Koch's Postulates

Activation of isolates was successful with almost all isolates so I am now able to move on to carry out Kochs postulates with them. The aim of Koch's postulates is to confirm a diagnosis that a particular suspected organism is causing the observed disease. The steps were first described by Robert Koch in 1882 and later added to by Erwin F Smith in 1905. The steps are as follows:

1. determine the suspected pathogen is consistently associated with the disease
2. isolate the suspected pathogen from the diseased plant and grow it in pure culture on artificial media and describe it.
3. Inoculate the isolated organism onto a healthy plant of the same species to see if it causes the same disease symptoms.
4. Re-culture the pathogen and determine that it is the same as the original isolate.

Steps one and two have already been completed so I am now going to work on steps 3 and 4.

Isolate activation

I am hoping to 'activate' some isolates by inoculating them into rhododendrons and then re-isolating them from the plant after infection has occurred in an attempt to remind the isolates how to be virulent. Some times we have isolates that have been maintained for so long in culture that they start to behave strangely or they stop sporulating for example. This is a technique to re-activate them before using them in experiments.