- 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
The cultural practices described represent the establishment and production operations, as well as materials of a well-managed cabernet sauvignon vineyard in this region. The costs, materials, and practices shown in this study will not apply to all farms. Growers, UC ANR Cooperative Extension farm advisors, and other agricultural associates provided input and reviewed the methods and findings of the study.
The hypothetical 200-contiguous-acre farm is located in Crush District 11, which includes San Joaquin and Sacramento counties. The economic life of the grower-owned-and-operated cabernet sauvignon vineyard used in this cost analysis is 25 years. Vine management includes hand operations such as pruning, suckering, shoot removal and positioning. The grapevines are mechanically trimmed and harvested. This study does not include cluster thinning, but other winegrape varieties may require thinning due to compactness.
The authors describe the assumptions used to identify current costs for establishment and production of the winegrapes, material inputs, cash and non-cash overhead. Ranging analysis tables show profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.
The new study is titled “Sample Costs to Establish a Vineyard and Produce Winegrapes- Cabernet Sauvignon Variety, San Joaquin Valley North, San Joaquin and Sacramento Counties – 2016.”
Free copies of this study and sample cost-of-production studies for many other commodities are available. To download the cost studies, visit the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu.
The cost and returns program is funded by the UC Agricultural Issues Center, which is part of UC Division of Agriculture and Natural Resources, and the UC Davis Department of Agricultural and Resource Economics.
For additional information or an explanation of the calculations used in the studies, contact Jeremy Murdock at the Agricultural Issues Center at (530) 752-4651 or jmmurdock@ucdavis.edu or UC Cooperative Extension San Joaquin County farm advisor Paul Verdegaal at psverdegaal@ucanr.edu.
- Author: Pamela Kan-Rice
A new study on the cost and returns of producing winegrapes in the North Coast region's Russian River Valley, an American Viticulture Area in Sonoma County, has been released by the UC Agricultural Issues Center and the UC Davis Department of Agricultural and Resource Economics.
The cultural practices described represent production operations and materials of a well-managed vineyard in this region. The costs, materials and practices shown in this study will not apply to all farms. The production focuses on two varieties, chardonnay and pinot noir. Growers, UC Cooperative Extension farm advisors and other agricultural associates provided input and reviewed the methods and findings of the study.
The authors describe the assumptions used to identify current costs for production of the winegrapes, material inputs, cash and non-cash overhead. Ranging analysis tables show profits over a range of prices and yields for each variety. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.
The new study is titled “Sample Costs to Produce Winegrapes, Chardonnay and Pinot noir, North Coast Region Russian River Valley, Sonoma County – 2016.”
Free copies of this study and other sample cost of production studies for many commodities are available. To download the cost studies, visit the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu.
The cost and returns program is funded by the UC Agricultural Issues Center, which is part of UC Division of Agriculture and Natural Resources, and the UC Davis Department of Agricultural and Resource Economics.
For additional information or an explanation of the calculations used in the studies, contact the Agricultural Issues Center at (530) 752-4651, Donald Stewart at destewart@ucdavis.edu or Rhonda Smith, UC Cooperative Extension advisor in Sonoma County, at (707) 565-2621 or rhsmith@ucanr.edu.
- Author: Pamela Kan-Rice
UC studies examine costs for growing pears, walnuts, winegrapes
Analysis for each crop is based upon hypothetical farm operations using practices common in the region. Input and reviews were provided by UC Cooperative Extension farm advisors, researchers, growers, farm accountants, pest control advisers, consultants and other agricultural associates.
The studies describe the assumptions used to identify current costs for the individual crops, material inputs, cash and non-cash overhead. A ranging analysis table shows profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs and the whole farm annual equipment, investment and business overhead costs.
The four new cost studies are the following:
- Sample Costs to Establish and Produce Pears, 2012, North Coast, by Rachel B. Elkins, Karen M. Klonsky and Kabir P. Tumber.
- Sample Costs to Produce Organic Pears, 2012, Sacramento Valley, by Chuck A. Ingels and Karen M. Klonsky.
- Sample Costs to Establish a Walnut Orchard and Produce Walnuts, 2012, North Coast, by Rachel B. Elkins, Karen M. Klonsky and Kabir P. Tumber.
- Sample Costs to Establish a Vineyard and Produce Winegrapes (Cabernet Sauvignon), 2012, San Joaquin Valley North, by Paul S. Verdegaal, Karen M. Klonsky and Richard L. De Moura.
These cost studies and cost of production studies for other crops are available online at http://coststudies.ucdavis.edu, at UC Cooperative Extension offices and by calling (530) 752-3589. For more information about the studies, contact Richard De Moura at rdemoura@ucdavis.edu in the UC Davis Department of Agricultural and Resource Economics.
- Contact: Pam Kan-Rice, (530) 754-3912, pskanrice@ucdavis.edu
- Contact: Richard De Moura, (530) 752-3589, rdemoura@ucdavis.edu
Each analysis is based upon hypothetical farm operations using practices common in the region. Input and reviews were provided by UC Cooperative Extension farm advisors, UC researchers, growers, farm accountants, pest control advisers, consultants and other agricultural associates.
Each study describes the assumptions used to identify current costs for the individual crops, material inputs, cash and non-cash overhead. A ranging analysis table shows profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.
The new studies are as follows:
- Sample Costs to Establish an Orchard and Produce Almonds, 2012, Sacramento Valley, by Joseph H. Connell, William H. Krueger, Richard P. Buchner, Franz Niederholzer, Carolyn J. DeBuse, Karen M. Klonsky and Richard L. De Moura.
- Sample Costs to Establish a Walnut Orchard and Produce Walnuts, 2012, Sacramento Valley, by William H. Krueger, Richard P. Buchner, Janine K. Hasey, Joseph H. Connell, Carolyn DeBuse, Karen M. Klonsky and Richard L. De Moura.
- Sample Costs to Establish a Citrus Orchard and Produce Mandarins (Tango), 2011, San Joaquin Valley – South by Neil V. O’Connell, Craig E. Kallsen, Karen M. Klonsky, Richard L. De Moura and Kabir P. Tumber.
- Sample Costs to Establish a Vineyard and Produce Winegrapes (Cabernet Sauvignon), 2012, North Coast Region (Napa) by Monica L. Cooper, Karen M. Klonsky and Richard L. De Moura.
- Sample Costs to Establish a Peppermint Stand and Produce Peppermint Oil, 2011, Intermountain Region, by Rob Wilson, Daniel B. Marcum, Karen M. Klonsky and Richard L. De Moura.
All cost of production studies are available online at http://coststudies.ucdavis.edu, at UC Cooperative Extension offices or by calling (530) 752-3589. For more information about the studies, contact Richard De Moura at rdemoura@ucdavis.edu in the Department of Agricultural and Resource Economics at UC Davis.