An unseasonably warm winter in desert growing regions interrupted by a pre-Christmas frost is likely to cause shortages of lettuce, broccoli and cauliflower in January, grower-shippers say.

“By the middle of January we’re going to have volumes 20% to 30% lighter than normal straight across the board, all commodities,” said Art Barrientos, vice president of harvesting for Castroville, Calif.-based Ocean Mist Farms.

Light frosts hit Arizona’s Yuma region and California’s Imperial and Coachella valleys Dec. 19-21. No major damage was reported.

“It wasn’t the kind of ice that can change the deal,” said Mark Adamek, general manager for romaine and mixed leaf production at Salinas, Calif.-based Tanimura & Antle.

Growers were ready to welcome signs of relief from temperatures in the 70s and low 80s common since October. They prefer to see the thermometer in the low 60s, where it spent the last week or so, and brave sporadic freeze risks.

“The industry is so far ahead, we’ve all had to leave a lot of product in the field because it just grew too fast and had pretty rough quality,” Adamek said.

“My yields are two thirds to three quarters of what they should be,” he said. “Toward the end of January we could start seeing a reduction in supply just because we’re eating up our acres so quickly by leaving so much problem product in the fields.”

“If it does not stay cold – if it warms back up – I’m afraid we could finish desert production before the northern production area is ready,” Adamek said Dec. 21.

Since the desert deal began in the third week of November, heat has kept Ocean Mist’s vegetable crops in Coachella and Yuma anywhere from eight to 20 days ahead of schedule, Barrientos said.

“The whole desert region has been in that mode,” Barrientos said. “Now the weather has changed more toward the typical December and January, so crop growth has slowed down.”

“Typical cold temperatures are forecast now into January and that will likely include our share of frost mornings,” he said Dec. 21. “There’s no significant damage. If we get hit a few days of moderate to heavy frost, we will start seeing some epidermal pealing in the leaf lettuces.”

On lettuce, Adamek had little room to maneuver.

“I have to cut two more acres to get the boxes on my production schedule because I’m leaving a third of my crop on the ground,” he said. “As the weather cools off and we catch up with the crop, now I don’t have the boxes planned for because so many acres were cut ahead of schedule.”

Romaine shipping point prices out of Yuma were $6.95 to $7.65 for 24-count cartons Dec. 18, according to the U.S. Department of Agriculture. Year-ago prices were $6.95 to $8.50.

Broccoli and cauliflower, which dislike heat, even stopped growing for a while and were in low supply early in the desert deal, Adamek said.