Heatwave poses threat to some yields, extension agent says

By MITCH LIES
Capital Press

The 2009 Columbia Basin potato harvest looks like a mixed bag with some potatoes scorched by a late-July heat spell, and others doing fine.

Washington State University Extension potato specialist Mark Pavek -- with some provisos -- projected the crop would be excellent.

"If we can keep vines green until mid-September, we're going to have some very high yields on a lot of potatoes," Pavek said.

Oregon State University Extension agronomist Don Horneck, on the other hand, projected yields would be down.

"That two weeks that it was hot was pretty brutal on some varieties," Horneck said. "It's going to be a down year for potatoes."

Growers, meanwhile, were predicting yields about average, with quality up.

"We've got a nice crop coming on," said Tony Amstad of Amstad Produce in Echo, Ore. "We're not looking for anything over average on the yield, but the quality is probably better than last year."

Randy Mullen, a Pasco, Wash., fresh-pack grower, estimated yields at slightly below average on his early varieties, but said yields were picking up as the season progresses. Mullen was wrapping up harvest this week.

"It started off slow, but it's getting better," he said.

Temperatures in Pasco topped 90 degrees for a 14-day stretch spanning the end of July and the first week of August, according to the National Weather Service. Temperatures topped 100 degrees eight of those days and peaked at 109 on Aug. 1.

Heat stress can cause multiple problems in a potato crop, Pavek said, including problems with specific gravity, heat necrosis, heat runners and irregular tuber growth.

One key to whether growers skirted problems, according to Dan Strebin of Strebin Farms, was water availability.

"On a lot of ground, you may only be able to put down 3 tenths or 35 hundredths of an inch per day," Strebin said. "So in a prolonged heat period, you can start running out of gas pretty quick.

"When it's up in the mid-90s and higher, that crop will use over 4 tenths of an inch of water per day," he said.

Strebin said he escaped problems on his acreage.

"I heard some crop got knocked down in yield," he said, "but I expect our yields to be normal."

Pavek estimated earlier this week between 10 and 20 percent of the basin's crop was harvested.

"We've still got a long way to go," Pavek said.

Prices, meanwhile, are well down.

"We're getting about 50 percent of what we were a year ago," Amstad said.

Amstad said he is recouping only slightly more than his cost of production.

He was looking for a boost in the price after Labor Day.

"We hope to get the price back up once demand starts back up in September," he said.

Staff writer Mitch Lies is based in Salem. E-mail: mlies@capitalpress.com.