Of all the diseases we face in corn, tar spot is the one I’ve seen brought up most frequently lately, both in publications and in conversations with farmers and other agronomists.
There’s a really good reason for this, as its impact on yields can be immense.
Tar spot is a foliar disease caused by a fungus that produces a toxin that quickly kills leaf tissue and causes plants to cannibalize more nutrients from other plant structures during reproductive stages, making them more vulnerable to other diseases and lodging.