Map of the Week – Herbicide carryover risk

The map below shows herbicide carryover risk in Saskatchewan based on summer 2017 precipitation. In-season moisture from last season is the measure that influences herbicide breakdown. Fall rains come too late as the amount of breakdown has already been set. Spring moisture from snow-melt may liberate herbicides from the solid portion of soils, but at that time the soils are too cold and microbial populations too low from winter to result in any substantive breakdown. Many areas have been dry since then.

Click here for a larger version of the map.

Farmers in other provinces can look at the rainfall amounts (<75mm) in the high-risk areas on this map to extrapolate risk for their farms. This article has more information plus a Manitoba risk map.