Water from the Barra's reservoirs protect their grapevines during spring frosts.

California drought: A veteran winegrower weighs in – Video

Charlie Barra, a veteran of 68 grape harvests in Mendocino County says the 2013 / 2014 drought is the worst he has ever seen, including the the drought of 1978. When I sat down to ask Charlie questions on film for Ask a Winemaker about the drought, I was surprised to learn why he was concerned about the lack of water. I thought for sure that the vines would be lacking the following year without winter rains, but this is not his priority.

Frost protection is in fact the biggest problem with a dry winter. In the 1950’s Charlie pioneered the technique of spraying water on the buds as they start to in the early springtime when night time temperatures can still drop below freezing on a regular basis. Though he doesn’t say it here, this innovation was in fact critical to the modern day success of Mendocino.

As Charlie explains in the video, cold air sinks in a valley while warmer air rises, providing just enough protection for vines on a hillside to survive frosts that come after the vine starts to send out the year’s new growth. With the realization that they could spray budding vines with water and keep them from freezing, growers were then free to start moving en masse to the lower, often flatter and easier to farm, vineyard sites and the expansion of the Mendocino grape industry followed shortly thereafter.

Water from the Barra's reservoirs protect their grapevines during spring frosts.

Overhead sprinklers protect young vines during early spring frosts.

So how does water protect grape vines from freezing? By spraying water from overhead sprayers as temperatures drop below zero, a sheath of ice is formed around each bud. This seems like it would surely kill the vine, but as long as a small amount of water is continuously sprayed, the energy in the warmer water with maintain the ice at 32 degrees, which is still a survivable temperature for the buds. The Barra’s monitor the temperature on cold nights closely, only turning on the overhead sprinklers for the (generally) short periods late at night when the temperature plunges in and around Ukiah. So closely do the Barra’s monitor the temperature that Charlie and Martha rigged remote sensors that trigger an alarm in their bedroom when air temperature among the vines approaches freezing! For an explanation of this process by scientists, check out this information from the Department of Energy: Spraying plants to prevent cold damage.

In the video that follows, Charlie told us how the system works when he visited Chicago a few years ago. You might recognize Melissa Graham of Purple Asparagus asking Charlie about his techniques.

As Charlie explains, water in California is a precious commodity, and if you are obligated to buy it, water is very expensive. Every year since they were built in the early 1960’s the Barra’s reservoirs have refilled with winter rains, providing the Barra’s plenty of water to protect their vines from even the worst frosts and still have some left over for irrigation if needed during the summer.

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So what will happen to the crop in 2014? Certainly no one knows for sure. The Barra’s are thrilled to have had bumper harvests in 2012 and 2013 in terms of both quality and quantity of grapes from their land, but even the abundance of the last two years will only go so far. The reservoirs are dangerously low at the moment – lower than Martha has ever seen them. A few sprinkles in late January have given the family some hope that they might squeeze by come springtime.

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