We first experienced Tar Spot in 2018.   Been a threat every year since.   The more humidity.... the greater the chances of Tar Spot incidence.

From Purdue University:

"Tar spot pressure in corn is fueled by cool (60-70 degrees F), humid conditions (>75% relative humidity) and prolonged leaf wetness (>7 hours). Therefore, tar spot pressure is typically higher in areas such as those closer in proximity to the great lakes (e.g., Northwest Indiana), river bottoms, and irrigated corn acres. Furthermore, it is also important to note that previous research has found that the pathogen that causes tar spot can overwinter on infested corn residue on the soil surface, thus causing crop infection risks in the following year(s)."

Has Tar Spot been found in your area in previous years?  If not... your risk of Tar Spot is still possible, but not as likely if your area has experienced Tar Spot.  


gordon