(Jan. 12, POSTED 2:20 p.m. CST) The arctic weather front that descended on California’s San Joaquin Valley Thursday night could mean a short-term halt to the shipping of navel oranges.

Joel Nelsen, president of California Citrus Mutual, Exeter, said the industry is considering a two-week moratorium on shipping fruit harvested after the freeze.

“We’ll make a final decision early next week after we’ve been able to evaluate potential damage,” Nelsen said Jan. 12.

Nelsen said temperatures in Tulare County, California’s top citrus growing county, dipped to 23 degrees shortly before dawn Friday. Yet, he said growers reported minimal damage.

“There were some isolated pockets that got hit harder,” Nelsen said.

Temperatures Thursday night and Friday morning were lower than had been predicted. The National Weather Service had forecast overnight temperatures in the valley above 25 degrees.

Temperatures are forecast to be colder Friday night and Saturday morning, 22-27 degrees, with Saturday night and Sunday morning temperatures of 23-29 degrees. A gradual warming is forecast to begin Monday.

Depending on wind and other factors, navel oranges suffer freeze damage when temperatures dip to 25 degrees for an extended period, usually several hours.

Should the shipping moratorium go into effect, Nelsen said there are enough navels in packinghouses to meet retailers’ demands for about a week. He said growers had accelerated picking the week of Jan. 8.

“But we still have about 70% of the navel crop on the trees,” Nelsen said.

If the shipping moratorium is implemented, Nelsen said the staffs of agriculture commissioners in each county would be asked to assist in determining whether fruit was damaged.

Freeze damage to navel oranges is not easily spotted. Nelsen said internal freezing damage might not be obvious for a week or more.

Citrus groves have already set fruit on the valley’s summer valencia orange crop. Nelsen said, however, it’s early enough in the growing pattern for valencias to heal themselves.

Citrus damage may not show for ‘a week or more’
A wind machine is ready for duty at a navel orange grove in eastern Fresno County, Calif. Two nights of a hard freeze are forecast for the San Joaquin Valley beginning Jan. 12. The wind machine, one of dozens in the valley, circulates the warmer air produced by irrigation water. California Citrus Mutual reported Jan. 10 that 75% of the navel orange crop was still on the trees, as was 72% of the lemon crop.