- 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
Chicks are typically sold as “day-old” chicks from either an online or local supplier. During those first 4 weeks, chicks are considered “baby chicks”, requiring supplemental heat within the brooder. When raised by a hen, chicks pile under the hen for warmth and venture out more as they grow. Providing a brooder lamp will simulate this and keep your chicks warm without the assistance of a hen. Follow the chart to adequately provide warmth to your chicks. Be careful of fire danger when setting up heat lights.
Typically, the first egg comes at around 18 weeks of age. Once your layers are churning out eggs, you can expect 5-7 eggs per week per layer, or about 250 eggs per year, depending on breed. Productive breeds include Rhode Island Reds (brown eggs), Plymouth Barred Rocks (brown eggs), White Leghorns (white eggs), and Easter Eggers/Ameraucanas (blue/green eggs). Eggs take 24-26 hours to form, with 20 of those hours devoted to shell formation (See How Chickens Make Eggs infographic below).
The Power of Light
Light is the determinant of the start and end of the laying cycle. When daylight hours reach about 12-14 hours per day, a flock will begin to lay. In the North Bay, you can expect this to occur in early spring. The flip side to this coin occurs when daylight shortens in early fall. Egg production significantly declines when daylight hours fall below 12 hours. Chicks purchased in summer may begin laying in fall, resulting in either a shorter laying cycle or lower production. Adding supplemental light to your coop to produce 14 hours of daylight artificially will help to extend the laying season through the winter and increase egg production.
Feed: standard layer mix is fine. Store feed in containers that will discourage scavengers such as mice and rats (e.g. metal can).
Dusting: Chickens love to dust. Dusting is how they clean and with the right ingredients, can prevent ectoparasites. Recommend a dust bathing box (e.g. cat litter box) of diatomaceous earth (DE). Suggested ratio: 1-part DE and 4-parts play sand. This research was done at UCR.
Predators: Recommend having housing that protects your flock from predators, as some predators will try to dig or grab through fencing. Use hardware cloth fencing as the holes in so-called “chicken wire” are too large.
See Backyard Poultry Resources for information to keep your flock happy.
Biosecurity includes any practice that can reduce the risk of introducing disease to a premises. To be effective, biosecurity must be practiced diligently at all times, without exception, by everyone that comes in contact with the premises.
Diseases can strike poultry and pet birds and can spread quickly, causing significant mortality and economic loss to both backyard and commercial operations. Consequently, all bird owners need to be vigilant.
See Biosecurity for information to keep your flock healthy.
Once hens reach about 18 months, the hen often goes through a molt. This is similarly triggered by shorter daylight hours. The hen will stop laying eggs, as energy is diverted to replacing feathers, and begin to lose her feathers. While the scene isn't pretty, this is an important period for hens to refresh feathers before cooler winter months. For backyard flocks, you can try putting the molters (only) back on chick starter diet to supplement their protein during the molting period.
Finally, all good things come to an end. Egg production decreases about 10-20% every year, and, eventually, hens will stop laying entirely. Old hens can act as great fertilizers while still tending to weed and insect control if your coop has room to keep them in the flock. If this is not an option, old hens can be humanely slaughtered and used as meat birds, particularly chicken stew.
If you have additional questions about your new flock, please contactRandi Black: firstname.lastname@example.org.
A wealth of poultry resources can also be found at UCANR's Poultry page.
Here is a summary of some of the work our office is doing during shelter in place.
Fire & Resiliency
UCCE Sonoma is building on the foundational work of other county departments such as Sonoma Water and Permit Sonoma, by providing outreach to private landowners to address forest health, vegetation management and fire fuel reduction.
Lake Sonoma Decision Support System: Development of an online geo spatial reporting tool to help landowners assess:
Match.Graze: development of an online database that connects land owners and grazers.
- Filmed educational videos
- Creating website
- Current status: roll out in early June.
Good Fire Alliance: partnership with Audubon Canyon Ranch to assist landowners in managing fire fuels through prescribed burning on private and publicly owned lands. The following prescribed fires are in the active planning stage:
- 100+ acre burn unit at Cooley Ranch near Lake Sonoma; late May.
- Sonoma Ecology Center is planning a burn at Van Hoosear Wildflower Preserve; late May - early June.
- Bodega Pastures spanning several weekends in October/November.
Resilient Landscapes: Master Gardener collaborative project to:
- Host Firewise webinars
- Develop materials for Fire Safe Sonoma's Living with Fire brochure and webpage resource.
- Post Fire Survival/Mortality: research project to develop a quick and simple post-fire tree survival reference tool to aid with triage of burned landscapes.
- Working with local fire departments to homogenize fire-resilient landscape standards.
Oak Tree Health: organized, hosted and presented:
- California Oak Workshop with science based oak health information. Over 500 participants.
- Sudden Oak Death Blitz pivoted to online, educating and distributing 93 test kits to the public.
Food Systems & Security
- “Stay Home Grow Food” series has reached over 350 people with videos plus resources via an extensive social media campaign.
- Gardener Sense program delivered by video conference to help homeowners reduce water use.
- Master Gardener's are pivoting their classes to webinars.
The value of a strong, connected local food system to sustain the resiliency of our communities has never been more clear.
Coordinating with Sonoma County Food System Alliance and strategizing for a series of video conferences on longer term emergency food response planning & strengthening the local food supply chain looking to local production & distribution as part of meeting food need.
- Meeting on March 23 with over 50 emergency food responders to strategize on coronavirus response.
- Chairing the Community Organizations Active in Disaster (COAD) Food group. Continue to collaborate with the group to meet the needs of emergency food organizations.
- Sonoma County Food Recovery Coalition
UCCE used connections to secure donations of over 12,000 wine boxes to
Redwood Empire Food Bank for boxing and distributing food.
Local Meat Supplies: Mobile Slaughter Unit (MSU)
UCCE is working with local livestock producers in Marin/Sonoma to create a business plan for an MSU which can assist local livestock producers with a local, safe option for processing livestock.
- Applying for USDA grant to assist these producers to determine the functionality of keeping it in production.
- Will develop educational and management strategies to ensure economic security for small-scale livestock producers.
Integrated Pest Management
- Collaborating with UC Davis researchers to continue projects that address soil and fungal pests that shorten the lifespan of vineyards.
Critical research on the newly detected invasive Mediterranean oak borer (pictured) found in valley oak in eastern Sonoma County. Collaborators include Cal Fire, US Forest Service, and CDFA.
4-H youth educational programs have continued to engage youth and adults with online technologies.
- Developed fact sheets to support volunteer educators in delivering online programs available at Youth Development Resources
- Short-term educational programs have been implemented reaching elementary-aged children with science and art content.
- Ongoing programming has been transitioning online focused for teens around college and career readiness (Juntos 4-H) and youth participatory action research.
Annual Sonoma 4-H Open House and ChickenQue transitioned from a full-day chicken BBQ lunch fundraiser to a radiothon.
- Partnered with local radio The Bull 93.7 to do a radiothon.
- The station promoted 4-H with interviews of staff, volunteers, and youth.
- The event also served as a public awareness campaign showcasing the program's legacy helping youth reach their full potential.
Working with local dairy and livestock producers to apply for grants from CDFA to reduce greenhouse gases:
- Alternative Manure Management Program
- Healthy Solis Program
If funded, these grants would bring over $5 million to reduce GHG by 4,154 MTeCO2
Support Local Producers
- Working with local creameries and FEED Sonoma, to develop a dairy CSA box option.
- Revisit the County Lands for Food Production program initiated by UCCE to increase the availability of county owned land to communities, farmers and ranchers.
- Find Local Food & Aid the Community
Providing information and updates.
Coronavirus Resources webpages provides information for agricultural enterprises focusing on financial resources, Ag worker safety and food safety and includes resources for where to find food from local farms and for opportunities to volunteer.
- Author: Lisa A Blecker, coordinator for the UC Pesticide Safety Education Program and Office of Pesticide Information and Coordination
- Author: Whitney Brim-DeForest, UC Cooperative Extension rice advisor in Sutter and Yuba counties
- Author: Katrina Hunter, UC Integrated Pest Management Program pesticide safety writer
- Author: Pamela Kan-Rice, UC ANR Assistant Director, News and Information Outreach
While most Californians are staying home to slow the spread of the novel coronavirus, California farmers, farmworkers and other agricultural professionals are out in the fields and packing houses working to produce food.
With increased demand for personal protective equipment, or PPE, to protect against COVID-19, these essential workers are facing shortages. Agricultural commissioners in 28 counties are hearing from farmers who are having trouble getting PPE for their employees and farmers in another 11 counties who are worried about running out of PPE in the next month or twoaccording to a California Department of Pesticide Regulation survey.
To reduce the spread of COVID-19, workers may wear homemade face coverings, but for applying pesticides, they must wear respirators specified on the pesticide product label, said Whitney Brim-DeForest, UC Cooperative Extension rice advisor.
Pesticide applicators may use gear that is more protective than required by the product label and regulations.
“Although this could change in the days ahead, half-mask and full-mask respirators are more available than disposable N95 respirators for now,” said Lisa Blecker, coordinator for the UC Pesticide Safety Education Program.
Before the pandemic, 10% of N95 respirators from 3M went to health care, but that number is now 90%, the company said in a letter to distributors. This has led to significant backorders of PPE supplies for distributors.
Carl Atwell, president of Gempler's, an online distributor of worker supplies, said that before the crisis, normal lead times for PPE was up to 10 days. He estimated disposable respirators will become available in the fall and other PPE supplies in August.
In the meantime, there is alternative PPE that agricultural professionals can use during the shortage.
Atwell suggests looking for lesser known brands of PPE as opposed to the first tier of choice: “It's sort of like searching for Purell hand sanitizer. Purell brand might be out of stock, but can you find a different disinfectant?
On Gempler's website, the more recognizable Tyvek coverall from Dupont is sold out, however disposable protective clothing is available from other brands. Reusable chemical-resistant clothing is also available as opposed to their disposable counterparts. Supplies in high demand are reusable and disposable nitrile gloves, protective clothing, disposable respirators and certain protective eyewear, such as goggles and face shields.
For workers who will be applying pesticides, Blecker and Brim-DeForest offered some guidelines on how to meet PPE requirements as the shortage continues.
General PPE requirements: “Remember, the label is the law,” said Brim-DeForest. “PPE requirements for agriculture are not being loosened.” The UCCE advisor recommends purchasing only what you need for the season and choosing reusable PPE whenever possible. Growers who have excess supplies of PPE can coordinate with their county agricultural commissioner or UCCE advisor to help other producers in their area.
Respirators: If you can't find the respirator required on the label, Blecker said, “Use an alternative, more-protective respirator. For example, if an N95 is required, you can use a half-mask with N95 particulate filters; these can be stand-alone filters or ones that attach to an organic vapor cartridge. You could also use a different pesticide that doesn't require a respirator. Consult with your PCA (pest control adviser) for options.”
Gloves: Chemical-resistant gloves, usually 14 mil or more in thickness are required for most California pesticide applications and should be worn by mixers, handlers and applicators. If nitrile gloves are not available, viton and laminate gloves are universal chemical-resistant materials for most pesticide labels. If the glove material is specified on the label, that instruction must be followed.
“Disposable gloves less than 14 mil can be worn, but not for more than 15 minutes at a time,” Blecker said. “Farmers should also note that thinner gloves cannot be layered on top of one another.”
Coveralls: Coveralls should be worn when required by the pesticide label or when the signal word is “WARNING” or “DANGER,” or when applying by backpack or airblast. “Coveralls can be made out of high-density polyethylene fibers (Tyvek and other brands), which are disposable, or cotton, which are reusable,” Brim-DeForest said. “If reusable coveralls are worn, the employer must ensure employees are provided clean coveralls.”
Goggles/face shields: Face shields are required for mixing and loading pesticides only if it's stated on the label. “If a face shield is unavailable, a full-face respirator can be used,” Blecker said. “Goggles or protective eyewear should always be worn in California when handling pesticides, regardless of what the label says. The face shield, goggles or safety glasses must provide front, side and brow protection and meet the American National Standards Institute Z87.1 standard for impact resistance.
For more information about PPE, contact your county agricultural commissioner or see the California Department of Pesticide Regulation's posters:
- Author: Karen Giovannini
We are pleased to share our 2019 Annual Report available in two formats! We have our print version and are excited to present our story map version!
Special thanks to Michelle Nozzari for putting together the story map version and Deborah Curle for the print version.