Sweet potatoes could one day become a niche crop in parts of the Pacific Northwest, a Washington State University researcher says.

Tim Waters, regional vegetable specialist for Washington State University Extension in Franklin County, conducted research into sweet potatoes as a possible crop in the region for several processing companies, which he cannot disclose.

Potato processors in the Columbia Basin hoped to bring more sweet potato production into the region to save on shipping costs.

Waters tested varieties and irrigation needs.

“It’s a crop that requires warm soil temperatures,” he said. “Warmer micro-climates in the Columbia Basin would be better suited.”

Sandy soils serve sweet potatoes best because they heat up sooner and have good drainage, Waters said.

A cool growing season hinders the crop. Soil temperature and moisture are critical for the first 30 days in the ground. If the soil temperature isn’t warm, a sweet potato cutting won’t start to grow the proper kind of root, Waters said.

“If you don’t have those conditions, you’re just going to get these big, above-ground, beautiful plants with nothing below them that you can harvest,” he said.

Sweet potatoes are a different family and species from the Irish potato. Some equipment is similar, but sweet potatoes seed pieces require more care and hand labor when planting and more heat for storage, Waters said.

Waters is interested in pursuing research further if funding becomes available.

“We’ve been learning what not to do, which is almost as important as learning what to do sometimes,” he said.

Growers in California and Louisiana sort the best sweet potatoes for the fresh market. The ones that aren’t near-perfect shapes and sizes are processed, bringing a lower price.

“In order for a grower around here to make good money, they would have to have access to both types of markets,” Waters said, noting processors would have to find a way to select for fresh markets.

Waters believes sweet potatoes could be a small-scale niche crop for the region, with its access to processing and transportation infrastructure and export markets.

Plants that can process potatoes could process sweet potatoes with some modifications, he said. Storage for sweet potatoes would be needed.

Sweet potatoes are grown on relatively few acres, so few herbicides are labeled for their use, Waters said.

He advises growers to try any new crop on a small scale and have a sure market.

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