Question

why copper sulphate is used as a fungicide?

Answer 1

as it contains sulphate which is a salt and salt acts as a preventive agent to protect or prevent something from bacteria or vrus

Answer 2

Copper sulfate has anti-fungal properties, and is a key ingredient in some commercial fungicides for farm and garden. These fungicides are typically mixed with water and either lime or soda ash, then sprayed onto the plants. The effect of such a copper sulfate fungicide is prevention or reduction of fungal infections that can disease or destroy the plant. If a plant is already affected by fungus, copper sulfate fungicides may be effective in removing the fungus. This use is effective only if the fungicide is applied soon after fungal infection occurs.