To evaluate the selectivity of some pesticides one has to test the pesticide against the fungal species by Agar diffusion method against purefungal/bacterial culture . If itdevelops the zones of inhibition either of these two ,then it is selective against that species.

There are different tests to evaluate the selectivity of chemicals or biopesticide in vitro. One is the agar diffusion method as already mentioned: the pesticide or the culture filtrate of your putative bacterial or fungal antagonist is placed in a well made into the agar medium. A disk of the fungus to be tested is placed at the opposite site of the plate. a formation of an inhibition area between the well and the fungal colony means that the fungus is sensitive to the tested compound. Another way is to mix the chemical or the culture filtrate of putative antagonists into the melted agar medium and to pour it into the plate. when the agar is solid, place a disk of the fungus to be tested at the center of the plate and incubate. In this case the inhibition activity is measured as the reduction (%) of the growth of the fungal colony in comparison with a control plate (no chemical or culture filtrate)

Hi, You can do that on the petridish by mix the pesticide with the agar media and grow the culture of fungi or bacteria that you want to test.