The weather this week is enough of a concern that state officials from Gov. Arnold Schwarzenegger to Secretary of Agriculture A.G. Kawamura issued weather advisories, telling state residents to expect temperatures to hit the low teens and 20s at night this weekend, with daytime highs in the 40s.

The National Weather Service (NWS) has issued a freeze warning for southern Lake County through Jan. 14. The agency reports an arctic airmass is moving into the region, accompanied by gusty north to northeast winds. Near record temperatures are possible in some areas of Northern California this weekend, NWS reported.

The cold temperatures expected this weekend could harm vegetation and crops, according to NWS.

The state's agriculture department urges residents to provide shelter for livestock and pets during the cold weather, and to move plants indoors or cover them with blankets or plastic to prevent freezing.

Rachel Elkins, a University of California Cooperative Extensive farm advisor for Lake County, said the weather offers the potential for “winter injury” to plants that aren't dormant.

Regarding those plants on your porch, Elkins cautioned, “Anything that's green and growing, you'd better get it in.”

She urges homeowners to cover citrus, and to move plants under cover if possible.

She's not worried about the region's pears. “The pears are pretty darn hardy,” she said, and can handle very cold temperatures.

“My biggest worry, quite frankly, is with people who have planted olive trees,” she said.

There are small pockets of olives grown around the county, mostly used for olive oil. Olives, she said, are evergreen and don't go dormant as some species of trees do.

“We have seen winter kill on olives in the state, especially on young trees that are vigorous,” she said.

For olives, she said, the harsh cold can injure the wood and cause the trees to die back.

For winegrapes, she said the vines can survive the cold temperatures if pruning isn't started too early.

Most local grape growers, she said, learned in the 1990s about very cold temperatures, when it got down to 6 degrees one year.

“People have learned since then not to start their pruning until after they know they've had a good dormancy onset,” she said.

When those lows hit in the 1990s, she said, some growers were pruning vines in November and December, which made the vines susceptible, particularly Cabernet Sauvignon grapes, which go dormant later.

Walnuts also can fare well in the cold in certain conditions, said Elkins.

“The walnuts can be a problem because they are quite susceptible to winter injury, especially when the ground is dry,” she explained.

Good moisture helps protect the walnuts, she said. If it's too dry and cold, a walnut tree's roots can become damaged.

She guessed that some of the local walnut trees could suffer some winter injury and weakened branches since there hasn't been much rain of late.

E-mail Elizabeth Larson at This email address is being protected from spambots. You need JavaScript enabled to view it..

 

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