（1）Protective effect Use of medicine before the plants are not affected, the eradication of bacteria or set up a chemical barrier between pathogen and plant body, preventing the bacteria invasion, in order to enable the plant protection.

（2）Therapeutic effect In or after the onset of parasitic plants, the relationship between the use of fungicides remove bacteria and host or prevent disease development, enable the plant to recover.

（3）Induced resistance effect Also known as immune function, namely through chemical application and make the plant systemic acquired resistance, enhanced the invasion of pathogen resistance.