- Author: Pamela Kan-Rice
UPDATED: Viticultural area is Kelsey Bench, not Kelseyville Bench.
UC Cooperative Extension study shows smoke damage to grapes not uniform across vineyards
By the time the Mendocino Complex Fires were officially contained on Oct. 4, 2018, five weeks after igniting, they had burned approximately 450,000 acres in Colusa, Lake, Glenn and Mendocino counties, making it the largest wildfire in California history, according to CalFire.
The fire not only destroyed 280 homes and other buildings, its smoke destroyed the market for wine grapes grown in vineyards near burned areas.
Fearing grapes near the fire would impart smoke flavors to the wine, some wineries rejected all fruit from nearby regions of Lake County and Potter Valley, leaving grape growers to hastily find new destinations for their 2018 crop.
“It can be difficult to determine if fruit has been compromised in quality when exposed to wildfire smoke, and whether or not smoke flavors will result in wine when fermented,” said Glenn McGourty, UC Cooperative Extension advisor in Mendocino County.
A new UC Cooperative Extension study shows wind direction and speed, temperature and a vineyard's proximity to an active fire are factors that can help growers and winemakers predict smoke damage to fruit.
“Fruit in my own vineyard, 60 feet across the street from where the fire started, had no smoke damage because the wind was blowing away from it,” McGourty said.
$41 million hit to wine grape sales
Due to the Mendocino Complex Fires, an estimated $41 million worth of winegrapes, which would have been sold at full price, were impacted – some were sold at a discount, some were sold to other customers, some were custom crushed, while some were left hanging in the vineyard, according to the Lake County Winegrape Commission and Mendocino County Farm Bureau.
The wine industry needed a scientific method of determining whether grapes could be made into a wine untainted by smoke. With funding from the Lake County Winegrape Commission, McGourty formed a workgroup of local growers and winemakers with Anita Olberholster, UC Cooperative Extension enology specialist in the Department of Viticulture & Enology at UC Davis, to research when fruit quality has been compromised.
“The need for industry standards regarding the impact of wildland smoke on winegrapes and the resulting wines has become even more pressing over the past few years,” said Debra Sommerfield, president of the Lake County Winegrape Commission.
Science showed the intensity, duration and timing of the exposure to wildfire smoke affects the grape's uptake. Generally, the closer to harvest, the greater risk to the fruit.
“Both the fruit and wine samples in our study showed a wide range of volatile phenol and glycocide concentrations, indicating that smoke damage to fruit was not uniform across the vineyards sampled,” McGourty said.
Volatile phenols and glycosides create off-flavors
Fresh smoke contains volatile phenols and glycosides that can affect fruit, but these chemicals tend to dissipate in the atmosphere in 1 to 2 hours. Vineyards close to actively burning fires and in the path of fresh smoke are most likely to be affected by smoke taint. Smoke that travels long distances is less likely to affect grapes and the wine made from the fruit.
The combination of volatile phenols and glycosides create “smoke taint” – both aromatic and tactile in the mouth. Wine drinkers may smell smoke or other off flavors and experience a drying of their mouth when high concentrations of the chemicals are present in wine.
“At lower concentrations, smoke taint reminds you of brett-affected wines,” Oberholster explained, referring to the yeast brettanomyces. “There is a shortness of fruit, a kind of dryness in the mouth that you know isn't normal. There may be barely perceptible aromas that aren't normal as well.”
Following wildfire smoke exposure, the researchers sampled fruit from 14 cabernet sauvignon vineyards around the viticultural areas of Lake County, including Upper Lake, High Valley, Big Valley, Kelsey Bench, Red Hills, Lower Lake and Guenoc Valley. As a control, fruit was also sampled from a Napa Valley vineyard that was not exposed to wildfire smoke.
“The volatile phenols guaiacol and 4-methyl guaiacol are detected in the fruit by gas chromatography, so it is possible to sample fruit before harvest to make picking decisions,” McGourty said. “Based on our study, berry sampling and guaiacol/ 4-methyl guaiacol analysis are useful for a quick evaluation of whether or not fruit from a particular vineyard may have the presence of volatile phenols that can potentially result in smoke-affected wine.”
Testing the fruit for volatile phenols and glycosides is both expensive and not completely predictive as standards are not well defined for damage based on smoke chemical concentration, he cautioned.
These two compounds aren't the only ones that cause smoke flavors. More than 70 other compounds in forest fire smoke can also produce undesirable flavors and odors described as “like licking an ash tray, burnt garbage, a burnt potato, a campfire that has been drenched with water.”
The taste test
To assess the levels of the compounds that produce the off-flavors, Oberholster convened a panel of 14 wine industry professionals to taste the sample wines. The wine tasters detected stronger off-flavors in the wines made from riper fruit, which also contained higher concentration of smoke compounds. Less than 6 micrograms per liter of the smoke compounds were difficult for the tasters to detect, leading the researchers to conclude they will have a minimal effect on wine quality.
Smoke from a distant fire
The scientists also looked at the influence of distance from the fire and elevation on smoke taint. They found some vineyards close to the edge of fires and immediately downwind were heavily affected, with the grapes containing high concentrations of the smoke flavor-causing compounds. But they determined elevation was not a factor in smoke flavors in wines.
Wind direction and speed, temperature and vineyard proximity to active fires are highly likely affect whether there will be smoke damage to the fruit, their research showed.
“Smoke generated in the first one or two hours from a wildfire is most damaging to nearby vineyards,” McGourty said. “Even though a vineyard may be enveloped in smoke, if the source of the smoke is from a distant fire, it will probably won't seriously damage the fruit quality because most of the volatile gases are gone.”
Lake County Winegrape Commission's Sommerfield said, “Today, the results of this study are already proving to be useful in deepening our understanding of smoke and the risks it poses to grapes and wine, in enabling grape growers and winery buyers to engage in fruitful discussions and make informed decisions, and, in turn, in helping to propel the development of industry standards and protocols.”
To read more about the study by McGourty, Michael I. Jones, Oberholster and Ryan Keiffer, see the January 2020 edition of Wine Business Monthly at https://www.winebusiness.com/wbm.
“This is a great little study, the first one that I know of that takes a systems approach to evaluating the effects of wildfire smoke,” said McGourty.
Glenn McGourty, UCCE viticulture advisor for Mendocino County, describes for Hannah Bird the UC project to analyze the effect of wildfire smoke on winegrapes.
- Author: Pamela Kan-Rice
Fire Impact and Risk Evaluation (FIRE) survey.
“We will aim to quantify the impact of wildfires in different livestock production systems,” said Beatriz Martínez López, director of the Center for Animal Disease Modeling and Surveillance in the UC Davis School of Veterinary Medicine. “The idea is also to create a risk map showing areas more likely to experience wildfires with high economic impact in California.
“This economic and risk assessment, to the best of our knowledge, has not been done and we hope to identify potential actions that ranchers can take to reduce or mitigate their losses if their property is hit by wildfire.”
Martínez López, who is also an associate professor in the Department of Medicine & Epidemiology at UC Davis, is teaming up with UC Cooperative Extension livestock and natural resources advisors and wildfire specialists around the state to conduct the study.
“Right now, we have no good estimate of the real cost of wildfire to livestock producers in California,” said Rebecca Ozeran, UC Cooperative Extension livestock and natural resources advisor for Fresno and Madera counties. “Existing UCCE forage loss worksheets cannot account for the many other ways that wildfire affects livestock farms and ranches. As such, we need producers' input to help us calculate the range of immediate and long-term costs of wildfire.”
Stephanie Larson, UC Cooperative Extension livestock and range management advisor for Sonoma and Marin counties, agreed, saying, “The more producers who participate, the more accurate and useful our results will be.”
“We hope the survey results will be used by producers across the state to prepare for wildfire,” said Matthew Shapero, UC Cooperative Extension livestock and natural resources advisor for Ventura and Santa Barbara counties, “And by federal and private agencies to better allocate funds for postfire programs available to livestock producers.”
The survey is online at http://bit.ly/FIREsurvey. It takes 15 to 30 minutes, depending on the number of properties the participant has that have been affected by wildfire.
“Survey answers are completely confidential and the results will be released only as summaries in which no individual's answers can be identified,” said Martínez López. “This survey will provide critical information to create the foundation for future fire economic assessments and management decisions.”
- Author: Jeannette E. Warnert
University of California Agriculture and Natural Resources (UC ANR) is a division of the University with scientists based on three UC campuses and in UC Cooperative Extension offices serving all California counties. UC ANR conducts research and shares research-based information with the public about wildfire, agricultural production, environmental stewardship, water policy, youth development and nutrition.
Travis Bean
UC ANR Cooperative Extension weed specialist at UC Riverside
Management of invasive plants that introduce or alter fire regimes
(951) 827-5130
travis.bean@ucr.edu
Van Butsic
UC ANR Cooperative Extension specialist at UC Berkeley
Land change science including fire and land use planning
(510) 666-5400
vanbutsic@berkeley.edu
Sabrina Drill
UC ANR Cooperative Extension natural resources advisor for Los Angeles and Ventura counties
Plant arrangement, building design and maintenance to reduce fire risk, invasive weeds and pests contributing to fire risk
(626) 586-1975
sldrill@ucanr.edu
Maggi Kelly
UC ANR Cooperative Extension natural resource monitoring specialist
Geographic information science, mapping forests
(510) 642-7272
maggi@berkeley.edu
Susan Kocher
UC ANR Cooperative Extension natural resources advisor in the Central Sierra
Fire adapted communities, fire hazard mitigation in forests, post fire restoration
“Living with Fire in the Tahoe Basin” website, http://www.livingwithfire.info/tahoe/
(530) 542-2571
sdkocher@ucanr.edu
Chris McDonald
UC ANR Cooperative Extension natural resources advisor
Desert species, invasive plants and fire
(909) 387-2242
cjmcdonald@ucanr.edu
Richard Minnich
Professor of earth sciences, UC ANR Agricultural Experiment Station, UC Riverside
Fire ecology of Southern California, Baja California, and temperate Mexico; exotic plant invasions, climate change.
(951) 827-5515
minnich@ucr.edu
Max Moritz
UC ANR Cooperative Extension wildfire specialist in the Department of Environmental Science, Policy and Management at UC Berkeley. He is located in Santa Barbara County.
Wildland fire, fire modeling, fire effects, shrubland ecosystems and spatial patterns of fire disturbance, climate change adaptation
mmoritz@berkeley.edu
Malcolm North
Associate professor of Forest Ecology, UC ANR ecologist
Forest recovery
(530) 754-7398
mpnorth@ucdavis.edu
Lenya Quinn-Davidson
UC Cooperative Extension Area fire advisor - Northern California
Fire ecology and management
(707) 445-7351
lquinndavidson@ucanr.edu
Dave Rizzo
Plant pathology professor, UC ANR pathologist
Fire and infectious disease
(530) 752-0300
dmrizzo@ucdavis.edu
Kimberly Rodrigues
UC ANR Cooperative Extension natural resources advisor
Public participation in resource management
(530) 750-1283
karodrigues@ucanr.edu
Ricky Satomi
UC Cooperative Extension area forestry and natural resources advisor in Shasta, Trinity and Siskiyou counties
Forest management and wood use
(530) 224-4900
rpsatomi@ucanr.edu
Mark Schwartz
Environmental science professor at UC Davis and UC ANR ecologist
Forest plot mapping
(530) 752-0671
mwschwartz@ucdavis.edu
Tom Scott
UC ANR Cooperative Extension area natural resources wildlife specialist for Southern California
Conservation of wildlife, wildlife management at the urban-wildland interface, and response of plants and animal species to fire
(951) 827-5115
thomas.scott@ucr.edu
Scott Stephens
Professor of fire science and co-director Center for Fire Research and Outreach at UC Berkeley, UC ANR fire scientist
Fire ecology, fire behavior, wildfire, fuels treatments, forest mortality, fire policy
(510) 642-7304
sstephens@berkeley.edu
Bill Stewart
UC ANR Cooperative Extension forestry specialist in the Department of Environmental Science, Policy and Management at UC Berkeley and co-director Center for Fire Research and Outreach
Economics of fire prevention and fire suppression programs
(510) 643-3130
billstewart@berkeley.edu
Yana Valachovic
UC ANR Cooperative Extension forest advisor in Humboldt and Del Norte counties and member of the Northern California Fire Science Consortium hub
Home and landscape design considerations for wildfire, prescribed fire, forest health and prescribed fire, wildfire and fuels in redwood, Douglas-fir and tanoak forests, fire education
(707) 445-7351
yvala@ucanr.edu
Kate Wilkin
UC Cooperative Extension forestry/fire science and natural resources advisor
Sutter, Yuba, Butte and Nevada counties
Fire ecology and management, fuels treatments and fire policy
(530) 822-7515
kwilkin@ucanr.edu
For more information, contact: Jeannette Warnert, (559) 240-9850, jewarnert@ucanr.edu and Pam Kan-Rice, (510) 206-3476, pam.kanrice@ucanr.edu
- Author: Jeannette E. Warnert
One focus of UC Agriculture and Natural Resources (UC ANR) is forestry, and a host of its researchers study the impacts of fire and fire suppression in California wildlands. This expertise is valued by the public and the news media in times when wildfires strike.
The 2017 fire season has been the most severe on record, due to a combustible combination of drought, rains, and especially, wind. “What really makes big years in terms of acres burned is essentially how many really windy days we have,” UCCE forestry specialist Bill Stewart told KPCC. Last year's wet winter, which led to increased vegetation, and this year's record-breaking heat waves aren't as indicative of fire danger as Santa Ana winds, known in Northern California as Diablo winds, Stewart said. “It's always dry. There's always fuel,” he said.
UC Cooperative Extension specialist Max Moritz said the state needs to incorporate wind corridors into its fire hazard severity zone maps, according to an article on ScienceMag.org. Stricter building codes apply in places designated as high-risk.
UC ANR scientists also generate local fire recovery and mitigation resources for the public in wildfire-prone counties.
Links to all the sites have been aggregated on a UC ANR story map - https://arcg.is/0SWyW8. This story map may be freely shared on websites and social media. (Find the share URL and the embed code by clicking the share icon on the upper right hand corner of the story map.)
Local UC Cooperative Extension fire resources websites listed on the story map are:
Northern California
UCCE Central Sierra fire resources
UCCE Mendocino County fire resources
UCCE Sonoma County fire resources
UCCE Sutter-Yuba counties fire resources
Central California
UCCE Mariposa County fire resources
UCCE San Luis Obispo County fire resources
Southern California
UCCE San Diego County fire resources
UCCE Santa Barbara County fire resources
The following general information on wildfire recovery is available for those who were directly impacted by the wildfire.
Homeowners guide to recovering from wildfire
Landowners guide to recovering from wildfire
Livestock, agriculture and natural resources guide to recovering from wildfire
Don't get burned twice (pdf)
Recovering from wildfire: A guide for California's forest landowners (pdf)
The site also provides information for those whose homes were spared in 2017, but now wish to take precautions to reduce the risk of wildfire damage in the future.
Homeowner's wildfire mitigation guide
Sustainable and fire-safe landscapes
Home survival in wildfire-prone areas (pdf)
- Author: Pamela Kan-Rice
To help people prepare, CAL FIRE has a checklist for evacuation online at http://www.readyforwildfire.org/Evacuation-Steps. UC Agriculture and Natural Resources scientists contributed to the research behind the recommendations.
A one-page checklist online at http://disastersafety.org/wp-content/uploads/2016/07/IBHS-Wildfire-Last-Minute-Checklist.pdf, also based on research by UC ANR scientists, is available from the Insurance Institute for Business & Home Safety.
Napa County residents have been told to be prepared in case they need to leave.
“We have team members tending to their own homes and or family's needs, providing support in shelters, and being available for immediate clientele needs in any way they can,” said David Lewis, UC Cooperative Extension director in Napa and Marin counties. “We look forward to calling upon UC colleagues with more experience to support our communities in the long recovery period. For the immediate future, we will stay focused in our efforts to support evacuation and shelter efforts – personal safety and needs are priority one until the fires no longer pose a threat.”
The main thing to remember when preparing to evacuate is to protect your life first.
“Don't die trying to prepare your house before you leave,” said Yana Valachovic, UC Cooperative Extension director and forest advisor in Humboldt and Del Norte counties. “Monitor the situation, watch the wind directions, and listen to all emergency personnel.”
To receive timely updates on fire conditions, Brian Oatman, UC ANR Risk & Safety Services director, uses Nixle. “While some communication methods may not work due to outages, the more sources we have, the better the chance that the message gets through,” Oatman said. To sign up for text alerts, visit http://www.nixle.com or text your zipcode to 888-777 to opt-in.
“We have coordinated with CropMobster to create a resource list at https://sfbay.cropmobster.com/bay-area-fire-resources where anyone can post any needs or offer help of any kind,” said Stephanie Larson, UC Cooperative Extension director in Sonoma County. “UCCE Sonoma has also created a Disaster Recovery for Agriculture Operations at http://cesonoma.ucanr.edu/Disaster_Resources for homeowners and managers of rangelands. UCCE is working closely with Sonoma County to provide UC ANR resources to assist with the recovery of our community that has been devastated by this fire.”
In Yuba County, the Cascade fire is 45 percent contained as of Oct. 12. “Evacuation orders are being lifted in parts of Yuba County,” said Janine Hasey, UC Cooperative Extension director for Sutter and Yuba counties. “Kate Wilkin, our new UC Cooperative Extension forestry, fire science and natural resources advisor in Sutter, Yuba, Butte and Nevada counties, has assembled resources for residents who are returning to their homes at http://cesutter.ucanr.edu/Fire_Information. We will be updating the website with more recovery information in the coming days.”