Times that are required in running the model.

Here we use Zadoks’ growth scale [47]. The times T1, T2 and T3 are as in [28, 36]. The start time is growth stage 32, corresponding to the emergence of leaf 3 (T1). The final time tend (growth stage 75) is interpolated from the value at growth stage 61 (TGS61 = T3 = 2066 degree-days) and growth stage 87 (TGS87 = 2900 degree-days) from [28, 36]. This assumes that the temperature remains approximately constant in the late stages of the season. We also round the values to the nearest integer. Growth stage 75 was chosen for the end time because it was the time in Dataset D which links yield to disease severity (Table 3). Any host or pathogen growth before tstart can be scaled into the amount of inoculum I0 in the model at tstart; the procedure used to fit the initial inoculum parameter, I0, is reported in S1 Text.