- Author: Michael I Jones
The Mediterranean oak borer (Xyleborus monographus), or MOB, is an invasive ambrosia beetle that was first collected from declining oak trees (Quercus spp.) near Calistoga (Napa County) in 2019 (Fig 1). Subsequently in early 2020, the beetle was detected in the neighboring counties of Lake and Sonoma, and more recently a separate infestation was discovered in suburbs near Sacramento. MOB is native to the Mediterranean regions of Europe, the Middle East, and North Africa and was likely introduced to North America in infested wood material. Within its native range MOB is a pest primarily of dead and dying oaks. In California, MOB has been detected in valley oak (Q. lobata) and blue oak (Q. douglasii). Given the cryptic nature of the insect, the extent of the infestations, and presence of dead trees with evidence of the beetle, the insect has likely been in California for more than five years.
Ambrosia beetles are interesting insects because they carry symbiotic ambrosia fungi which they cultivate along their galleries (boring tunnels) for food. Most ambrosia fungi are weak pathogens (typically only colonizing the tissue near the galleries), but a fungus associated with MOB, Raffaelea montetyi, appears to cause wilt disease in cork oaks in Portugal. This fungus and several others associated with MOB, have been recovered from infested trees in California and research is underway to determine if these ambrosia fungi could cause similar diseases in North American oak species.
MOB appears to initially attack the canopy of host trees where it kills branches, with persistent infestations spreading to the main stem and eventually killing the tree (Fig. 2). The extensive network of MOB galleries can weaken trees and make them more susceptible to failure. Thus far, trees in California with MOB infestations appear to have been stressed by other biotic and abiotic factors prior to MOB colonization, so it is unclear if the insect and its ambrosia fungi can infest and kill healthy trees.
Signs of MOB infested trees are declining canopies, tiny exit holes and boring dust in cracks of the bark, and occasionally sap flux; however, these symptoms could be caused by other boring insects or diseases. The best way to detect MOB infested trees is to observe the pattern of canopy decline. MOB begins by colonizing a large branch in the upper canopy, so newly infested trees will often have one declining branch while the rest of the canopy appears healthy. As the infestation progresses, the entire canopy begins to decline and in some instances, heavily infested branches can produce extensive epicormic sprouting with leaves diminished in size and densely clustered (sometimes referred to as “popcorn foliage”). The most reliable way to confirm MOB is from the architecture of its galleries, which are trellis-like, intersecting, and fan out in a single plane (Fig. 3A). These gallery patterns distinguish it from native Monarthrum spp. of ambrosia beetles, which have galleries branching from a single point and do not intersect neighboring galleries (Fig. 3B). These native beetles will only attack trees that are already dead, dying, or diseased.
Research is currently underway to determine the extent of the two infestations and to find effective management strategies to control MOB. From other similar invasive insects, such as the shot hole borer in southern California, options like chipping (≤1” size), solarization, burning, or burying infested material will likely be crucial in mitigating spread. However, since infestations can be cryptic for several years, there is significant potential for the beetle's range to expand as they can be moved in infested wood and are capable fliers. The best method of control is preventing the movement of the insect and its host material from known infested areas. For more information, please visit: ucanr.edu/sites/mobpc.
If you have a tree that you believe to be infested, please contact the California Department of Food and Agriculture:
- Pest Hotline: 1-800-491-1899
- Report a Pest: cdfa.ca.gov/plant/reportapest/
Michael I. Jones, PhD, UC Cooperative Extension Forest Advisor, Mendocino, Lake, & Sonoma County, mjones@ucanr.edu, (707) 463-4495
- Author: Pamela Kan-Rice
While most Americans choose their Thanksgiving turkeys from the meat department at the local grocery store, Brylee Aubin and Yaxeli Saiz-Tapia can tell you the life histories of their holiday birds. The Sonoma County teenagers raise heritage turkeys together as part of a 4-H youth development project and sell them for Thanksgiving. For the last two years, Yaxeli's older brother Uli has joined the project and, between the three of them, they raised 47 turkeys this year.
The Heritage Turkey Project in Sonoma County has about 15 members of the UC Cooperative Extension's 4-H youth development program and the National FFA Organization growing more than 200 heritage turkeys this year, according to Catherine Thode, who has been leading the project for 15 years.
“Our project leaders are active breeders of heritage turkeys and some of our 4-H and FFA youth are now raising breeding pairs and hatching their own birds,” Thode said. “Each project member raises their small flock of birds on their own property and shoulders the responsibility of providing their feed and care.”
The Heritage Turkey Project promotes the preservation of heritage turkey breeds, sustainable farming and responsible animal husbandry. While raising the animals, the youths learn life skills and earn money for their work.
“The money I raise from raising and selling turkeys goes towards my college fund and to more 4-H projects like market goats or sheep,” said 15-year-old Brylee, who sells her turkeys for $9.50 per pound.
Three years ago, Brylee's neighbor, Yaxeli joined her in the heritage turkey project.
“I have learned how to care for animals, the importance of raising organic and the costs involved,” said Yaxeli, 14. “I have gained a firm understanding of how my birds are raised and processed versus corporate methods. Having the opportunity to participate in this project has strengthened my value for the importance of where my food comes from.”
Consumers benefit by getting turkeys that are farmed organically, fed high-quality grains, and never frozen, said Brylee.
“There are so many benefits to raising these beautiful birds,” said Uli Saiz-Tapia, 17. “First, you learn the cost of running a business, how to reinvest for the next year, the different stages of turkey growth and how to manage issues that arise such as the turkeys fighting, how they react to fluctuating temperatures, how to keep them safe and nourished properly. Learning about the process of getting our turkeys ready to be purchased has really benefitted my understanding of anatomy, the amount of work it takes in preparing them and the importance of not wasting food.”
The group sold out of turkeys in early November.
“Back in March, we really wondered if we should even do the project this year, not knowing what was going to happen with COVID restrictions and the impact on the economy,” Thode said. “We ended up with more project members than we've ever had, and over 200 turkeys to be sold for the Thanksgiving market.”
The 4-H members started the season with more turkeys, but lost some birds to predators. Wildfires seemed to drive more predators to the Sonoma County farms this year, she said.
“Things are fast and furious right now,” Thode said a week before Thanksgiving as the group prepared their turkeys for processing and distribution to people who placed orders. “I'm about to enter the busiest seven days of our year. It will take all weekend to have the birds processed, weighed, labeled. Then, we hunker down to sort and assign turkeys to our customer list.”
While selling turkeys, the group encourages customers to meet the farmers and to visit Livestock Conservancy to look up the history and breed characteristics of the turkey they are purchasing. In past years, some customers have taken photos of themselves with the person who raised their bird.
“We not only have a master list of customers and their desired sizes, but we create a spreadsheet for every project member with a list of the turkeys they've grown that year,” Thode said. “Each turkey is identified in the spring or early summer with a small metal wing band that lists the grower and an individual number for that turkey. When the turkey is sold, the buyer knows which project number grew their turkey, and the variety of turkey that they are purchasing. We think it's important that our customers know this. In fact, when they come to pick up their turkey, they write their check to the actual grower of their turkey.”
Visit Heritage Turkey Project to learn more about the project.
- Author: Steven M. Worker
New Extension Peer Reviewed Curriculum
Through an innovative collaboration with the University of Minnesota Center for Sustainable Polymers, Minnesota, California, and New York 4-H Cooperative Extension educators partnered to develop and pilot youth-driven curricula
Focusing on the use and impacts of plastics and sustainability.
The overarching focus is introducing youth to the prevalence and impact of plastics in everyday life. Experiential activities help youth learn that plastics are versatile materials that come in different shapes, sizes, and exhibit different material properties. Youth learn that there are many advantages of using plastic as they can be lightweight alternatives that can save on fuel and energy. Youth also learn that there are many disadvantages to using plastics, including extracting costs and environmental impacts and a long post-life impact. Youth learn that while some plastics may be recycled and reprocessed, not all plastic makes its way to the recycling bin.
The curricula also introduce youth to the new ways scientists and engineers are working to create, use, and recycle plastics so we can use plastics for their many advantages and lessen their effects on our environment. Some plastics are now designed to biodegrade without polluting the environment and others are created using renewable resources to lessen the dependence on traditional, oil-based plastics.
Sustainable polymers must address the needs of consumers
without damaging our environment, health, or economy.
The curricula were designed to build foundational skills of science and engineering: observation, asking questions and defining problems, planning and carrying out investigations, and communicating. The curricula are intended for delivery in out-of-school time facilitated by an educator (trained volunteers or program staff). Three curricula are available:
- Grades K-2: Focusing on introducing youth to science and engineering as they explore properties of materials and discover how objects are designed with material properties.
- Grades 3-5: Focusing on concepts of: materials; plastics; reduce, use, recycle; and the work of scientists and engineers. Get the curriculum here
- Grades 6-8: Focusing on the prevalence and impact of plastics in everyday life. Youth then become change agents as they discover and work on a plastic sustainability issue that affects their community.
Modules are available for download. Print copies are available from Shop 4-H (only K-2 is available now, grades 3-5 and 6-8 are coming soon).
For more information, please contact Steven M. Worker, PhD, 4-H Youth Development Advisor serving Marin, Sonoma, and Napa counties, smworker@ucanr.edu
- Author: Jeannette E. Warnert
A summer of smoke and ash in many parts of California has raised questions about the safety of produce growing on farms and in the garden, eggs laid by chickens who peck around in ash-laden areas, and remediation needed to safely and effectively grow food in the future.
UC Agriculture and Natural Resources brought together experts who have researched the effects of previous fires' fallout and studied soil contaminants to share their insight in a two-hour webinar now available at Post-fire Soil Safety video.
“The No. 1 health concern during a fire is smoke inhalation, and it's been well documented that wildfire smoke can negatively impact both the heart and the lungs,” said Claire O'Brien, a pharmacology and toxicology doctoral student at UC Davis. “However, the chemicals found in the smoke don't just stay in the air. They can deposit onto plants and into soil and water.”
Although every fire is unique, some generalizations can be drawn from research conducted following previous fires. UC Cooperative Extension food systems advisor Julia Van Soelen Kim detailed a study conducted following the October 2017 wildfires in Sonoma County and across the North Bay.
With the help of UC Master Gardener and community volunteers, the researchers collected over 200 samples of homegrown collard greens, lettuces, kale and chard that were exposed to wildfire smoke and ash. A subset of the samples were analyzed by a private laboratory.
“There was very low concern about chemicals on produce,” Van Soelen Kim said. “No samples had detectable levels of lead, arsenic, mercury or chromium. And that's a huge sigh of relief.” However, analytical results vary by site, site history and by fire event, and few have pre-fire baseline data to compare with.
Van Soelen Kim said basic food-safety practices should be followed when preparing to eat food grown in a home garden, regardless of ash or smoke contamination.
“You should always wash your hands before and after harvesting, and wash your produce in running water to mitigate any kind of potential risk,” she said.
Are backyard chicken eggs safe to eat?
Another study outlined at the webinar used a similar process to determine whether there might be contaminants in the eggs laid by backyard poultry that live and feed in areas exposed to wildfire ash and smoke.
Scientists know from previous research that chickens exposed to lead in their environment can produce eggs with high lead content and that heavy metal content of ash from urban wildfires is higher than from rural wildfire.
“We combined those two pieces of research with what we know that chickens do all day: they peck at the ground for hours on end,” said Todd Kelman, a veterinarian in the School of Veterinary Medicine at UC Davis. “That makes for a pretty good hypothesis that urban wildfire could pose a risk for the production of eggs and poultry that contain heavy metals.”
Kelman and his team put out a call for eggs from backyard poultry and received samples from 344 premises in fire-affected and non-fire-affected areas of California.
Surprisingly, egg samples that contained higher lead levels came from parts of the state that were not directly impacted by ash and smoke.
“Did our data support our hypothesis that proximity to urban wildfire is a driving source for lead in eggs of backyard poultry? The answer is not so much,” Kelman said. “So, is it safe to eat eggs from your backyard poultry? We can't give you a definitive answer to that question. But we do suggest you assess your risk and reduce the risk of contamination.”
Practices that reduce the risk include keeping chickens off the ground, using a chicken feeder that prevents spillage onto the ground and making calcium readily available, for example in the form of oyster shells, because calcium can prevent the absorption of lead. Making sure that chickens are provided uncontaminated water is also an important part of risk reduction.
For confirmation on the safety backyard chickens and their eggs, lab tests for eggs are available for $60 from the California Animal Health and Food Safety Laboratory at UC Davis, or chickens may be submitted to CAHFS for necropsy.
Are soils safe for growing food after a fire?
Fire effects on soil is another consideration in burned areas, said UC Cooperative Extension urban agriculture advisor Rob Bennaton.
“Fires heat topsoil layers. They reduce the amount of living micro-organisms at the site of the burn, and also affect organic matter and nutrients. Ash deposits over time may make soils more alkaline,” he said. “As a result of these combined factors, there are temporary changes in nutrient levels and the capacity for soils to exchange nutrients for optimal plant growth and nutrition.”
With proper land care and management, soils can be remediated over time.
“It won't happen overnight. Soils were developed over millions of years,” he said.
Some ways to improve safety when gardening in fire-affected areas including keeping the soil covered with wood chips or other landscape mulch to reduce airborne soil dust. Use drip irrigation to prevent up splash onto the undersides of growing vegetables. Promote good drainage, especially at the bottom of slopes to prevent the concentration of contaminants.
Lab tests are often needed to determine the soils' post-fire characteristics. “Don't guess, but test,” Bennaton said.
The UC Master Gardener Program can provide technical assistance to help home gardeners find resources for home soil testing, he said.
Resources and information shared during the webinar
Post-fire soil resources and soil testing information
- UCCE publication on Soils in Urban Agriculture with soil testing & sampling information
- The UC ANR Healthy Soils Website, which has many resources worth reviewing.
- Tips for Interpreting Soil Analysis
- UC Master Gardener of Sonoma County 2018 workshop video “Effects of fire on soil”
Post-fire food safety
- Research on produce safety and backyard chicken egg safety after the 2017 wildfires in California is available at Produce Safety after Urban Wildfire. To view a past webinar recording with these research findings, visit Post-fire Food Safety.
- Poultry wildfire resources from the UC Davis School of Veterinary Medicine
- UC Davis School of Veterinary Medicine: "Safety of Backyard Chicken Eggs Post Wildfire" video
- Best Practices for Produce Safety After Fire
- Understanding Risk: A community guide for assessing the potential health impacts of locally grown produce exposed to urban wildfire smoke
Firewise and sustainable home landscaping design in the defensible space zone
- Visit the UC Master Gardener Program of Sonoma County firewise landscaping web page.
- For a recent firewise & sustainable design and maintenance video by the Resilient Landscapes Coalition.
Impact of smoke & ash on plants
- Author: Mimi M Enright
The UC Master Gardener Program of Sonoma County (MGSC) Garden Sense program via its sponsoring organization, Sonoma Water, was named the recipient of the Smart Water Application Technologies (SWAT) Outstanding Public Engagement Award on October 29, 2020.This award recognizes a water provider with a successful program focused on public engagement and education on smart, efficient irrigation technologies and practices. 
The Garden Sense program, initiated in September 2013, is available free of cost to any Sonoma County resident. MGSC presently has 46 trained volunteer Garden Sense consultants who meet with residents in their gardens to evaluate their existing landscaping and irrigation practices, and advise them on how to increase their irrigation efficiency, reduce or remove their lawns, and create climate-appropriate gardens based on their functional needs. Over 900 client consultations have been conducted since the program inception.
Clients who have received a Garden Sense visit are surveyed and asked to rate how helpful the program has been in helping them complete their lawn removal project and/or change their home irrigation practices. The majority of respondents indicated that the visit was either ‘Very helpful' or that they ‘Could not have done it without them'. Conservative estimates of water savings as a result of Garden Sense consultations are equivalent to 26 million gallons of water over the life of the program! One of our clients who was new to the Sonoma County area stated:
“We couldn't have done it without them . . . their advice and expertise was essential to our successfully creating a low water-use landscape. Thank you so much!”
Visit Garden Sense for more information
about the program, or to request a visit.
