- Author: Jeannette E. Warnert
Many people enjoy the cool and refreshing peppermint flavor without knowing there are ingenious farmers and agricultural researchers working year-round to produce the naturally spicy bite of this holiday icon. Candy canes get their distinctive taste from the oil secreted under the leaves of Mentha × piperita, the bright green herbaceous perennial herb known as peppermint.
Peppermint, a cross between spearmint and wintermint, is America’s most popular mint flavor. Peppermint oil is an important ingredient not just in candy; it is used in toothpaste, mouthwash, gum, pharmaceuticals and beauty products.
The majority of U.S. peppermint is cultivated in the Pacific Northwest, where summer days are warm and long and nights are cool, minimizing the presence of a chemical that imparts a bitter taste in the mint oil. In far northern California – near the University of California’s Intermountain Research and Extension Center in Siskiyou County, plus in Lassen County and in the Fall River Valley of Shasta County – the soil and climate are equally hospitable to mint production.
UC researchers have experimented with mint for more than 50 years, said Rob Wilson, UC Cooperative Extension advisor and director of the Intermountain REC. But it wasn’t until the mid-1990s that interest in commercially producing California peppermint took off. The 2010 peppermint acreage in northeast California was more than 3,500 acres and valued at about $7 million.
“Farmers are excited to have a new cropping choice like mint,” Wilson said, “especially given the fact that we have fewer choices than most areas of California because of our short growing season. Mint has given our farmers a new crop to add to their rotations.”
California peppermint oil producers have stiff competition. A significant quantity of peppermint oil is now produced in China and India. But U.S. growers see the opportunity to set their product apart by applying their agricultural skill to producing exceptionally high quality oil. To do so, the growers rely on research to inform their decisions on irrigation, fertilization and pest control. Extensive work on ideal mint management has been conducted in the Pacific Northwest, but there is a need for additional research to study mint production and economic viability under California conditions.
Peppermint is grown in a fashion similar to other field crops common in the intermountain region and can be harvested with some of the same equipment used for alfalfa and forages, Wilson said. Farmers plant certified verticillium wilt-free rootstock in the fall, and the peppermint stand produces a crop for about five years.
When mint has reached maturity, farmers swath the field like alfalfa and leave the plants to dry a few days before raking them into windrows. Using a forage harvester, the peppermint crop is chopped into small pieces and blown into tubs. At the distillery, steam is forced through the tubs to extract the oil.
“In harvest season, there’s a fragrant aroma of peppermint in the air,” Wilson said. “Even driving by a still along the highway, you immediately notice the smell.”
Peppermint begins bearing a crop the first year after the fall planting, producing 40 to 90 pounds of mint oil per acre. In subsequent years, the crop produces 60 to 120 pounds of oil per acre.
Wilson and Dan Marcum, UCCE advisor in Shasta and Lassen counties, developed a cost study for establishing and producing peppermint oil in the intermountain region. The UC study notes the importance of determining a market channel for the oil before the mint is planted. Annual contracts for the oils are generally negotiated in the winter for the following season at a fixed number of pounds at a set price. It is risky to grow the crop without a prearranged contract because on the spot market growers are competing with imported mint oil, which can be produced in areas where lower wages and limited regulations cut the production cost.
A major risk associated with peppermint farming, the study reported, is producing oil of poor quality, for which there is little or no demand. For example, weeds harvested with the mint lower the quality of oil. Pigweed and other broadleaf weeds contaminate the peppermint oil with a weedy flavor note. Plant stress caused by inadequate water or nitrogen or by insect damage can also reduce oil quality.
IREC has more than five acres of peppermint and a small peppermint still for studying production and evaluating the quality of oil. Wilson, along Intermountain REC superintendent Don Kirby, is using this acreage to compare irrigation, fertilization and harvest management strategies in order to maximize peppermint oil yield and oil quality under local soil and climatic conditions.
The IREC peppermint acreage is also used to study insect management. Among the pests that can reduce peppermint oil quality are spider mites and a recently introduced insect pest, mint root borer. These pests prompt significant pesticide use. Given the highly sensitive watersheds and environment of the intermountain area, wide usage of pesticides is considered problematic. Propargite and chlorpyrifos, the most commonly used pesticides for spider mite and mint root borer control, are under regulatory scrutiny.
In 2010, with funding from a California Department of Food and Agriculture Specialty Crop Block Grant, Larry Godfrey, UC Cooperative Extension specialist in the Department of Entomology at UC Davis, and Kris Tollerup, UC Davis post doctoral researcher, along with Marcum and Wilson, began investigating mint yield and quality response to spider mite infestation, spider mite management methods in mint, and reduced-risk insecticides for mint root borer management. In addition, a study is under way to determine if sex pheromone mating disruption is a plausible tactic against mint root borer, and whether adjusting the timing of the insecticide improve mint root borer control. These research projects will continue in 2013.
In the two-minute video below, Wilson explains how UC researchers use a mini peppermint oil still.
- Author: Mao Vue
Four new studies showing establishment and production costs for conventional and organic avocados are now available from the University of California Cooperative Extension.
Analysis for the crop is based upon hypothetical farm operations using practices common in Ventura, Santa Barbara, San Luis Obispo, San Diego and Riverside counties. Data regarding establishment and production practices, inputs and prices were collected from growers, the University of California Cooperative Extension farm advisors, agricultural institutions, and supply and equipment dealers.
The studies describe the assumptions used to identify current costs for the crop, material inputs, cash and non-cash overhead, profitability analysis, and comparison between conventional and organic productions. 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:
- Avocado Sample Establishment and Production Costs and Profitability Analysis for San Diego and Riverside Counties, 2011, Conventional Production Practices, By E. Takele, G. Bender, and M.Vue
- Avocado Sample Establishment and Production Costs and Profitability Analysis for San Diego and Riverside Counties, 2011, Organic Production Practices, By E. Takele, G. Bender, and M.Vue
- Avocado Sample Establishment and Production Costs and Profitability Analysis for Ventura, Santa Barbara, and San Luis Obispo Counties, 2011, Conventional Production Practice, By E. Takele, B. Faber, and M.Vue
- Avocado Sample Establishment and Production Costs and Profitability Analysis for Ventura, Santa Barbara, and San Luis Obispo Counties, 2011, Organic Production Practice, By E. Takele, B. Faber, and M.Vue
For more information about the avocado studies, contact Etaferahu Takele, UC Cooperative Extension area advisor, at ettakele@ucanr.edu or by calling (951) 683-6491 in the UC Cooperative Extension, Riverside County office.
These cost studies and cost of production studies for other crops are available online at on the UC Davis Cost Study website, at UC Cooperative Extension offices and by calling (530) 752-3589.
- Author: Jeannette E. Warnert
Written by Rachael Long, UC Cooperative Extension advisor in Yolo County, the story chronicles the adventures of 9-year-old Jack, who is exploring Nevada’s Black Rock Range when he falls into a cave. Jack befriends a bat named Pinta and a coyote pup named Sonny, who are determined to help him find his way home.
The story of Jack was first told to Long’s now 16-year-old son. When he was young, Long would make up stories to tell him during their long daily commute from their home on a farm outside of town.
“Each day, the stories got more and more elaborate,” Long said, “and I incorporated my long-time interest in bats.”
Long’s father, a UC Berkeley biology professor, introduced her to the world of bats. She was an early member of Bat Conservation International and she took a field class through the organization in 1992.
“The more I learned about bats, the more interesting I found them,” Long said.
As a field crops and pest management expert for UCCE, Long has worked to boost Californians’ appreciation for bats’ importance in pest control. The state is home to 25 species of bats, seven of which are commonly found in the Central Valley. Bats can consume their body weight or more in insects each night, with a colony of 500 bats eating a grocery bag full of insects from nightfall to dawn. The loss of bats in North America could lead to agricultural losses of more than $3.7 billion per year, according to an analysis published in the journal Science in April 2011. Long has researched bats’ role in reducing Sacramento Valley crop pests.
“We know that bats in the Sacramento Valley feed on insects such as moths, beetles and plant bugs that are often agricultural pests,” wrote Long when the results of her study were published in the January-February 1998 issue of California Agriculture journal. “Potentially, they may help reduce insect infestations in crops by feeding on these pests.”
Long also published a study of bats’ use of constructed bat boxes in the April-June 2006 California Agriculture journal. By evaluating the 186 bat houses in rural areas of California's Central Valley, Long learned that the flying mammals prefer houses mounted on structures such as buildings, those that are shaded or exposed only to morning sun, and within one-quarter mile of water.
Long is an author of the UC publication Songbird, Bat and Owl Boxes, which outlines methods for integrating nest boxes with farm management, provides details on construction and maintenance of nesting boxes, and information on other sources of reliable bat information. The publication includes plans for building a wildlife nesting house.
Naturally, Long sought to share what she knows about bat’s role in the environment with young readers in her fictional but scientifically sound children’s stories.
At the beginning of the book, when Jack falls into the cave, Pinta, the bat, is alarmed. “But as she flew around the cave, her keen ability to echolocate to find her way in the dark, gave her a different picture than she expected. Oh no, a boy, not a monster!” At first, Jack lies on the cave floor knocked out by his injuries. Long writes, “(Pinta) hovered above him, wings stretched more than a foot, beating rapidly but barely making a sound.”
Such tidbits about bats are sprinkled throughout the story. Young readers will be so absorbed in Jack’s journey home, the fate of an escaped jailbird and the search for gold, they won’t realize they are learning about natural science.
Tate Publishing quotes New York Times science journalist Jim Robbins as saying in a review of Gold Fever, “Bats play a little known, but vital role in the world. This book introduces young readers to their world in an engaging and entertaining way.”
Gold Fever is the first in the three-book "Black Rock Desert Adventure Series." Proceeds from the trilogy will go to fund bat conservation programs.
"The UC Cooperative Extension farm advisor system is an integral part of the growth story of the table grape industry in California,” said Kathleen Nave, president of the California Table Grape Commission. "Continuing that growth is critical to the industry but also to the rural communities in which table grapes are grown. With this gift, the University will be able to expand its ability to help growers cope with challenges such as pests, diseases, water quality and quantity, and a host of known and unknown issues that could negatively impact the industry's ability to compete in a worldwide marketplace.”
The California Table Grape Commission-funded position will be headquartered in Tulare. UC ANR will also be hiring a UC Cooperative Extension area viticulture advisor who will be based in Kern County.
"This generous gift by the California Table Grape Commission will enable UC ANR to begin recruitment immediately,” said Barbara Allen-Diaz, University of California vice president for Agriculture and Natural Resources. "As state funding has dramatically decreased in recent years, private-sector support is becoming a critical component of funding important positions essential to the long-term health of agriculture throughout California.”
This new funding model will enable UC ANR to hire outstanding academics to continue to conduct research and deliver new knowledge that is critical to the sustainability of farmers and to California's future.
“Buy firewood from a local source close to your home to prevent the spread of insects and diseases, such as the goldspotted oak borer, sudden oak death and emerald ash borer,” said Tom Scott, a UC Cooperative Extension specialist based at UC Riverside who studies these invasive pests.
“Firewood is one of the least-regulated natural resource industries in California,” said Scott, “but this is a situation where the university can play a critical role in changing behavior through research and education rather than regulation.”
Scott and his UC Cooperative Extension colleagues are working with the U.S. Forest Service, the California Firewood Task Force and other agencies to educate and discourage woodcutters, arborists, firewood dealers and consumers from transporting infested wood.
“Many people don’t realize that firewood can harbor harmful insects and plant pathogens. Moving around infested wood can introduce those pests and pathogens to new areas where they might take hold and could have devastating impacts to trees, our natural resources and local communities,” said Don Owen, California Firewood Task Force chair and CAL FIRE forest pest specialist based in Redding.
“Even wood that looks safe can harbor destructive pests,” cautioned Janice Alexander, UC Cooperative Extension sudden oak death outreach coordinator in Marin County.
For example, female goldspotted oak borers lay eggs in cracks and crevices of oak bark, and the larvae burrow into the cambium of the tree to feed so they may not be visible.
The goldspotted oak borer has killed more than 80,000 oak trees in San Diego County in the last decade and Scott hopes it can be contained in that region. The half-inch-long beetle is native to Arizona but not to California and likely traveled in a load of infested firewood, according to Scott.
In his research, Scott has found outbreaks of goldspotted oak borer 20 miles from the infested area, which leads him to believe movement in firewood is the most likely reason for the beetle leap-frogging miles of healthy oak woodlands to end up in places like La Jolla. In communities where people harvest local trees for firewood, oaks have remained relatively beetle-free, Scott said.
In addition to concealing goldspotted oak borer, firewood may harbor other destructive invasive species such as emerald ash borer or the pathogen that causes sudden oak death. Sudden oak death has killed more than a million oak and tanoak trees in 14 coastal California counties, from Monterey to Humboldt. The highly destructive emerald ash borer has been identified in Michigan, Indiana, Ohio and Illinois, but not California.
“Our best defense against the GSOB outbreak is the enlightened self-interest of Californians purchasing firewood,” Scott added. “If you want to protect the oaks around your house, neighborhood, and nearby woodlands, make sure that you’re not buying wood that could contain these beetles.”
In a broader sense, buy firewood from reputable dealers, from local sources whenever possible – and try to make sure that the wood you buy has been properly seasoned and doesn’t contain pests.
Tips for buying oak firewood
- Don’t buy green firewood from unknown sources, it has the highest chance of containing pests and pathogens.
- Ask where the firewood originated. If it isn’t local, ask what precautions the seller has taken to ensure that the firewood is free of harmful insects and disease or consider buying from another local source.
- Wood should preferably be bark-free, or have been dried and cured for one year prior to movement.
- If you see D-shaped exit holes, be reluctant to buy unless you know the wood has dried for at least a year or longer.
For more information about the pests and diseases that threaten California’s oaks, visit these websites: