The article, “Status and Impact of Walnut Twig Beetle in Urban Forest, Orchard and Native Forest Ecosystems,” published in the Journal of Forestry, updates the spread of the disease, and chronicles the role of the bark beetle, Pityophthorus juglandis, and the canker-producing fungus, Geosmithia morbida, in killing walnut trees, especially black walnuts.
Native to southwestern United States and northern Mexico, the bark beetle, about half the size of a grain of rice, “has invaded urban, orchard and native forest habitats throughout the United States, as well as Italy,” said lead author and forest entomologist Steven Seybold of the Pacific Southwest Research Station, USDA Forest Service, Davis, and a lecturer and researcher with the UC Davis Department of Entomology and Nematology.
Walnut twig beetles (WTB) tunnel into branches and trunks of walnut (Juglans) where they create galleries for mating and reproduction. They carry spores of the fungus into their galleries, and the resulting fungal infection causes formation of cankers, which coalesce and girdle branches and stems.
Between 2005 and 2016, the disease killed nearly 60 percent of the 210 specimens of southern California black walnut mature trees in the USDA Agricultural Research Service's National Clonal Germplasm Repository Juglans Collection near Winters, Seybold said. “This is only an estimate and the true proportion of the mortality is likely much higher, as only six of the 210 trees were rated as having healthy crowns in August 2016."
Seybold estimated that the E Street tree is about 150 years old, "maybe older" and around 50 feet in height. It measures almost 65 inches--or just over five feet--in diameter.
“The walnut twig beetle is also significant because it is the consummate invasive species; it is small enough to travel under the bark of modest-sized pieces of barked wood and it can withstand relatively dry conditions that it might encounter during transit,” Seybold said. “We believe that it has moved from isolated Arizona black walnut trees along creeks and rivers in the desert Southwest to nearly the entire western USA wherever walnut trees of any species have been planted or grew naturally. It has also been transported to Europe and established significant populations in Italy.”
Seybold noted that the disease is “unique because of its multifaceted negative impact on walnut trees involved in landscaping, food production, and forestry. Walnut trees are valuable ecologically and for food and timber, so the walnut twig beetle is a good model in which to study the impact of a bark beetle on forest and agro-ecosystem services.”
Other co-authors are Professor William Klingeman III of the Department of Plant Sciences, University of Tennessee, and forest entomologist Tom Coleman with the USDA Forest Service's Southern Region, Asheville, N.C..
UC Davis doctoral student Jackson Audley of the Seybold lab and Richard Bostock lab (Plant Pathology), contributed photos of dead and dying walnut trees in the Davis area, along with UC Davis doctoral student Corwin Parker and Hishinuma. Audley, who is researching an ensemble of behavioral chemicals that repel the walnut twig beetle from landing on English walnut trees, conducts his research in a commercial orchard near Winters.
“WTB is one of a few invasive bark beetles in North America where expanding distribution and impact have been pronounced enough to affect other species, communities, and ecosystems to the extent that services provided by urban forests, agroecosystems, and wildland areas have been altered,” the co-authors concluded in their paper. “We envision that ecological impacts of WTB will continue to unfold across a wider geographic area to affect various types of key services, i.e., provisioning (e.g., timber and nontimber products); regulating (e.g., air and water quality/quantity, climate regulation); and cultural (e.g., recreation, aesthetics, shade) services.”
Scientists first collected the beetle in North America in 1896 in New Mexico, 1907 in Arizona, 1959 in California, and 1960 in Mexico, but never considered it a major pest of walnut trees until black walnuts began deteriorating and dying in New Mexico in the early 2000s. Walnut tree mortality that occurred in the early 1990s in the Wasatch Mountains of Utah and in the Willamette Valley of Oregon is now attributed to TCD.
“Currently, good cultural practices and sanitation of infested materials are the primary strategies for disease management within orchards and also for prevention of spread of the disease and vector to regions with low rates of infection,” according to the UC Statewide Integrated Pest Management Program (UC IPM)>
UC IPM recommends that trees with less than 50 percent live crown be removed to reduce the buildup of walnut twig beetles and inoculum in the trunk and larger scaffold branches. "Chemical control with either fungicides or insecticides is not recommended for management of thousand cankers disease," UC IPM says.
Lifetime achievement awards went to Frank Zalom, distinguished professor of entomology, UC Davis Department of Entomology and Nematology, who directed the UC Statewide IPM Program (UC IPM) for 16 years; and to Pete Goodell, Cooperative Extension adviser emeritus and UC IPM emeritus.
An international IPM award of recognition went to the European Grapevine Moth Team, headed by Lucia Varela, UC IPM advisor, and including Professor Zalom.
Officials lauded the honorees with these tributes:
"Frank Zalom began his career as an assistant professor for the Department. of Entomology, Fisheries, and Wildlife at University of Minnesota, St. Paul, in 1979. Over the years his career has spanned a wide range of positions and leadership to IPM programs worldwide. In 1986, he became the director of UC Statewide IPM Program and directed it for 16 years to raise the UC IPM program to its 'gold standard' of IPM information in the world. He received a Joint Resolution from the California State Legislature lauding his efforts to advance IPM.
"Frank Zalom's beliefs for IPM are four-fold:
- To solve pest control problems using effective, biologically-based pest management approaches
- To provide IPM leadership at the regional, state, national and international levels
- To provide a vigorous research program in entomology, especially related to IPM and invasive species; and
- To educate a new generation of IPM practitioners through effective undergraduate teaching and graduate student mentoring.
"He believes that advancing the science and implementation of IPM will reduce the impact of pests and pest control on agriculture and the environment. This is critical in California. 'California agriculture is a $42.6 billion industry that generates at least $100 billion in related economic industry,' according to the California Department of Food and Agriculture, and California grows more than a third of the country's vegetables and two-thirds of the nation's fruits and nuts.
"He has pursued these goals through a combination of fundamental studies related to pest biology, physiology, and community ecology; problem-focused, hypothesis-driven management research; and community-oriented extension efforts. His research focuses on exploiting weaknesses in the biology of a pest species and its niche in the agroecosystem or the broader landscape. He builds multidisciplinary research and outreach teams to pursue innovative ideas needed to solve major IPM challenges. His lab's research has addressed seventeen invasive species introductions: among them southern green stink bug, silverleaf whitefly, glassy-winged sharpshooter, olive fly, invasive salt cedar, light brown apple moth, spotted wing drosophila, and most recently European grape vine moth, brown marmorated stink bug and Bagrada bug." (See more about his career on UC Davis Depatment of Entomology and Nematology website.)
"Early in his career, Goodell focused on reduction of use of broad-spectrum insecticides and development of easy to implement scouting methods. For example, he was instrumental in the development and adoption of time saving presence/absence sampling for mites in cotton. Mid-career, Goodell helped to pioneer year-round IPM programs because of his collaborations with the Natural Resources Conservation Service. Year-round IPM programs describe pest management activities important for that crop stage or season and addresses key pest management for multiple pests. This departed from addressing one pest to a more holistic program focused on prevention and decision-making. UC IPM now has year-round programs for 25 crops and recently expanded the concept to develop seasonal landscape IPM checklists for four eco-regions in California. Later, Goodell was one of the first to incorporate social science concepts regarding the drivers of change in behavior into IPM learning and adoption. He was a founding member of the group that developed the Toolkit for Assessing IPM Outcomes and Impacts.
"To end his career, Goodell is leading a California Department of Pesticide Regulation (DPR) funded project to host discussions on pests, pesticides, and IPM broadly throughout California. At the foundation for this project, it assumes that pests are part of every persons' experience and pest management is necessary to protect society. The hope is the project will generate a consensus statement about risks from pests and pesticides and provide direction for the future of IPM in California. That will be an incredible final accomplishment for Dr. Goodell's career and for IPM everywhere." (See more about his career on the UC ANR website.)
European Grapevine Moth Team
"The European Grapevine Moth Team was selected for an IPM Team Award for achieving the eradication of European grapevine moth only six years after its discovery in 2009. Team members helped growers in infested counties to monitor the pest and apply control measures on a timely basis. The team's research and extension efforts helped growers avoid losses to the pest every year until it was finally eradicated in 2016.
"In September 2009, European grapevine moth (EGVM) was detected in grapes in Napa County and confirmed by USDA on Oct.7, 2009. European grapevine moth larvae bore holes into grape berries directly damaging the fruit and allowing entry of fungal pathogens. The European Grapevine Moth Team, achieved the eradication of European grapevine moth only six years after its discovery.
"The team mounted a multi-pronged program to study the biology and life cycle under California conditions, assisted and informed growers to monitor and control this pest, and addressed regulatory questions regarding detection and delimitation. The team designed and conducted 15 trials to evaluate winter mortality factors, validate monitoring tools, determine the host range, evaluate organic and conventional insecticides, and study larval mortality during the winemaking process."
The European Grapevine Moth Team includes Lucia Varela, UC IPM advisor for the North Coast; Frank Zalom,IPM specialist and distinguished professor of entomology, UC Davis Department of Entomology and Nematology; Monica Cooper, UC Cooperative Extension viticulture adviser in Napa County; Walter Bentley, UC IPM entomologist emeritus; Larry Bettiga, UC Cooperative Extension adviser in Monterey County; Kent Daane, UC Cooperative Extension specialist in UC Berkeley Department of Environmental Science, Policy and Management; Rhonda Smith, UC Cooperative Extension adviser in Sonoma County; Robert VanSteenwyk, UC Cooperative Extension specialist in UC Berkeley's Department of Environmental Science, Policy and Management; and Joyce Strand, UC Davis IPM Academic Coordinator emeritus.
Officials praised Zalom for his outstanding leadership and public service at the regional, state, national and international levels; his stellar academic accomplishments in agricultural sustainability and IPM; his strong work ethic, service, courage and integrity, all driven by “his insatiable curiosity and passion to solve problems in the agricultural landscape”; and his tireless advocacy for IPM as THE way to address pest concerns in a sustainable, economical and environmentally acceptable manner.
“Dr. Zalom continues to advance the science and implementation of IPM,” said Steve Nadler, professor and chair of the UC Davis Department of Entomology and Nematology. “His integrity, service and respect for all are legendary.”
Zalom, who holds a doctorate in entomology from UC Davis, teaches arthropod pest management, targets pests using IPM methods, and develops major agricultural IPM programs for California's specialty crops.
Zalom is a past president of the 7000-member Entomological Society of America; co-founder of the International IPM symposia; and for 16 years, directed the University of California Statewide IPM Program, considered “the gold standard” of IPM programs.
At the Baltimore seminar, Zalom will deliver a presentation on “The ‘I' in IPM: Reflections on the International IPM Symposium and Evolution of the IPM Paradigm.” He will reflect on his 16 years co-chairing the Association of Public and Land-Grant Universities' National IPM Committee, the committee that launched the symposia. Zalom also played a role in organizing the first four IPM Symposia.
The only other lifetime achievement award recipient this year also has a UC connection: Peter Goodell, UC IPM advisor emeritus, affiliated with the Kearney Agricultural Research and Extension Center, and a longtime friend and colleague of Zalom.
Zalom's 16 years at the helm of the UC IPM program set the standard, nationally and globally, for subsequent IPM programs. He established a statewide, interdisciplinary IPM team of Cooperative Extension farm advisors, and oversaw development of the website's online degree-day tool, and the database of degree-day models that remains widely used by California's county-based extension staff and crop consultants.
“Advancing the science and implementation of IPM will reduce the impact of pests and pest control on agriculture and the environment,” Zalom said. “This is critical in California, where we grow more than a third of our nation's vegetables and two-thirds of our nation's fruits and nuts. California agriculture is a $42.6 billion industry that generates at least $100 billion in related economic industry.”
Zalom interacts broadly with research colleagues, extension educators, growers, consultants, environmental groups, and public agency personnel throughout the state, nation and world to advance the science and use of IPM. He has served on scores of national ad hoc committees of agencies and organizations that shaped IPM policy and directions. He was recently appointed to a new Council for Agricultural Science and Technology (CAST) task force that will produce a white paper on behalf of the organization on Integrated Pest Management. He previously served on the task force for the CAST Issue Paper, “Feasibility of Prescription Pesticide Use in the United States."
Zalom's professional goals are four-fold (1) to solve pest problems using effective, biologically based pest management approaches; (2) to provide IPM leadership at the regional, state, national and international levels, (3) to maintain a vigorous cutting edge research program in entomology, especially related to IPM and invasive species; and (4) to educate a new generation of IPM practitioners through effective undergraduate teaching and graduate student mentoring.
Zalom has pursued his goals through a combination of fundamental studies related to pest biology, physiology, and community ecology; problem-focused, hypothesis-driven management research; and community-oriented extension efforts. “I focus my research on exploiting weaknesses in the biology of a pest species and its niche in the agroecosystem or the broader landscape,” Zalom said.
- Appointed the first Editorial Board chair of ESA's new Journal of Integrated Pest Management.
- Founding member of the steering committee for the USDA-NIFA Pest Management Information Platform for Extension (ipmPIPE), an effort intended to assess risk of disease and insect outbreaks.
- Co-principal investigator of the USDA grant for $3.49 million that originally funded the Western IPM Center, located at UC Davis
- Numerous leadership roles in the Entomological Society of America (ESA), including president in 2014, member of ESA's presidential line for four years and Governing Board member for four years. He also served as the president of the Entomological Foundation and first chair of ESA's new Science Policy Committee.
- Author of more than 350 peer-reviewed journal articles, book chapters, and books, and has served as major professor for 12 Ph.D. students and seven master's students.
- Recipient of multiple awards at UC Davis including one for his outstanding mentoring, of women graduate students and post-doctoral scholars.
- Co-chair of the International Entomology Leadership Summit in 2016 in Orlando,Fla.
Zalom is a fellow of the California Academy of Sciences, Entomological Society of America, American Association for the Advancement of Science, and Royal Entomological Society (London). Previous IPM awards include the Entomological Foundation's IPM Team Award and Excellence in IPM Award, and the Perry Adkisson Distinguished Speaker Award from Texas A&M University. He is the only entomologist to be awarded the BY Morrison Memorial Medal for horticultural research, presented by the Agricultural Research Service of the U.S. Department of Agriculture, and the American Society for Horticultural Science.
Zalom, who joined the UC Davis faculty in 1980, shortly after receiving his doctorate of entomology in 1978, earned both his bachelor's and master's degrees in zoology and ecology from Arizona State University, Tempe.
Saturday, Aug. 20, is National Honey Bee Day. Observed on the third Saturday every August, this day educates people about the importance of honey bees and promotes the work of beekeepers.
Various insects, birds, and other animals pollinate plants. Bees, especially honey bees, are the most vital for pollinating food crops. Many California crops rely on bees to pollinate their flowers and ensure a good yield of seeds, fruit, and nuts. Pesticides, especially insecticides, can harm bees if they are applied or allowed to drift to plants that are flowering.
Our mission at the University of California Agricultural and Natural Resources (UC ANR), Statewide Integrated Pest Management Program (UC IPM) is to protect the environment by reducing risks caused by pest management practices. UC IPM developed Bee Precaution Pesticide Ratings to help pest managers make an informed decision about how to protect bees when choosing or applying pesticides.
The bee precaution ratings are based on the reported effects of a pesticide's active ingredient on adult honey bees or their brood. You can find and compare ratings for active ingredients including acaricides (miticides), bactericides, fungicides, herbicides, and insecticides.
Ratings fall into three categories. Red, or rated I, pesticides should not be applied or allowed to drift to plants that are flowering. Plants include the crop AND nearby weeds. Yellow, or rated II, pesticides should not be applied or allowed to drift to plants that are flowering, except when the application is made between sunset and midnight if allowed by the pesticide label and regulations. Finally, green, or rated III, pesticides have no bee precautions, except when required by the pesticide label or regulations.
It is important to note that the bee precaution pesticide ratings are not the pollinator protection statements on the pesticide label.
Each crop in the UC Pest Management Guidelines has links to the bee precaution ratings and provides guidance on how to reduce bee poisoning from pesticides. For more information on protecting bees from pesticides, see UC IPM's Protecting Natural Enemies and Pollinators, and use the Bee Precaution Pesticide Ratings.
The European Grapevine Moth Team received the 2016 "distinguished service award for outstanding team." The members "coordinated a program that saved the wine and table grape industries from economic disaster caused by an invasive insect,” according to UC ANR Vice President Glenda Humiston.
“The impact of the team's work has reduced quarantines for European grapevine moth from 10 counties in 2010 to a portion of one county at the end of 2015 and no moths have been trapped in the last remaining quarantine zone since 2013," Humiston noted. "If no European grapevine moths are trapped in this zone in 2016, the last remaining quarantine for the pest will be lifted."
Humiston called the team "an excellent example of UC ANR working with government and industry partners under the Endemic and Invasive Pests and Diseases Strategic Initiative.”
Zalom, a past president of the 7000-member Entomological Society of America (ESA) and a past director of the UC Statewide Integrated Pest Management (UC IPM), is the lead author of the European Grapevine Moth provisional guidelines page on the UC IPM website. Co-authors are Lucia Varela, UC Cooperative Extension, North Coast and Mountain Region, and Monica Cooper, UC Cooperative Extension, Napa County.
In addition to Zalom, Varela and Cooper, the European Grapevine Moth Team included:
- Walter Bentley, UC IPM entomologist emeritus
- Larry Bettiga, UC Cooperative Extension advisor in Monterey County
- Kent Daane, UC Cooperative Extension specialist in the UC Berkeley Department of Environmental Science, Policy and Management (ESPM)
- Rhonda Smith, UC Cooperative Extension advisor in Napa County
- Robert Van Steenwyk, UC Cooperative Extension specialist in the UC Berkeley ESPM
- Joyce Strand, UC IPM academic coordinator emeritus
The distinguished service awards are given biennially for outstanding contributions to the teaching, research and public service mission of UC ANR.
The European Grapevine Moth is a serious pest of grapes; it causes significant damage to the flowers and berries. Native to Southern Italy, it was first reported in the United States in Napa County vineyards in October 2009. It is now found throughout Europe, North and West Africa, the Middle East, and eastern Russia.
(Editor's Note: See other UC ANR awards presented)