This season we have 17 spore traps deployed in grass seed fields, including 6 in central Oregon, 3 in the Grande Ronde Valley, and 8 in the lower Columbia Basin of Washington State.

So far, spores have been detected in central Oregon (Madras area) and the lower Columbia Basin of Washington State (near Pasco).

A predictive model for ergot ascospores was developed for the Lower Columbia Basin of Oregon that 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. Based on this model, the degree-day threshold was reached on May 19, 2023 in Hermiston, OR (accumulated degree days = 428).

In 2022, the degree-day threshold was met on May 27.

Updated spore counts for Central Oregon are shown below:

Stripe rust has also been observed in experimental plots at COAREC, so scouting for this disease is recommended. There are many fungicide options available for stripe rust control – for more information please refer to the Pacific Northwest Plant Disease Management Handbook: