The 2025 growing season will be remembered as a "southern rust year" for many corn producers. By mid-summer, orange pustules and rust spores coated upper corn leaves, signaling a major outbreak. Yet agronomists urge caution before letting last season's experience dictate 2026 plans.

Southern rust is not a perennial threat in the Corn Belt. It doesn't overwinter in Midwestern fields. Instead, it arrives annually via windborne asexual spores blown in from southern regions. Once conditions are right-warm temperatures and even minimal evening dew-the disease can escalate rapidly. In just 7 to 10 days, southern rust can go from minor to yield-threatening.

That aggressive growth pattern caught many growers off guard. But experts emphasize that southern rust is still a transient, opportunistic invader, unlike other foliar diseases that build pressure earlier and more reliably. Gray leaf spot and tar spot, for example, both overwinter in corn residue, giving them a head start in most seasons.

Darcy Telenko, Extension plant pathologist at Purdue University, observed that southern rust thrived during 2025's dry weather, while tar spot and gray leaf spot struggled. That advantage, however, was situational. Under typical conditions, these other pathogens present more consistent yield risks.

Boris Camiletti, Extension pathologist at the University of Illinois, warns against overreacting to southern rust's 2025 impact. He recommends monitoring its movement in southern states early in the season and tracking reports through ipmPIPE, an online pest-monitoring tool. Still, he cautions that visible symptoms lag infection, meaning southern rust can outpace reports and scouting efforts.

Even with better monitoring, 2026 management plans should prioritize threats that are likely to return. "There's concern growers may overprepare for southern rust and underprepare for gray leaf spot and tar spot," Camiletti notes. That misallocation could lead to poorly timed or misplaced fungicide applications.

Beck's Practical Farm Research reinforces this point. Their studies show that tasseling-stage fungicide applications yield the best return on investment-a timing window more aligned with controlling gray leaf spot than the late-arriving southern rust.

The takeaway? Stay vigilant, but keep perspective. Southern rust will likely appear again, but for most U.S. growers, it remains an occasional visitor-not a perennial resident. As you plan fungicide applications and disease scouting in 2026, anchor your strategy around the usual suspects that overwinter, persist, and emerge earlier in the season.