According to the Crop Protection Network , yield losses due to tar spot can be variable,
depending on the time of disease onset, weather conditions and hybrid susceptibility. In
severe cases, losses of 50 bushels per acre or more have been observed on susceptible
hybrids.
Yield losses are a function of reduced ear weight, poor kernel fill and vivparity (a condition
in which the seed germinates while still on the cob).
Stalk rot and lodging may increase when Tar Spot severity is high. Severe Tar Spot also
reduces silage corn feed quality by reducing moisture, decreasing digestible components
and reducing energy. No associated mycotoxins have been reported for this disease.