A predictive model for ergot ascospores was recently developed for the Lower Columbia Basin of Oregon.
The model uses accumulated degree-days (beginning January 1, with a base temperature of 50°F and upper threshold temperature of 77°F) to forecast when ascospores are likely to be present.
According to the model, most ascospores are produced in the Lower Columbia Basin when accumulated degree-days are between 414 and 727.Accumulated degree-days as of May 10 were 387 in Hermiston, OR (black solid line).
At this time in 2017, accumulated degree-days were 302 (orange dotted line). Based on weather forecasts, the degree-day model will reach 414 over the weekend.
For more details on the model and how it was developed, please see our recent publication in the journal Plant Disease (https://doi.org/10.1094/PDIS-05-16-0609-RE).