At least 400 randomly selected tubers from each qualifying seed potato lot are collected and sent for post-harvest testing.
The main emphasis of the post-harvest test is the detection of viral infections which may have occurred during the previous growing season through transmission by insects or farm machinery. When infections of this type occur the plants may remain symptomless; however, pathogens can be carried over in the seed tuber to the next season. The post-harvest test attempts to identify where and to what extent these infections have occurred.
The main diseases for which readings are taken include:
- C Potato Leafroll Virus;
- C Mosaic Virus;
Test results may be obtained from individual growers.