As harvest approaches, remember to consider PHI before applying pesticides for late-season pests. The PHI refers to the minimum number of days between a pesticide application and swathing or straight combining of a crop and reflects the time required for pesticides to break down after being applied. PHI values are both crop- and pesticide-specific. Adhering to the PHI is important for a number of health-related reasons and to ensure that crops being sold for export meet pesticide residue limit requirements.
Helpful resources include:
• The Keep It Clean website, with information about keeping crops market-ready, use of acceptable pesticides, and more! July 30, 2025, at 11:00 CDT, there is a free webinar focusing on Pre-Harvest Tips & Tools – link to register!
• Keep It Clean’s “Pre-Harvest Interval Calculator” helps to accurately estimate PHI for a variety of crops
• The Pre-Harvest Glyphosate Stage Guide
• The provincial crop protection guides include the PHI for every pesticide by crop combination. Access the 2025 Crop Protection Guides for Alberta, Saskatchewan, and Manitoba here!
• The Pest Management Regulatory Agency fact sheet, “Understanding Preharvest Intervals for Pesticides”, with a free copy available to download.