Fungicides are chemical substances used to control and prevent the growth of fungi on plants, crops, and other surfaces. They are specifically designed to target and prevent the spread of fungal diseases that can damage plants and reduce crop yields. Fungicides work by either inhibiting the growth and reproduction of fungi or by killing existing fungal spores and mycelium. They are commonly used in agriculture, horticulture, and forestry to protect plants from diseases such as powdery mildew, rust, and blight. Fungicides come in various forms, including sprays, powders, and granules, and are typically applied to plants at specific times during their growth cycle to effectively control fungal infections.