Last December's frigid temperatures may have damaged 80 percent to 90 percent of Utah Valley's peach crop, and experts warn that 1991 winter weather isn't over yet.

Utah State University Extension Services agent Tony Hatch said that negative-teen temperatures in late December destroyed 90 percent of the state's stone-fruit crops (including peaches and apricots). Though those crops have provided only 20 percent to 25 percent of the valley's total fruit yield in the past, the losses still amount to a substantial loss in Utah County's $10 million annual fruit farming economy, said Hatch, the extension service's fruit specialist."Stone fruits are the third largest fruit crop in the valley. "And remember, we still have more winter months to get through."

Orem's W.M. Ercanbrack Fruit Ranch Co. owns 275 acres throughout Utah County, including peach orchards in Genola. Co-owner Randall Ercanbrack said Hatch's assessment seems very valid from his standpoint.

"It's still probably too early to give a precise estimate, but I'd put our peach losses at around 90 percent. We've gotten hit pretty severely, at least from the cuttings I've taken so far."

Ercanbrack said winter frosts prove frustrating for fruit farmers because, unlike spring frosts, farmers cannot use wind machines or portable heaters in their orchards.

"It's a hopeless feeling because all those precautions just aren't effective or cost-effective during the winter."

Peach buds are typically damaged by frosts during temperatures minus-10 and lower. Late-December temperatures in some orchards were substantially lower than that, destroying buds in the process, Hatch said.

Also, trees usually start barking over and hardening (including conserving fluids and sap) as early as fall, Hatch said. Autumn conditions for the past few years may have actually provided enough time for the trees to weather-proof themselves, but severe freezing can damage more than just buds, he said.

"(The latest frost damage) could have taken place even earlier than December. Earlier winter frost damage (during the February 1988 chill) may have sufficiently weakened some trees to the point that they couldn't winterize.

"If that were to happen, it could be disastrous. Where bud damage, which is bad enough, can damage crops for up to a year, these frosts can damage wood and provide a long-term headache."

Hatch said the valley's peaches have received substantial frost damage, either during spring or winter, for the past four years, so farmers have stopped concentrating on them so highly. In that crop's place, Utah County farmers have begun concentrating on tart and sweet cherry crops, which also may have been damaged in the frost.

"Cherries typically have a higher temperature threshold (bud damage usually occurs at temperatures minus-15 or below)," Hatch said. "It's too early to tell with cherries so far."

Ercanbrack said he expects a good crop of cherries from the farm's Santaquin orchards, so far at least. "Our sweet cherries may have been damaged, but with as heavy blooming as we've had, we could still come out quite nicely."

However, Ercanbrack's experience in the business has led him to be pessimistic about possible yields, he said. "We've still got a lot of winter and spring left. After then, I'll breathe a sigh of relief."