Fungicides, also known as fungicides, bactericidal algaecides, microbicides, etc., usually refers to the chemical agents that can effectively control or kill microorganisms in the water system -- bacteria, fungi and algae.
Protective agent, protective agent in the pathogenic microorganisms did not contact the plant or not immersed in the plant body before the treatment of the plant or the surrounding environment, to inhibit the germination of the pathogenic spores or kill the germination of the pathogenic spores, in order to protect the plant from its harm, this action is called protection.
The pathogen has been immersed in the plant, but the plant is showing symptoms in the latent period. Drugs from the plant epidermis into the plant tissue, through transport, diffusion, or produce metabolites to kill or inhibit the pathogen, so that the disease will not be harmed, and restore health. Agents with this therapeutic effect are called therapeutic agents or chemotherapeutic agents.