Mini-cereal rust risk update, July 21, 2025

The full weekly Prairie Crop Disease Monitoring Network (PCDMN) Prairie wind trajectory cereal rust risk reports for 2025 are now finished. However, depending on the current situation and any subsequent reports of rust on the Prairies, the PCDMN will issue mini-updates.

Crop development and weather

• Prairie winter wheat crops are generally finishing the grain filling growth stages, while much of the spring wheat crop is moving out of head emergence and flowering and into early grain filling
• For the previous seven day period as of July 20, 2025, many areas of the Prairie region had at least 15-30 mm of rainfall, although some areas (e.g. Calgary region) had over 65 mm of rainfall for the same period (https://www.agr.gc.ca/resources/prod/doc/pfra/maps/nrt/pr_07_ac_s_e.pdf?timestamp=1753132257195)
• The driest areas tended to be in the Peace region, especially the central to north Peace regions, as well as northern cropping areas in Alberta and Saskatchewan. Rainfall levels were lower in most of Manitoba during this period with <5 mm in the Winnipeg and Interlake regions
• The main source of cereal rusts are from the Pacific Northwest (PNW) and the Texas to Nebraska corridor. Starting in early to mid-June winter wheat crops in Texas/Oklahoma region would have been moving into maturity and the start of harvest. In the PNW and Kansas/Nebraska region winter wheat crops would be moving into maturity and very early harvest as of mid-June to late June and into July
• As crops mature they no longer represent a significant source of stripe rust uredospores for the Prairie region
• As of July 20, 2025 harvest is nearing completion in Texas, Oklahoma and Kansas, while in Nebraska, Oregon and Washington State harvest is 47, 36, and 18% complete (Harvest progress as of July 20, 2025)