The practice of removing infected plant material, sterilizing tools, and maintaining clean garden conditions to prevent pest and disease spread.
Garden sanitation prevents pest and disease spread. Remove infected leaves immediately and dispose of them (compost if hot enough, or trash). Sterilize pruning tools between cuts (10% bleach dips) to avoid spreading pathogens. Avoid overhead watering that spreads fungal spores. Clean practices prevent problems and reduce need for spraying.
Sanitation is prevention. It stops diseases before they establish, reducing or eliminating need for pesticides.