Thanks for sharing your update. Roughly what part of Ohio are you in? I am Northwest and here are a few photos on how tar spot has progressed for me. I haven't sprayed any fungicide and so far have not found any varieties that are worse than the pictures. The dates the pictures were taken is in the lower left corner on each. The first tar spot lesions were found on August 8th when the corn was in the R3 growth stage. At that time there was only one lesion per leaf and it was only on 5% of the plants. The last picture is from 2 days ago and the corn is now dented. Roughly 70% of the plants have at least one lesion on the ear leaf, and the highest number of lesions I counted was 6 on the same leaf. 

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20240826_141404 (full).jpg (219KB - 32 downloads)

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20240826_141128 (full).jpg (223KB - 31 downloads)

20240824_171505 (full).jpg (235KB - 33 downloads)