By Talon Mues and Saleh Taghvaeian et.al
Tar spot was confirmed in V6-V9 corn in several Nebraska counties (and other states) throughout the week of June 15, 2025. It may seem early for tar spot development, but early season development has been common in other states where the fungus has existed for a few years. Scouting efforts should be intensified in fields with a history of the disease or at higher risk, such as pivot-irrigated corn.
Figure 1. Reported tar spot distribution. Gold counties indicate counties where at least one sample was confirmed with tar spot. Gray counties indicate where tar spot was confirmed during the previous year(s). (This image was generated on June 20; please see the Crop Protection Network's map for live updates on tar spot distribution in the Midwest.)
Fungicide applications are not recommended at this time for tar spot management. Multi-state fungicide research (led by Purdue University) results show that applications made for tar spot management are most effective and economical when made between R2-R3, even when disease developed during early vegetative stages.
Source : unl.edu