Tolerance is another characteristic that varies among hybrids. Stromberg and
Donahue (54) observed that even though some hybrids were more prone to blighting
during grainfill, they still yielded relatively more than hybrids that were relatively
more resistant. However, both resistance and tolerance may be overwhelmed by
heavy disease pressure (54). Even when moderately-resistant hybrids are planted
substantial yield losses due to gray leaf spot may still occur (24).