ONTARIO, Ore. — Brandon Leon liked what he saw on the Oregon State University onion research plots — and during the hour’s drive from Boise.

“I see water everywhere,” he said, referring to Treasure Valley irrigation canals visible from Interstate 84.

In contrast, California’s onion growers are impacted by that state’s tight supply of water, said Leon, based in Tipton, Calif., with seed company Hazera.

The water supply to the southeastern Oregon-southwestern Idaho crop was unexpectedly good following an unusually wet spring. The region supplies about a quarter of the country’s fall storage onions.

But the crop faced its share of challenges such as early cold, high winds that forced some replanting and a quick transition from cold to hot. The number of 100-degree days broke the 2003 record.

“It has been stressful on the onions,” Erik Feibert, a senior faculty research assistant at OSU’s Malheur Experiment Station, said at the annual Onion Variety Day Aug. 24.

Kyle Wieland, farm manager at OSU-Malheur, said this year had more hot nights than usual, giving onions less of a reprieve from the hot days.

Feibert said this year has been good for putting varieties to the test. Some have shorter or longer maturation periods. Harvest technique, bulb size and color, and market usage also vary.

Brad Watson, production manager with J.C. Watson Co. in nearby Parma, Idaho, said he looks for onion qualities including shape, size, consistency and disease resistance.

He said the selection of desired characteristics increased in recent years, and “not everybody wants the same thing.”

Wieland said benchmark, highest-quality plants and bulbs often are found at field’s edge, where competition comes from one side only.

Feibert said the control of thrips, a major insect pest for onions, has been effective this year. Factors include fine-tuned chemical mixtures, and optimizing how and when they are applied.

Stuart Reitz, who directs the experiment station, said this is the third year a tall tractor sprayer has been used. It allows precise insecticide and fungicide applications through the season.

Previously, staff could only do a couple of sprays. Subsequent applications were done by aircraft, which “on our little field were never effective,” he said. The new sprayer “really helps out.”

Reitz said the field day showcased 58 varieties.

Growing-degree days, or heat units, are ahead of the 30-year average by a few days but remain behind 2021, he said. Prolonged high heat arrived about a month early last year.

Onion plants do not grow well in temperatures below 50 or above 86 degrees, Reitz said.

Leon said all of a season’s variables will influence onions’ growth and quality.

Lyndon Johnson of Caldwell, Idaho, seed producer Crookham Co. said that while the number of big bulbs likely will fall below long-term averages in the region, “the quality is there.”