Spraying crops is not a decision that farmers make lightly. Economic thresholds are developed to assist you with spraying decisions.
Alberta Agriculture and Rural Development states that you have the legal right to apply pesticides on your property provided that the pesticide application does not contravene any by-laws, regulations, or generally accepted practices. You have the legal responsibility to ensure that any pesticide application performed on your property does not cause harm to adjacent properties or people.
Farmers have the legal right to apply pesticides on their property. Notification is simply a good neighbour policy that helps eliminate potential risks.