LAKE COUNTY — For the past week, the hum and drone of wind machines and water sprinklers has been audible across the county, protecting the tender leaf buds of grapes, walnuts and also pear blossoms from cold temperatures.
Frost protection is a sometimes all-night ordeal of checking temperatures and making sure the frost protection is running smoothly. It all pays off by protecting the coming crop. In May, frost danger is over and crop growth well underway in the warm weather.
A dry December forced a later-than-usual application of dormant oil spray on pear orchards that protects the delicate crop from insects, according to long-time pear and walnut farmer Broc Zoller. As a result of the late January and early February spray applications, which stimulates bloom, it”s taking about five days longer than last year for all orchards in the county to reach full bloom.
“Even though there is some frost injury, a lot of the blossoms will fall off, but we have plenty ? too many ? we need to lose some of them anyway,” Zoller said. He said this year most orchards hit the mid-point of bloom starting March 26 to the end of the month.
“We had a light crop last year. This year it”s looking pretty good. We”re all worried because it could rain, but when it”s not raining it means you have cold nights. It gets old, when it”s night after night,” Zoller said of running frost protection.
Wind machines are used when temperatures are not expected to drop quickly during the night. They stir up the warmer, top level of air with the cooler air near the ground.
Water protection is a continuous sprinkler application that freezes over the vines and branches. As long as it is applied continuously until sun-up, it will prevent the crops from freezing. For every gram of water that changes to ice, 80 calories of heat is released, Zoller said.
Nearly every night for the past week grape grower Steve Devoto has slept out in a trailer surrounded by his 115 acres of vines. He said running a wind machine is “a bit cheaper than running water.” He gauges which to use based on the temperatures in the early evening. “Earlier this week it hit 42 degrees at 10:30 p.m., the wind machine would never protect on a night like that,” Devoto said.
Thursday morning the temperature dropped to 35 degrees at 2 a.m., and Devoto switched the wind machines on. At this point vineyard farmers cannot tell what kind of frost injury the buds received. That will be evident when the leaves are out. Frost burns appear brown and badly burned leaves are black on the edges, Devoto said.
One method of frost protection that farmers began giving up starting in the 1970s is the smudge pot. The heaters use pricey diesel and most can be seen discarded in piles on orchard and vineyard property while farmers avoid using them with fuel costs reaching above $4.
The costs of frost protection are balanced out by the fact that in cold weather, irrigation is not needed. Irrigation is more costly because more water is required. But labor in orchards can be pricey. Agriculture was the only industry sector over the winter where employment substantially grew in the county, because labor is required for pruning, spraying, leaf-pulling and thinning clusters on grapes and planting. The farm sector added about 200 jobs from February 2007 to February 2008, according to the North Coast Region of the Labor Market Information Division.
Contact Elizabeth Wilson at ewilson@record-bee.com
