Potato virus Y

Mark Pavek, potato specialist at Washington State University, talks about the ways even a small potato virus Y infection can affect grower costs Jan. 23 during the Washington-Oregon Potato Conference in Kennewick, Wash.

KENNEWICK, Wash. — Even a little bit of potato virus Y can cost growers a lot of money, a potato expert says.

Some farmers may view low infection rates of the virus as “inconsequential,” but Mark Pavek, a Washington State University professor and potato specialist, said he wanted to determine how much they could cost growers.

Pavek spoke during the Washington-Oregon Potato Conference last week in Kennewick, Wash.

More than half of the commercial seed lots tested in 2018 by WSU had at least 1% of the plants displaying symptoms of potato virus Y, Pavek said.

Pavek said the virus can drop the price from 26 cents per healthy plant to as low as 5 cents per plant, depending on the virus strain.

The original strain of the virus has the biggest impact, a loss of up to 55%, Pavek said. Other strains are not as severe but still significant, he said.

A 1% infection can cost a grower as much as $42 per acre.

A 2% infection can cost $84 per acre.

A 5% infection can cost a grower $210 per acre.

Neighboring healthy plants can compensate for up to 56% of the plants infected by the virus, Pavek said.

Pavek recommended farmers ask for a seed health certificate to determine the level of disease found in a seed lot. Certified seed doesn’t guarantee disease-free seed, he said.

Occasionally, a seed lot will have close to 100% PVY, Pavek said.

Some growers may take that seed because a particular variety is in short supply or they need it to fulfill a contract, but Pavek said they should calculate their costs.

In the long run, finding varieties resistant to the virus is likely the best option, Pavek said.

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