Sweet potatoes showing promise

HERMISTON, Ore. – Sweet potatoes might prove to be a sweet crop for Columbia Basin growers.

The crop did surprisingly well in 2011 and 2012 trials near Pasco, producing yields comparable to those in Louisiana and California, the top sweet potato-producing states.

“After plants got established and started growing, they really grew fast,” Washington State University Extension entomologist Tim Waters said during a recent presentation at the Hermiston Farm Fair.

Sweet potatoes were produced and sold in the Columbia Basin until a labor shortage triggered by World War II ended the crop’s run. Now could be an ideal time to bring the crop back because interest is high for products such as sweet potato fries.

Lamb Weston recently built a multimillion-dollar plant in Louisiana strictly to process sweet potatoes, and processing lines here are capable of handling the crop, said Don Horneck, the Oregon State University Extension agent.

“There certainly is demand,” he told the Capital Press newspaper.

Because few broadleaf herbicides are registered for the crop, and because sweet potatoes need high humidity to excel, it’s not a given that Northwest growers will be able to produce bountiful harvests.

Horneck estimated growers need to average 15 tons an acre or more to generate a profit.

Waters said that in two years of trials near Pasco, he was getting upward of 15 tons to an acre in well-irrigated sites. In one instance, at high irrigation levels, the crop yielded 24.5 tons to an acre, well above yields in Louisiana and California.

Yields fell to as low as 5 tons to an acre in plots that received minimal water, Waters said.

“If you do grow sweet potatoes, don’t let them get dry,” he said.

Waters, who also tried growing sweet potatoes near Moses Lake, said the warmer sandy soils near Pasco produced far better yields, as did pushing back harvest dates.

“The later you can push the harvest, as long as you have warm weather, the yields keep going up,” Waters said.