Press Release from the OSU Extension: Hardin County – As of a week ago, most of the corn across the state of Ohio was between the late-R1 (silking) and late-R3 (milk) growth stages, with a few late-planted fields at late vegetative stages. Concerns about tar spot, but more likely, a sense of security provided by relatively high grain prices have led to several fields being sprayed with a fungicide at or shortly after R1 and questions being asked about spraying additional fields that are now at mid reproductive stages (between late-R2 [kernel blister] and R3 [milk]) of development. Concerns about tar spot are understandable, given how widespread the disease was last year (2021) and the level of damage it is capable of causing. However, the basic approach for tar spot management in Ohio should be no different from the approach commonly recommended for managing other, more common foliar, fungal diseases such as gray leaf spot. You have to scout fields, monitor the weather, and if needed, apply the fungicide when it is most likely to be effective, without violating label restrictions.

A tanker truck rolls over and spills tar into a ditch that separates U.S. 30 and I-75.