Frost Control

Orchard heaters were introduced to the Yakima Valley in the early 1900s. These earliest heaters - called smudge pots - were simply metal containers filled with fuel and ignited. Common fuels were heavy oils, such as diesel. Old rubber tires were sometimes used, often filled with sawdust. The burning smudge pots gave off oily smoke that could be seen as a dark fog blanketing the valley. On cold days school children were instructed to wash their faces, hands, and collars. The smoke left a residue on anything that was outside, including children on their way to school.

Influenced by a growing national concern for the environment, the Yakima County Commissioners banned the burning of heavy oils in open containers with passage of a crop heating ordinance on December 15, 1965. Growers had a five-year grace period to find a better way to combat frost. This need, combined with rising fuel prices, was a call for new technological innovation. More efficient heaters are now used. These have a "return stack" which recirculates smoke and vapors back into the heater.

Overhead and undertree sprinklers are also used in cold weather to encase young blossoms in a coat of ice. As the water freezes on the blossom, heat is given off, protecting the fragile bloom from the deadly cold.

Another innovation to combat cold is the wind machine. Mounted on 30' columns, these giant fans mix the warm air above the orchard with the cooler air close to the ground. This raises the temperature around the apple trees.