Probabilities for M. oryzae Triticum establishment were estimated and spatially explicit cumulative risk maps developed using the formula P. = IBxIH. x OS, where P. was the probability of M. oryzae Triticum establishment in the contiguous United States; IB was the probability of years suitable for inoculum buildup prior to heading, with a w threshold for inoculum buildup prior to heading associated with M. oryzae Triticum establishment; IH, was the probability of years suitable for infection at the heading stage, with an x threshold for infection at the heading stage associated with M. oryzae Triticum establishment; and OS corresponded to the probability of years suitable for M. oryzae Triticum inoculum overwintering based on the number of days below freezing. The equation used to predict wheat blast outbreaks was P = IB.. x IH. x OS, with w and x thresholds associated with wheat blast outbreaks (explained below).