The right time to prepare and combat tar spot in 2023 corn fields is now, as the disease has started to spread rapidly throughout the Midwest. Purdue University field crop extension pathologist Darcy Telenko says they estimated as much as a 50% loss in yields in some fields last year due to this disease.

What makes tar spot so difficult to control? Starting in the leaf, tar spot will shut the plant down entirely in as little as two weeks. Fighting the disease is challenging, as fungicide application requires strategic timing. Applying fungicides at the same time each year may not be the way to go. If corn is beyond R3, Telenko says the application is not recommended.

Read more on identifying and managing tar spot in your fields here.