Important Functions Of Fungicides

There are two modes of action of fungicides: one is a protective fungicide, and the other is a systemic fungicide. Protective fungicides directly contact the pathogenic bacteria outside or on the surface of the plant, kill or inhibit the pathogenic bacteria, so that they cannot enter the plant, thereby protecting the plant from the harm of the pathogenic bacteria. This type of fungicide is called a protective fungicide, and its function has two aspects: one is to directly kill the pathogenic bacteria after spraying the agent, that is, "contact bactericidal effect"; the other is to spray the agent on the surface of the plant In the past, when the pathogenic bacteria colony on the plant body was poisoned when it came into contact with the agent, it was called "residual bactericidal effect".
Different fungicides work in different ways. The fungicide applied to the surface of the plant before the pathogen infestation has a preventive and protective effect is called a protective fungicide or a protective agent; the fungicide that can eliminate the infected bacteria at the application site is called an eradicating fungicide; Those that are transmitted to the infected part of the body to eliminate the germs are called systemic fungicides. Many eradicating agents are also systemic agents, and most of them have chemical therapeutic effects. Therefore, in practice, fungicides are often simply divided into two modes of action: protective and systemic. Their mechanism of action can also be roughly divided into two categories:
1. Interfere with the respiratory process of germs and inhibit energy production.
2. Interfering with the biosynthesis of bacterial life substances such as proteins, nucleic acids, sterols, etc. Protective fungicides are mostly products with a broad bactericidal spectrum and low bactericidal power. Systemic fungicides generally have strong bactericidal power and narrow bactericidal spectrum, and some varieties have specific selective toxicity to certain pathogenic bacteria. Because the action point of the systemic agent in the bacteria is relatively single, the bacteria are prone to drug resistance due to genetic mutations. In order to avoid or delay the emergence of drug resistance, the appropriate protective agent and systemic agent can usually be selected for mixed application or alternate use, so that better control effects can be obtained by learning from each other. When using, various pesticide application methods such as seed treatment, foliar spraying and soil treatment should be adopted according to the characteristics of the disease occurrence.