Tar Spot has been detected early in Iowa cornfields, raising concerns for farmers as they prepare to implement their crop protection plans. The fungal disease, which can spread rapidly under the right conditions, is showing up weeks ahead of typical timelines in some areas. This early arrival not only prompts a re-evaluation of fungicide strategies but also raises red flags about the potential for other corn disease threats this year. With a long growing season still ahead, vigilance will be key.
AUDIO: Full Interview with FMC’s Todd Cogdill of Dunlap, Iowa:
Todd Cogdill is a Technical Services Manager at FMC in Dunlap, Iowa. He says while it’s disheartening to see Tar Spot show up a week or two earlier than usual, it also underscores just how proactive farmers have been in scouting their fields. With tight profit margins looming over the 2025 season, growers are staying sharp and working to get ahead of anything that could threaten yield. Early detection is a sign that the message is getting through.
Cogdill adds that Tar Spot isn’t the only disease that thrives in the warm, wet conditions seen across parts of Iowa. Its presence can also create an opening for other diseases to take hold, compounding the risk to plant health and yield.
Cogdill stresses that he’s not trying to sound the alarm—early Tar Spot cases aren’t cause for panic just yet. But he says it’s a clear reminder that it’s never too early to be scouting for signs of disease pressure. With the potential for other issues to develop ahead of schedule, staying alert is key. Now is a good time for farmers to connect with their agronomists and discuss how to pivot crop protection plans if needed.
FMC offers a broad suite of crop protection products designed to help farmers stay ahead of disease threats. When it comes to Tar Spot specifically, Cogdill says their Adastrio® fungicide has been delivering strong results in the field.
With Tar Spot showing up early and other disease threats looming, Iowa farmers are wise to stay vigilant and adaptable this season. Early scouting and timely adjustments to crop protection plans can make a significant difference. Talk with your agronomist and your local FMC retailer to find the solutions best suited for your fields.
