According to the Guidelines, what is a viability assay survey and what is a bioassay?
A viability assay survey is undertaken using soil samples from fields where PCN is apparently no longer alive and is an indication that the content of the cysts is dead. The viability status of the eggs within the cysts is determined either through a visual assessment of viability by trained nematologists or through the use of viability staining. The PCN Guidelines permit the use of Medola’s Blue Stain or Iodine for differentiation between viable and non-viable PCN eggs. Determining the viability of the eggs is important as cysts with viable eggs may persist in the soil for approximately 30 years. A bioassay is another method to assess and provide confidence that the content of any remaining cysts is dead, no longer able to cause an infestation. It is usually conducted under a controlled environment to maximize any possible multiplication of PCN and to contain any infestation.
