Potato Virus S

Potato virus S (PVS) wasn’t considered economically significant until recently. This virus also infects guar, magenta spreen, and quinoa.

First identified in the 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 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.

Potato virus S symptoms

According to the International Committee on Taxonomy of Viruses, potato virus S may cause small, necrotic lesions. Other sources say 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 in the season.

Distressed potato (pxhere) Public Domain

How potato virus S spreads

Aphids, especially green peach aphids (Myzus persicae) and potato aphids (Macrosiphum euphorbiae), carry potato virus S. It can also travel on shoes, clothing, and garden tools. 

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.