Drift smoke from the Ferguson Fire has some Tuolumne County vintners and agriculturalists concerned about the commercial viability of the early fall grape harvest, but one forestry official with the University of California noted that the native wilderness of the Mother Lode has a developed adaptability to smoky conditions.
Susie Kocher, forestry and natural resources advisor with the University of California Department of Agriculture and Natural Resources Central Sierra Cooperative Extension, said that “smoke taint” of commercial agriculture was always a concern during fire season.
“It’s grapes we worry about the most,” she said. “In the past there have been bad years when there was a lot of smoke where grapes were on the vine and wineries had to produce the smoky wine because of that effect.”
But the issue of smoke taint, or when agriculture absorbs the “free volatile phenols” created by burning wood and develops sensory characteristics of smoke or ash, was a modern issue characteristic of a developing civil infrastructure, Kocher said.
Over a century ago, Native Americans living in the wilderness areas would naturally set fires in the area to burn the understory of organic material that build up with the forests, Kocher said. Fires started naturally as well, often by lighting.
“In the past, around about Sonora, those areas burned every 10 years on average,” she said. “Our wildlife is adapted to a smoky and wildfire environment.”
According to some teachings, “native people even said trees like smoke,” Kocher said.
“It’s part of the traditional ecological knowledge of native tribes that smoke is good for trees,” she said. “That's not a scientifically proven thing. We don't know.”
Every summer in the past, residents would expect and anticipate a smoky summer, she said. But the effort to reduce forest fires around the year 1910 created a “huge fuel accumulation” creating more dangerous (and even smokier) fire seasons.
The smokier fire seasons and threat of crop pollution is an imminent concern for local vintners, many of whom harvest in the early fall.
Ron Harms, owner of Yosemite Cellars in Groveland with his wife Cheryl, said the Ferguson Fire smoke drew parallels to the 2013 Rim Fire, which created an almost entirely smoke tainted harvest that year.
“We don't think the smoke impact at the moment is as bad as 2013 but we are concerned because now we have a prolonged period of time at least for a significant portion of the day our grapes are being bathed in smoke,” he said.
Unlike most other agricultural products, the skins of grapes are permeable, he said. When the smoke particles (made of varying particulates and hydrocarbons based on the material burned) adhere to the grape skins, it becomes part of the grape itself.
“It isn't something you can just wash off,” he said. “The effect on fruit flavors is more pronounced as the fruit gets riper. We are concerned and trying to be patient to see how things play out.”
In 2013 during the Rim Fire, the thick fog of smoke lingered on the Harms’ vineyard just 30 days prior to harvest.
They had to “salvage” the grapes for a commercial product, he said and created a blend of the 2012 vintage and the smoke-tainted wine. The “Rim Fire Blend” was successful, he said, but there was a fine line with the smoky characteristics of grapes.
“People's palettes are different in terms of their smoke sensitivity. Some people just can't tolerate them at all,” he said. “The smoke content in 2013 was just very pronounced we just had to find a way to minimize or reduce it.”
Harms said he plans to harvest his current crop in mid to late September.
But all agricultural products do not appear to be susceptible to smoke taint. Though the smoke can cause respiratory problems in humans and in animals, some the characteristics of certain fruits provide a natural resistance to the smoke.
Barbara Leach, owner of the Deer Creek Cherry Farm in Groveland with her husband Time, said she had already harvested her crop this summer before the start of the Ferguson Fire. It was only the composition qualities of cherries which made her believe that the smoke could have been a detriment to the crop, she said.
“I'm guessing if we had this quantity of smoke and this density of smoke when my cherries were ripening it probably would affect the quality,” she said.
But her home orchards and apple trees appeared to be virtually unaffected, she said.
The University of California Division of Agriculture and Natural Resources provides information about the effects of wildfire on agricultural and livestock, and one document from Michigan State University noted that “all fruits are susceptible, however, wine grapes are particularly vulnerable.”
Further in the agricultural process, some growers have expressed concerns that the wildfire can also negatively affect water resources and irrigation systems for commercial farming.