. Learn more about Hoegemeyer.

7/2/2025

Tar Spot Tracker

By Dairyland Seed Agronomy Team

Tar Spot, Phyllachora maydis, has been confirmed in the Dairyland Seed footprint. The first case was confirmed on June 11, 2025, in Porter County Indiana. Since then, tar spot has been identified in a total of five counties in Indiana and six counties in Illinois.

We will continue to monitor the spread of infection in our area and use maps like the one attached to keep you up to date on areas where tar spot has been identified. We will include tar spot observations that have been confirmed by lab analysis (Red) as well as observations made by Dairyland Seed agronomists (orange). Samples submitted for lab analysis take time to process, and our hope is that by adding our observations in the map we can execute a more rapid management strategy if tar spot is in your area.

Tar Spot Notes

Disease Triangle- All 3 components (Host, Pathogen, Environment) must be present for infection to occur.
Leaf wetness is key for infection and disease severity, heavy dews, irrigation, heavy rains.
TS is polycyclic, this means that infection will spread rapidly if environment is favorable
Fungicide applications will not cure TS in corn, fungicides only pause infection for as long as the residual activity lasts (typically 2 to 3 weeks)
Timely application is key.

Tar Spot Identification

Small, black, circular, raised lesions called stromata appear on leaves, husks and tassels (circled in red)
Stromata cannot be removed from leaf tissue with water or rubbing
Commonly misdiagnosed with frass (insect poop), rotten or aged pollen, rust pustules.
As disease progresses stromata coalesce and destroy leaf tissue, causing premature death in the corn plant