Potato Virus S

the Potato virus S (PVS) wasn’t considered economically important until recently. So much so that I was unable to find any photos that I could use. I expect that will change as this viral disease of one of the world’s most important crops continues to spread. This virus also infects guar, magenta spreen, and quinoa.


First identified in 1950s in the Netherlands, this nearly symptomless condition can cause crop losses of up to 20%. It now occurs everywhere potatoes are grown. The biggest problem, at this point, with potato virus S, is that it readily combines with other potato viruses to create more serious problems.


​So, what can you do about a disease with few or no symptoms? How do you even know it’s there? Let’s see what we can find out.

Distressed potato (pxhere) Public Domain

Potato virus S symptoms

According to the International Committee on Taxonomy of Viruses, potato virus S may cause small, necrotic lesions. Other sources say that you may see some of the same symptoms as in potato virus A, such as mild mottling, open growth, rough leaves, and sunken veins. You may also see bronzing if the infection occurred early enough in the season.


How potato virus S spreads

This virus is spread by aphids, especially green peach aphids (Myzus persicae) and potato aphids (Macrosiphum euphorbiae). It can travel on shoes, clothing, and garden tools. It can also occur on other host plants that may be a little too close to your potato patch.


​Cleveland’s tobacco (Nicotiana clevelandii), white goosefoot (Chenopodium album), and Widow’s tears (Tinantia erecta) can act as hosts for this virus, so you may want to keep them away from your quinoa and potatoes.

Cleveland's tobacco (Anthony Valois, NPS) Public Domain

White goosefoot (Sanja565658) CC BY-SA 3.0

Widow's tears (clpk62) Pixabay

Chemical treatments are ineffective, but horticultural oils may provide some protection. The best way to avoid potato virus S is to invest in clean seed potatoes and sanitize those garden tools regularly.