This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

Virus monitoring of seed plots to be used for future production of healthy
certified seed potatoes.

Potato virus diseases did not effect humans but could have a significant effect on the yield and quality of potato crops and processed potato products.

These viruses were spread to potato plants via the mother seed tuber, insects (mostly aphids & thrips) and/or mechanically by contact. Infected seed tubers when planted gave rise to infected plants.

The certified seed potato schemes in Australia were all derived from pathogen tested stocks that were tested for all known pathogens (diseases).

As the seed stocks were multiplied in the field over a period of up to five years they were potentially exposed to reinfection with the plant viruses - Potato leaf roll virus (PLRV), Tomato Spotted Wilt Virus (TSWV), Potato Virus Y (PVY), Potato Virus X (PVX) and Potato Virus S (PVS). Each year the crops were inspected in the field and had to meet the specified National Standard before further multiplication or sale as certified seed potatoes. Some virus infections could reach a significant level in one season.

Crop rejections due to virus diseases have had a significant economic effect on some seed growers and their buyers. The shortage of certified seed potatoes to sell to buyers and for buyers to plant to fill their contracts was an important economic problem.

By checking the health status of the seed plots that the growers would use to plant next years crops growers could avoid planting problem lines of seed and replace them with healthy seed.

The survey results demonstrated that the overall health of the seed plots was, with a few exceptions, very good. No PVX was found and low levels of PLRV, TSWV and PVY were present. However there was a need to improve management practices to reduce the amount of PVS in some growers lines. The common strain of PVS was not known to have a significant yield effect and it did not show plant symptoms and therefore its presence was not taken into consideration during certification. ViCSPA also used the survey results to develop future policies for virus monitoring of growers stocks.