Fungicides are biocidal chemical compounds or substances used to kill or prevent the growth of parasitic fungi and their spores. They work in a variety of ways, but most of them damage fungal cell membranes or interfere with energy production within fungal cells.

Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, and profit to farmers.
Fungicides are one control method that can be used in an Integrated Pest Management plan for fungal diseases.
Note that in agricultural crops, fungicides protect yield potential, they do not increase yield and cannot retrieve lost yield if applied after an infection is established.
Before making the decision to apply a fungicide correct disease diagnosis is essential.