Most farmers had a good corn harvest but corn tar spot (Phyllachora maydis) was an issue. Tar spot is a corn disease that came from Central America and seems to be spreading by wind into corn growing states. Tar spot is a fungus that grows rapidly when temperatures are 60-700F and humidity is 75% or higher with rainy, foggy, cloudy summer weather spreading this disease. Corn will mature early with reduced ear weight, poor kernel fill, stalk rot, and possibly lodging with yield losses ranging from 0-60 bushel per acre, depending upon disease severity. Unfortunately, not much is known about this disease.  There are several ways to combat tar spot. No corn hybrid is totally resistant but some varieties (especially early maturing) are more tolerant than others. Fungicides may help but time of application is critical for optimal success. The tar spot inoculum can survive the winter, so getting corn leaves to decompose quickly helps reduce the spread. Crop rotation helps but it appears t...