Trends in fungicide use and resistance in North America: the case of Canadian wheat production systems

Fungal plant diseases constitute major constraints to crop production affecting an estimated 20% of the world’s potential crop production (Oerke and Dehne, 2004; Savary et al., 2019). One way to combat fungal diseases is the use of fungicides: natural or synthetic compounds that have toxic and inhibiting effects against fungal (and other fungal-like) pathogens. The battle against plant diseases is as old as agriculture itself. Archaeological accounts indicate that humans started agriculture around 10000 years ago (around 8000 BCE) in the Fertile Crescent, with areas such as Mesopotamia (modern Iraq) developing flourishing cereal grain production and storage systems (Paulette, 2016). As crop production increased, so did the emergence of diseases. The Sumerians and Egyptians described grain spoilage and molds, while the Greeks and Romans referred to rust outbreaks as ‘blights’ or ‘blast’ (Zohary and Hopf, 2000; Zadoks, 2013). Protective practices included selecting healthy-looking seeds to sow the next crop. Grains were also left to dry after harvest to prevent mold and spoilage, stored in elevated structures to keep pests and rodents away, while grain was also processed into flour and malt to further preserve food (Zadoks, 2013).