The insecticidal or fungicidal toxicity of pesticides is often expressed as the "median lethal dose" (LD50), which is the dose (mg/kg) required to kill half (50%) of a biological population. If the concentration is expressed as dosage, it is called the "median lethal concentration" (LC50). Fungicides are expressed as ED50 or EC50, which is the dose or concentration required to inhibit 50% spore germination.
Spore Germination Assay: Different pesticide solutions are sprayed onto a glass slide or plate. A quantitative spore suspension is added. After contact with the pesticide solution and a certain incubation time, the percentage of spore germination is examined under a microscope.
Inhibition Zone Method: A suspension of pathogenic fungal spores or hyphae is mixed with agar medium. After cooling, sterilized circular filter paper discs (approximately 6 mm in diameter) dipped in different concentrations of pesticide solution are placed on the surface of the medium. After incubation at a constant temperature for a certain time, the growth of the pathogen is inhibited due to the diffusion of the pesticide solution, forming an "inhibition zone." The size of the inhibition zone is measured to compare the toxicity of the fungicide.
Growth rate assay: The drug solution is added to agar medium, and after condensation, bacteria are inoculated. After 24-48 hours, colony growth is observed, the growth rate is calculated, and compared with the growth rate of the control group without the drug.
