Koch’s Postulates Definition :
Koch’s postulates are the methods of identification of a previously unknown disease. After detection of a pathogen on a diseased plant, the pathogen is identified with the help of authentic manuals.
Robert Koch Postulates :
if the pathogen is known to cause such a disease, then the diagnosis of the disease may be considered completed. If, on the other hand, the pathogen found seems to be the cause of the disease, but no previous reports exist regarding the cause of the disease, then the following steps are taken to verify the Koch’s postulates that the isolated pathogen is the cause of the specific disease.
Koch’s Postulates Steps :
(1) The pathogen must be found associated with the disease in all the diseased plants examined.
(2) The pathogen must be isolated from the diseased plant and grown in pure culture on nutrient media, and its characteristics, appearance, and effects recorded.
(3) The pathogen from pure culture must be inoculated on healthy plants of the same species on which the disease appears, and the pathogen must produce the same disease on the inoculated plants.
(4) The pathogen must be isolated from such diseased plants, grown in pure culture again and its characteristics must be identical like those observed in step 2.
Koch’s four postulates are known as Koch’s rules or postulates. if all such steps are followed and proved true, then the isolated pathogen is identified as the organisms responsible for the disease.
Koch’s postulates are mostly possible with pathogens like bacteria, fungi, parasitic higher plants, nematodes, and some viruses.