The 2019 growing season in the U.S. was, basically, a continuation of 2018: rain and more rain. Planting was delayed, with many acres going unplanted. The cool and wet growing season also delayed crop maturity.
Mycotoxins seldom occur in isolation. It is not uncommon to find multiple mycotoxins in finished feed and this allows for interactions between them, which leads to synergistic or additive effects in the ruminant animal.