Potato Field Day 2

Mark Pavek, Washington State University professor and potato specialist, puts up a hand to stop the process as Zach Holden and Vito Cantu drop seed potatoes for planting May 6 at the university’s research unit in Othello, Wash. Pavek and his team compare the samples to the growing conditions farmers see in their fields.

Researchers don’t think wildfire smoke necessarily hurts potato development. But they’re not prepared to say it helps, either.

Last year, potatoes may actually have benefitted as a result of smoke, said Mark Pavek, professor and potato specialist at Washington State University.

“Yields were very high,” Pavek said.

The smoke can act as a shield for solar radiation and reduces temperatures in streams and rivers.

“It’s possible the smoke reduced temperatures to a more comfortable level for the plants,” Pavek said. “Quite often in the Columbia Basin, it’s too hot some of the days during July and August for the potato to maximize its production.”

Potatoes typically prefer temperatures in the 70s and 80s. At 95 degrees Fahrenheit or higher, potatoes shut down to some degree.

If smoke occurs in July and August, Pavek said it might not be possible to drop temperatures low enough.

“One of the biggest factors that reduces our yields in the Columbia Basin is when it gets too dang hot,” he said.

Carrie Wohleb, associate professor and regional extension specialist for WSU in Moses Lake, has observed ozone injury symptoms on plants. Wildfire smoke releases a lot of ozone, a pollutant near the surface level.

Acute symptoms are only likely to occur when fires are close, air temperatures are high and air inversions are keeping the smoke and ozone from dissipating, Wohleb said. Potato plants tend to get a speckling or stippling appearance, or pockmarks.

“The nice thing about potatoes is they seem to grow out of it once the concentrated ozone level depletes,” she said.

The impact on potatoes is minimal, but beans can be completely taken out, Wohleb said.

“Beans are like the canary in the coal mine when it comes to air pollution,” she said. “They tend to start with a bronzing symptom on the leaves that quickly moves to necrosis.”

The smoke scatters sunlight, moderates temperatures and increases dew on the crops, Wohleb said.

Farmers tend to see more diseases driven by cooler, wetter conditions as a result, such as downy mildew on onions and late blight on potatoes, Wohleb said. She recommends farmers scout for the diseases and use protective sprays if needed.

Some growers may think the smoke harms photosynthesis, the where plants transform light energy into chemical energy.

“The degree to which smoke is going to limit our yield probably depends on how much light is being blocked and for how long,” Wohleb said. “I like to tell people that if they have to use their headlights, then I’m pretty sure smoke is impairing photosynthesis.”

Pavek stresses that the benefits seen in last year’s crop are only an example from one year.

“I don’t want to say smoke is a good thing for potato production,” he said.

It would be difficult to replicate smoky conditions for research. It might require setting up an experiment in a greenhouse, Pavek said.

“I don’t think I would do it unless the (Washington Potato Commission) says this is priority number one,” he said.

Chris Voigt, executive director for the commission, said the agency won’t be asking for a smoke study this year.

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