Tar Spot is a newer disease in the United States, only arriving in 2015. “Tar Spot has led to some pretty big yield losses, as much as 50 bushels,” said Andrew Friskop, plant pathologist, NDSU Extension. “We don’t have as much host resistance where most of our management tools are being relied on right now as fungicide applications.” The fungal disease can be difficult to identify. “Your best chance to start looking for it is in any late planted corn or maybe some corn that has really long maturity. As the name describes, you’re looking for black spots. What you’re going to see is maybe one tar spot lesion per every 50-or-100 plants. It’s pretty low as far as frequency, so have some patience.”
