- Author: Cindy Kron
Invasive tree-of-heaven is a preferred host for two invasive insect pests that cause economic damage in California agricultural crops
It is not uncommon for commercial agriculture to share a common boundary with riparian, forested or urban areas in California. Some pest species thrive in these border areas and serve as a source of insect pest pressure on neighboring commercial crops. Invasive species that find preferred hosts in these border areas can be especially problematic in that their new environment lacks the predators from their native habitat that would normally suppress and keep their population manageable. This uncontrolled population growth can result in significant economic damage to nearby commercial crops.
The tree-of-heaven (TOH), Ailanthus altissima, is an invasive tree that has been documented in 45 states including California. This deciduous tree can be found in agricultural, urban, riparian and disturbed forested areas (Fig. 1A, 1B). This tree serves as a preferred host of two invasive species: the brown marmorated stink bug (BMSB), Halyomorpha halys, and the spotted lanternfly (SLF), Lycorma delicatula.
In California, BMSB is established in 16 counties and detected in 23 additional counties. The brown marmorated stink bug has over 170 host species (fruit, nuts, vegetables, and ornamentals) including the following agricultural crops: grape, pear, apple, stone fruit, citrus, blueberry, raspberry, blackberry, fig, almond, hazelnut, sunflower, sweet corn, soybean, okra, bell pepper, green bean, tomato, and eggplant. To date, in California, BMSB has been observed causing damage in commercially grown almond, apple, peach, and pear orchards.
The SLF has been recorded in 6 East Coast states but has not yet been documented in California. This insect lays eggs on plant and nonplant items such as stones, pallets, outdoor furniture, railway cars, firewood, and vehicles, which contributes to their wide dispersal ability and their likelihood of unintentional introduction into California. The SLF has at least 40 host species (fruit, nuts, ornamentals, and woody trees) found in North America including the following agricultural crops: grape, stone fruits, apple, blueberry, fig, hops, walnut, and almond.
BMSB and SLF share some similarities. Both are native to China, introduced into the U.S. via Pennsylvania, cause economic damage in a range of commercial crops found in California, and aggregate in large numbers. The tree-of-heaven is a preferred host.
In addition to supporting the growth of economically damaging insect pests, the tree-of-heaven has its own impacts on the ecology of areas where they establish. The tree-of-heaven competes with native plants and trees by releasing allelopathic chemicals that prevent the establishment and inhibit the growth of native trees nearby (Fig. 1C). The tree has a rapid growth rate of 3 to 6 feet a year and is able to start bearing seeds within 2 to 3 years. Female trees can produce more than 300,000 seeds (Fig. 2A) that are easily dispersed by the wind allowing for new trees to establish some distance from the parent tree. Established trees can also spread by sending up root suckers up to 50 feet from the parent tree. In addition, small root fragments can also generate new shoots. An injured or cut tree-of-heaven responds by producing numerous root sprouts that allows the tree to spread prolifically and complicates efforts to remove the invasive tree. The tree-of-heaven is a high pollen producer aggravating those with allergies. Direct contact can cause skin irritation and, in rare cases, inflammation of the heart muscle has been documented from exposure to sap through broken skin. These features of tree-of-heaven fuels its ability to invade new environments and makes it very difficult to remove after it has become established.
Being that the tree-of-heaven is invasive and also supports two invasive insect pests that are known to cause economic damage in a range of commercial agriculture crops grown in California, it is important for the agriculture industry to become familiar with how to identify the tree-of-heaven. This knowledge can be used to increase the awareness of the proximity of these trees to host crops that you work with, manage or own. Calculated management decisions can then be made from this information.
The tree-of-heaven is similar in appearance and can easily be confused with a handful of native tree species: black walnut (Juglans nigra), winged/shining sumac (Rhus copallina), ash (Fraxinus spp.), staghorn sumac (Rhus typhina) and butternut walnut (Juglans cinerea). Young tree-of-heaven have greenish smooth bark (Fig. 3A) that turns a greyish-brown in older trees resembling the skin of a cantaloupe (Fig. 3B). Leaves have a central stem with 10 to 40 leaflets attached on each side by a short petiole (Fig. 4A). A V-shaped or heart-shaped scar is noticeable when a leaf is broken off of the main stem (Fig. 4B). The margins of the leaflets are smooth with one to two bumps called glandular teeth that protrude at the base of each leaflet near the petiole (Fig. 4C). A corresponding gland is located on the underside of the leaflet where the glandular teeth are located (Fig. 4D). A strong odor described as cat urine, rancid cashews or burnt peanut butter is given off when the leaves or stems are crushed. Twigs break easily exposing a brown spongy pith. Tree-of-heaven are dioecious with separate male and female trees. Female trees produce red, yellow and green “samaras” that each contain one seed covered by a winged and papery tissue used in wind dispersal (Fig. 2B).
Agricultural land and nearby areas should be inspected for existing tree-of-heaven stands. There are different strategies that can be followed upon identifying this tree in or near farmed land. The first strategy is to use the tree-of-heaven as a sentinel tree that is visually inspected periodically for the presence of BMSB and SLF life stages during the growing season. This would be an easy and ideal option if either invasive pest is not reported in your county or nearby counties. Early detection can help prevent establishment in your county and the economic damage that these invasive species cause in commercial crops. Any sightings or insect samples should be submitted to your local county agricultural commissioner's office.
A second strategy could be used if detections of either invasive species have occurred in your county or local area. Traps for BMSB monitoring can be deployed using a double-sided sticky panel with a dual lure and placed near the tree-of-heaven. If SLF were to arrive in California, brown sticky bands wrapped around the trunks of tree-of-heaven can capture the immature stages as they engage in their typical behavior of walking up the tree. Trap finds can alert growers of an invasive species presence in an agricultural field and treatment decisions can then be made.
A third strategy would be to remove tree-of-heaven, but this comes with a warning: mowing or cutting, by themselves, are ineffective and can cause the tree to spread prolifically. Care needs to be taken when deciding to remove tree-of-heaven since a cut tree responds by sending up numerous root sprouts up to 50 feet from the parent tree. Timing of treatment and commitment to follow up with subsequent treatments the following year are crucial for success. If tree removal is the decision made, the root system should be targeted with a systemic herbicide 30 days before cutting the trees and the application needs to be made between July and mid-October when carbohydrates are being allocated to the root system. If an herbicide is applied outside of this range, the application would likely be ineffective due to targeting the above ground growth and not the root system. Gloves, long-sleeved shirts and pants should be worn during tree removal to prevent the contact of tree parts and sap with the skin. Follow-up monitoring is needed to determine the need and timing of additional treatment applications./h2>
Smith described as icon and heroine for work in advancing wine grape production
A scientist first and foremost, Rhonda steadily emerged as Sonoma County's resident expert on all things wine grape during her nearly 34 years as the viticulture advisor for the University of California Cooperative Extension. Over the decades, she used her scientific know-how, meticulous research methodology and incredible work ethic to advance wine grape production in Sonoma County.
She cultivated real working relationships with growers and vineyard managers during her time setting up field trials and collecting data in vineyards throughout Sonoma County. As the years rolled by, she earned the respect and admiration of grape growers who wonder what they will do without her as she leaves her longtime post and heads into retirement.
“Rhonda Smith became a true icon in Sonoma County viticulture for her timely research and her effective way of communicating valuable information to the wine grape industry,” said grower Bob Dempel of Santa Rosa.
Tito and Janet Sasaki who farm wine grapes in the Sonoma Valley are among the growers who have benefited from Rhonda Smith's dedication to the wine grape industry. The Sasakis said Rhonda is continually studying the latest developments in viticulture science but is always ready to be in the field to help growers – often at a moment's notice when a new problem crops up.
“Rhonda Smith is the quiet heroine of the vineyards in Sonoma County. She has been the family physician of Sonoma County vines for more than three decades,” said Tito Sasaki, past president of Sonoma County Farm Bureau and a longtime agriculture industry leader. He marvels at how Rhonda has managed the challenges of raising a family while coming to the rescue of growers facing problems like red blotch virus, vine mealybug, Pierce's disease and many other threats.
“Her serene and relaxed demeanor conceals the rock-solid strength of her dedication to others,” Tito said.
Said Janet Sasaki, “Rhonda is the hardest working person I know. My friends and I have been working with her since 1989. No vineyard is too small for her to take an interest in the problem. She is very respected by everyone in the wine grape industry.”
For her part, Rhonda, who is 66 and the mother of two grown children, said she has been fortunate to work in a field she loves, particularly, being able to focus so much of her time and energy on plant pathology, which has intrigued her since her days as a student at the University of California, Davis. She was inspired by professors and Cooperative Extension farm advisors who used scientific research to find ways to combat the diseases that were impacting agriculture and causing economic losses to farmers.
Becoming the viticulture advisor in Sonoma County gave her the opportunity to do the research she loved while providing the best possible opportunities for growers to thrive and produce the world class wines that have made Sonoma County famous. She said her goal has always been to assist the industry in successfully navigating the delicate balance between grape quality and economically acceptable crop yields – the essential combination to prosper as a premium grower of wine grapes.
“It's been fun and rewarding to be part of the Sonoma County wine industry for so many years,” said Rhonda, a resident of Windsor. Over the years she has been recognized with awards and accolades for her many contributions. In 2008 the Harvest Fair board of directors named her “Friend of Agriculture,” noting her hard work “to keep agriculture part of the Sonoma County landscape.”
Rhonda arrived in Sonoma County in 1986 to fill the UCCE viticulture advisor position held for many years by Robert Sisson, who had helped orchestrate Sonoma County's transition to premium varietals like chardonnay and cabernet sauvignon. It was a move that took Sonoma County from jug wine producer to a celebrated player on the world's wine stage.
Realizing the importance of maintaining quality and economic viability for Sonoma County's most important farming endeavor, Rhonda rolled up her sleeves and plunged into research and grower outreach to assist the viticulture industry as it faced continued new threats.
Shortly before starting as viticulture advisor, there was a crisis: vineyards throughout Sonoma and Napa counties were in decline, displaying lackluster vigor and sharp drops in yields. The culprit was phylloxera, a tiny insect that feeds on grapevine roots.
At that time, more than half the vineyard acreage in Sonoma and Napa counties was planted on a rootstock that had become susceptible to the insect pest. As a result, the majority of the vineyard acreage had to be replanted once severely infested with phylloxera.
Growers desperately needed a path forward. Rhonda and other scientists from UC Davis launched trials to evaluate the performance of alternative rootstocks for vineyards in the North Coast counties.
Through her rootstock trials, Rhonda was able to inform growers of the suitability of specific rootstocks in sites with heavy, cracking clay, wet soil conditions and high nematode populations.
Stephanie Larson, who is the director of UCCE in Sonoma County, said Rhonda Smith's targeted work on so many important issues epitomizes what a UCCE advisor should be – diligent and dedicated to finding solutions to growers' problems and channeling information and research from the University to the field. She said Rhonda's work spanned the spectrum from identifying the best rootstocks to coping with powdery mildew.
“Rhonda was a solid advisor who was extremely dedicated to the wine grape industry. She held UCCE Sonoma County Grape Day each year, without exception since 1987. Grape Day provided growers the most current information on issues such as pests, water, diseases, clones and rootstocks,” said Larson.
For 20 years Rhonda also coordinated the Sonoma County Vineyard Technical Group's nine monthly programs each year, working collaboratively with grower-members to select topics and speakers – including those from out of state - to bring research-based information that addressed farming practices and pest management applicable to the local industry.
“Throughout her career, Rhonda collaborated with state and local regulatory and resource agencies to provide expertise on issues that directly affect wine grape production,” Larson said.
Larson said Rhonda's retirement leaves a huge gap in viticulture knowledge and expertise for the industry. Unfortunately, she said, because of the state's current budget crisis, the UC Division of Agriculture and Natural Resources will not be filling Rhonda's position. But Larson said the University would entertain a discussion with the wine industry to hire a new viticulture advisor if the industry would fund half the cost of the position. She said there must be a five-year commitment for the funding.
Rhonda, who came from a military family, grew up in El Dorado Hills outside of Sacramento. She didn't have a farming background but early on knew she wanted to work outside, not in an office cubicle, after spending time at her uncle's walnut and hog ranch in Galt.
She went to UC Davis and in 1977 earned a bachelor of science degree in plant science, with an emphasis in plant pathology. In 1983 she completed a master's degree from Davis in horticulture, with an emphasis in viticulture.
Before taking the viticulture position in Sonoma County, she worked as a research associate for UC Davis, UCCE and the Department of Food and Agriculture in various parts of California.
Rhonda said her work in Sonoma County was more expansive and productive because of the tremendous cooperation of growers, vineyard managers and wine industry executives who provided vineyards and support for the field trials she conducted. She worked with dozens of vineyard industry professionals during her long career, often, bonding over mutual interests in chardonnay clones or vexed by the vagaries of Pierce's disease, caused by a bacterium spread by the blue-green sharpshooter.
Mark Lingenfelder, who was at Chalk Hill Estate Winery for many years, worked with Rhonda on a number of projects including chardonnay clonal studies and trials investigating the efficacy of a plant growth regulator to improve fruit set. Lingenfelder said because of Rhonda's expertise and professionalism it was a pleasure cooperating and collaborating on research trials that yielded valuable information that was shared with the viticulture industry.
“I was always amazed by Rhonda's energy, persistence and meticulous attention to detail. But she was not only a dedicated and tireless researcher. She was also a friendly, knowledgeable and patient advisor who was always incredibly generous with her time whenever I turned to her for advice,” said Lingenfelder. “We've had some great long conversations.”
Dana Grande, grower relations manager at Jordan Vineyard & Winery in Healdsburg, said she first met Rhonda Smith in 1994, a time when there were few women working in the viticulture industry.
“At that time, you could count the number of women in Sonoma County viticulture on one hand. Our relationship has always been one of mentorship – her to me - and it encompassed not only viticulture expertise, but how to carefully balance the career/mom life,” said Grande.
From 2002 to 2008 Grande worked with Rhonda on a study of berry shrivel in a cabernet sauvignon block, which was known as “Rhonda's Rows,” at Jordan. The collaboration forged a long, lasting relationship and mutual respect between the two viticulture professionals.
“I can't imagine what Sonoma County viticulture will look like without Rhonda Smith,” said Grande. “I and many others have relied on her advice, experience, and expertise for decades.”
In retirement, Rhonda plans to take a deep breath and then catch up on projects around the house and do some traveling. She will also have more time to spend with husband Dana and her grown children. Her daughter Emma, 29, is a US Air Force Captain and a Medical ICU nurse now preparing for her second deployment to the Middle East. Son Charles, 26, recently graduated from Chico State University with a degree in criminal justice and is seeking a job in law enforcement.
And at some point, Rhonda plans to sit back and reflect on her long and fruitful career while savoring Sonoma County wines.
Like many who appreciate wine, Rhonda is intrigued by the sensory elegance of what wine grapes become when entrusted to the hands of a masterful winemaker. “I appreciate the growers who provide wineries with the best fruit possible by making critical farming decisions driven by experience, knowledge and research based information.”
“Sonoma County has an ideal climate for growing wine grapes, but it is up to growers to establish then farm a vineyard with a balanced crop load, adequate soil moisture and canopies that maximize desired fruit composition. All that while managing pests, diseases and labor shortages.
I feel honored to have been able to work with
the people who are in this industry.”
Written by Tim Tesconi
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.