In The News
When the Air Speaks First: What Spornado Tar Spot Air Monitoring Revealed in 2025
Tar spot (Phyllachora maydis) continues to be one of the most closely watched corn diseases
across the U.S. Corn Belt. This season, Spornado samplers detected airborne tar spot spores
as early as early June, providing several weeks of early warning before field symptoms
appeared.
By early to mid-July, reports began confirming the first lesions in multiple states—closely
following the environmental patterns that have defined tar spot outbreaks over the past
several seasons.
A Consistent Seasonal Trend
Across the Midwest, 2025 showed a consistent trend:
- Spores detected in early June under humid, moderate conditions.
- Visible lesions appearing 2–5 weeks later
Even when the regional trend is predictable, the exact timing in your fields can differ. Air
monitoring bridges that gap, showing precisely when spores arrive where you farm so you
can scout, plan, and spray based on what’s happening locally, not just what’s happening
across the region.
What It Means for Growers
Early signals matter. When spores are detected, scouting frequency should increase.
Spornado air monitoring provides a practical head start, often 14–30 days before symptoms
can be seen.
Weather drives pressure. Warm, humid nights and heavy dews are reliable early
indicators. Using weather modelling tools alongside spore data helps target the fields most
at risk.
Time fungicide applications carefully. Research continues to show the best results when
applications are made between VT and R3, when disease risk is confirmed and canopy
protection is most valuable.
The Takeaway
Tar spot has established itself as a recurring challenge across the Corn Belt. In 2025, early
June air detections again proved their value—allowing scouts, agronomists and growers to
stay ahead of symptoms, optimize fungicide timing, and focus resources where they count.
Spornado will continue sharing regional updates as we analyze the data from last season.
Resources
Crop Protection Network’s Tar Spot Resource Hub:
https://cropprotectionnetwork.org/publications/an-overview-of-tar-spot
Spornado Sampler: https://www.spornadosampler.com