- Contact: Mary Louise Flint
“The disease has killed thousands of black walnut trees in California’s landscape and is threatening commercial walnut trees as well,” said Mary Louise Flint, UC Cooperative Extension specialist in the Department of Entomology at UC Davis and UC Statewide IPM Program.
Thousand cankers disease has now moved into the eastern U.S., where it threatens valuable stands of black walnut timber east of the Mississippi. Once in trees, the beetle and fungus cause gradual decline and eventual death by killing the vital phloem tissue beneath the bark.
The guidelines and trapping methods were developed by a team of entomologists from UC Davis and the USDA Forest Service Pacific Southwest Research Station in Davis. In 2010 and 2011, the scientific team discovered and patented an aggregation pheromone for the beetle and conducted scientific trials in northern California.
Late in the summer of 2011, they demonstrated the efficacy of the pheromone as a flight trap bait for detecting new populations of the beetle in Tennessee, Virginia and Utah. The demonstration-research project was extended to Pennsylvania in 2012. The bait lures both male and female beetles into a small plastic funnel trap. The team worked with a commercial partner, Contech Enterprises, Inc., to develop the technology.
As the eastern black walnut resource is valued at over $500 billion, the stakes are high for containing thousand cankers disease if it is introduced into key timber-producing states like Indiana and Missouri.
The study team is also using the traps and pheromone in research in California to learn more about biology and potential management strategies for the beetle in commercial walnut orchards and wildland areas.
The trapping guidelines are presented in a full-length document with color photographs and details on identifying the beetle, a short version for use in the field, and two video clips that demonstrate how to set up and service the traps. Find them at http://www.ipm.ucdavis.edu/thousandcankers.
In addition to Flint, members of the UC Davis and USDA scientific team and authors of guidelines are Steven J. Seybold, insect chemical ecologist, USDA Forest Service, based at Pacific Southwest Research Station in Davis; Paul L. Dallara, postdoctoral research scientist in the Department of Entomology at UC Davis; and Stacy M. Hishinuma, graduate student, Department of Entomology at UC Davis.
- Author: Jeannette E. Warnert
“I started and just kept going,” said Charlie Summers, a research entomologist who was first affiliated with UC Berkeley and later affiliated with UC Davis. Summers ends a 42-year stretch at Kearney when he retires June 30.
Summers grew up on a family farm in Utah and always knew he wanted a career in agriculture. He said he decided at age 12 to go to college, “when I was at the wrong end of a short-handled hoe.”
Summers earned bachelor’s and master’s degrees in zoology and entomology respectively at Utah State University in Logan, Utah, and a doctorate degree in entomology at Cornell in 1970, the same year he started at Kearney.
“The job at Kearney was an absolutely perfect fit for me,” Summers said. “It was a dream job. I look forward to coming to work every morning and would sometimes shake my fist at the sun going down at night. I’ve loved every minute I’ve been here.”
Summers studied a wide range of pest problems in field and vegetable crops. He developed economic thresholds for more than a dozen pests and management strategies for equally as many crops. Among the most challenging pests was the alfalfa weevil, he said. It has been particularly unresponsive to biological control and host plant resistance.
“It is one of the insects that has defied everything we’ve thrown at it except pesticides,” Summers said.
Silverleaf whitefly also posed a tremendous challenge during his career. Silverleaf whitefly was first found in the United States in Florida poinsettia crops during the mid-1980s. Eventually it made its way to a wide range of crops in California, resulting in severe economic losses to growers. Heavy applications of traditional chemicals needed to control the pest caused growers’ costs to increase. The production of some crops ceased altogether because of the extent of silverleaf whitefly damage.
In time, Summers and his colleagues developed a protocol for monitoring and managing the silverleaf whitefly. Light populations are controlled by native and introduced parasites and predators. More severe infestations must still be treated with pesticides.
Another major challenge was the corn leafhopper. The pest first made its way to California in the early 1940s, but didn’t become a serious problem until the end of the 1990s, when it was found to transmit corn stunt disease.
“Corn stunt disease caused plants to form few or no ears of corn. Some farmers’ yields were cut in half,” Summers said. “We worked out a strategy for scheduling planting to avoid the most serious damage. That’s worked out well for growers.”
Crops grown on silver mulch produced significantly higher yields of marketable fruit than did those grown on bare soil, the researchers concluded. Reflective mulch has been used by organic and conventional farmers up and down the valley and in Southern California to grow vegetables. Home gardeners have also applied these research results to garden beds by using aluminum foil as mulch.
Although Summers did not technically have a Cooperative Extension component to his position – he was among the last scientists hired to devote 100 percent of their time to research – Summers made it a point to work closely with farm advisors and specialists to convey research results to farmers.
“Extension work has been one of the most enjoyable things I’ve done,” he said. “I’ve worked with farm advisors on research projects, farm calls and given hundreds and hundreds of extension talks at their grower meetings.”
Summers has also authored more than 200 articles, book chapters and research papers, most of them peer reviewed.
Over the years, Summers said, the objective of his job – to help farmers develop successful pest management strategies – stayed the same, but technological advances dramatically changed the way he did his work.
“We’ve had the advent of computer technology, the use of mathematical models, work that can now be done at the DNA level. It’s put a whole new face on our ability to do research,” he said.
Nevertheless, he said, nothing can replace what he considers the essence of the Agricultural Experiment Station model: to personally assist growers.
“To me that’s the most important job we performed,” Summers said. “I hope this work continues.”
In retirement, Summers plans to move back to Utah to live near his sister and nephews and spend time pursuing his favorite pastime, fly fishing.
“I’ll be living 15 minutes from the Wasatch Mountains,” Summers said. “There’s a lot of good fishing there.”
- Author: Sarah Yang | Media Relations scyang@berkeley.edu, (510) 643-7741
By the end of the century, almost all of North America and most of Europe is projected to see a jump in the frequency of wildfires, primarily because of increasing temperature trends. At the same time, fire activity could actually decrease around equatorial regions, particularly among the tropical rainforests, because of increased rainfall.
The study, to be published Tuesday, June 12, in Ecosphere, an open-access, peer-reviewed journal of the Ecological Society of America, used 16 different climate change models to generate what the researchers said is one of the most comprehensive projections to date of how climate change might affect global fire patterns.
"In the long run, we found what most fear — increasing fire activity across large parts of the planet," said study lead author Max Moritz, fire specialist in UC Cooperative Extension. "But the speed and extent to which some of these changes may happen is surprising."
"These abrupt changes in fire patterns not only affect people's livelihoods," Moritz added, "but they add stress to native plants and animals that are already struggling to adapt to habitat loss."
The projections emphasize how important it is for experts in conservation and urban development to include fire in long-term planning and risk analysis, added Moritz, who is based at UC Berkeley’s College of Natural Resources.
UC Berkeley researchers worked with an atmospheric scientist from Texas Tech University to combine over a decade of satellite-based fire records with historical climate observations and model simulations of future change. The authors documented gradients between fire-prone and fire-free areas of Earth, and quantified the environmental factors responsible for these patterns. They then used these relationships to simulate how future climate change would drive future fire activity through the coming century as projected by a range of global climate models.
"Most of the previous wildfire projection studies focused on specific regions of the world, or relied upon only a handful of climate models," said study co-author Katharine Hayhoe, associate professor and director of the Climate Science Center at Texas Tech University. "Our study is unique in that we build a forecast for fire based upon consistent projections across 16 different climate models combined with satellite data, which gives a global perspective on recent fire patterns and their relationship to climate."
The fire models in this study are based on climate averages that include mean annual precipitation and mean temperature of the warmest month. These variables tend to control long-term biomass productivity and how flammable that fuel can get during the fire season, the researchers said.
Variables that reflect more ephemeral fluctuations in climate, such as annual rainfall shifts due to El Niño cycles, were not included because they vary over shorter periods of time, and future climate projections are only considered representative for averages over time periods of 20-30 years or longer, the authors said.
The study found that the greatest disagreements among models occur for the next few decades, with uncertainty across more than half the planet about whether fire activity will increase or decrease. However, some areas of the world, such as the western United States, show a high level of agreement in climate models both near-term and long-term, resulting in a stronger conclusion that those regions should brace themselves for more fire.
"When many different models paint the same picture, that gives us confidence that the results of our study reflect a robust fire frequency projection for that region," said Hayhoe. "What is clear is that the choices we are making as a society right now and in the next few decades will determine what Earth’s climate will look like over this century and beyond."
Study co-author David Ganz, who was director of forest carbon science at The Nature Conservancy at the time of the study, noted the significance of the findings for populations that rely upon fire-sensitive ecosystems.
"In Southeast Asia alone, there are millions of people that depend on forested ecosystems for their livelihoods," he said. "Knowing how climate and fire interact are important factors that one needs to consider when managing landscapes to maintain these ecosystem goods and services."
The researchers noted that the models they developed focused on fire frequencies, and that linking these to other models of fire intensity and vegetation change are important next steps.
"Our ability to model fire activity is improving," said Moritz, "but a more basic challenge is learning to coexist with fire itself."
The Natural Sciences and Engineering Research Council of Canada, the U.S. Forest Service, the National Science Foundation and The Nature Conservancy helped support this study.
RELATED INFORMATION
- Climate change to spur rapid shifts in fire hotspots, projects new analysis (2009 UC Berkeley press release)
- Author: Sarah Yang | Media Relations scyang@berkeley.edu, (510) 643-7741
The paper, published in the June issue of the peer-reviewed journal BioScience, and led by researchers at the University of California, Berkeley, synthesizes 20 years of research throughout the country on the ecological impact of reducing forest wildfire risk through controlled burns and tree thinning. It comes as California braces for a potentially bad fire season, particularly in the southern Sierra where precipitation was half its normal level.
"We need to act, because climate change is making fire season longer, temperatures are going up, and that means more fire in many regions, particularly ones with a Mediterranean environment," said study lead author Scott Stephens, UC Berkeley associate professor of fire science.
The study authors, which included scientists from the U.S. Forest Service and six research universities in the United States and Australia, relied upon data from the U.S. Fire and Fire Surrogates Study, in addition to a wide range of other studies. Together, the studies represented a broad spectrum of ecological markers, detailing the effects of fuel-reduction treatments on wildlife, vegetation, bark beetles, soil properties and carbon sequestration.
"Some question if these fuel-reduction treatments are causing substantial harm, and this paper says no," said Stephens. "The few effects we did see were usually transient. Based upon what we've found, forest managers can increase the scale and pace of necessary fuels treatments without worrying about unintended ecological consequences."
A few of the researchers’ specific ecological findings include:
- For the first five years after treatment, some birds and small mammals that prefer shady, dense habitat moved out of treated areas, while others that prefer more open environments thrived. The study authors said these changes were minor and acceptable.
- When mechanical tree thinning was followed by prescribed fire, there was an increase in the overall diversity of vegetation. However, this also included non-native plant species. The researchers recommend continued monitoring of this effect.
- Only 2 percent or less of the forest floor saw an increase in mineral soil exposure, which could lead to small-scale erosion. Other soil variables, such as the level of compaction, soil nitrogen and pH levels, were temporary, returning to pre-treatment levels after a year or two.
- Increases in bark beetles, a pest that preys on fire-damaged trees, was short-lived and concentrated in the smaller diameter trees. Researchers noted that thinning out a too-dense forest stand improves tree vigor and ultimately increases its resilience to pests, in addition to fire.
The results of this paper may help inform an analysis of one of the larger prescribed fires in the history of the U.S. Forest Service. Called the Boulder Burn, the proposed treatment covers 6,000-9,000 acres in the Southern Sierra Nevada's Sequoia National Forest and is tentatively set to begin by late fall.
"This paper is more comprehensive and definitive than any other article I've seen," said Malcolm North, research scientist with the U.S. Forest Service and an associate professor in forest ecology at UC Davis. "In one place, it summarizes the state of the science in fuel-reduction treatments, and to my mind, it shuts the door on those who say that any type of fuels treatment is detrimental to the forest. If done properly where surface fuels are reduced, treatments work. It's time to get on with it."
Nearly a century of fire suppression and the preferential logging of large-diameter trees, which are better able to withstand forest fires, have left forests vulnerable to more destructive, albeit less frequent, wildfires, the researchers said. In addition, the lack of fire has hindered nutrient cycling in forests and the proliferation of certain plant species, such as the sequoia, that rely upon fire to promote seed dispersal.
This realization led to the gradual re-emergence during the past 20 years of fuel-reduction as a forest management tool. The goal is simple: Thin or remove overly dense stands of trees, ground vegetation and downed woody debris in a carefully controlled way before they become fuel for a raging wildfire. When low- or moderate-intensity controlled burns are not an option, fire-prone trees are mechanically removed or shredded on site.
Such techniques are an attempt to emulate the frequent fires common in California for thousands of years. Before 1800, Stephens said, an estimated 1.1 million acres of forest burned annually in California, including wildfires ignited by lightning and other natural sources, and blazes set intentionally by Native Americans as a way to manage or alter landscapes. Most were blazes of low-to-moderate intensity that more than 80 percent of the trees could survive, unlike the catastrophic wildfires of modern times.
"Today, the combination of wildfires and fuel-reducing treatments only touch 6-8 percent of the land that used to burn annually before 1800, and fuel-reducing treatments alone only affect 1 percent," said Stephens. "That's a pittance. At that level, treatments are just triage rather than fire prevention."
To approach levels that have a chance of reducing wildfire risk in the long term, he said, the amount of land to be treated in a year would need to increase to 2-4 percent — still low compared to historical levels.
Stephens noted that two-thirds of the fuel-reduction treatments in the western United States rely upon mechanical thinning, which would be much more costly than prescribed burns to scale up. In the southeast region, the use of prescribed fire dominates.
In the West, particularly in California, the biggest challenge to expanding controlled burns is the potential reduction in air quality during treatment, said Stephens.
"We have a choice," he said, "of dealing with lower levels of smoke from prescribed fires that may only be needed every 15 years or so, and which can be timed for optimum wind conditions, or acute levels of smoke from catastrophic fires that can last for months when they hit."
The U.S. Department of Agriculture-U.S. Department of the Interior Joint Fire Science Program helped support this research.
- Author: Jeannette E. Warnert
Walter Bentley, UC Cooperative Extension advisor, transferred to Kearney in 1994 after 17 years as a UC Cooperative Extension advisor in Kern County, specializing in entomology. The integrated pest management team – with advisors representing the core pest management disciplines of entomology, nematology, weed science and plant pathology – was formed in response to concern about the effect of pesticides on food safety, the environment and farmworker safety.
Bentley collaborated with IPM and commodity-specific UC Cooperative Extension advisors and specialists and farmers to develop IPM approaches and alternative control strategies that have reduced the use of the highest risk insecticides (carbamates and organophosphates) in California by 80 percent to 90 percent in almonds, grapes and tree fruit since 1995.
Bentley’s career success is demonstrated by the numerous awards he has received in the past year. A group of world IPM leaders presented Bentley with its Lifetime Achievement Award March 27 at the 7th International IPM Symposium in Memphis, Tenn. He also received a Lifetime Achievement Award from the California Association of Applied IPM Ecologists in February. In October 2011, Bentley received the UC Agriculture and Natural Resources Distinguished Service Award for Outstanding Extension.
Bentley grew up in San Joaquin County on his family’s cherry, walnut and peach farm in Linden. He began laboring in the orchards as a young boy, but the hard work didn’t deter him from pursuing a career in agriculture.
“Growing up on a farm is probably the best life a youngster can have,” Bentley said. “But I can’t say that it was easy for my parents. It was a struggle for them to raise a family and depend solely on income from the farm.”
Bentley earned a bachelor’s degree in horticulture and biology in 1969 at Fresno State University, and then spent two years in the U.S. Army working on tracing mosquito movement in the 4th Army area of Texas and Oklahoma and later in Utah. He earned a master’s degree in entomology in 1974 at Colorado State University. Bentley worked in biological pest control for the Colorado Department of Agriculture before returning to his native California for the UC Cooperative Extension position in Bakersfield.
“I had heard many rumors about how tough Bakersfield was in terms of weather and environment. Within two weeks of starting the job, there was a huge dust and wind storm in the area and the first summer we had 30 days in a row with the temperature 100 degrees or higher,” Bentley said. “But I came to enjoy Bakersfield.”
As the UC Cooperative Extension farm advisor for Kern County, Bentley worked with his colleagues to develop an IPM program for almonds, addressing primarily problems with spider mites, navel orange worms and ants. Also working with colleagues, he developed an IPM program for potatoes, emphasizing careful monitoring for potato tuber moth and postponing pesticide treatment until the pest reached a level at which economic damage occurs.
Perhaps his greatest accomplishment, however, was the relationship he cultivated with growers and pest control advisers in Kern County. In particular, Bentley worked closely with pioneer Bakersfield apple grower Lewis Sherrill to combat the problem of codling moth in apples. Sherrill started his own farm at age 76 and continued farming until he was nearly 100 years old.
“Apple farmers in Kern County were relying on information from Washington state, where a large part of the U.S. apple industry is located,” Bentley said. “But in Washington, codling moth only produces two generations in the summer. In Kern County, we had four. Lou and I analyzed codling moth flight dynamics, integration of materials and we began experimenting with mating disruption.”
At Kearney, Bentley continued his work on apples and almonds, plus he began to work extensively in grapes. Mealybug management in grapes, he said, became the most important and impactful part of his job. Bentley also played a role in developing a management plan to control katydid damage in peaches and helped farmers use mating disruption against oriental fruit moth in peaches.
“In my generation as an entomologist, a major breakthrough was the development and use of pheromones for ag pest monitoring and management,” Bentley said. “We found ways to use pests’ own biology against them.”
During his 36-year career, Bentley authored 65 chapters or sections in pest management manuals and 75 peer-reviewed articles. In addition, he wrote more than 250 articles for trade journals and newspapers.
"Mr. Bentley's career represents the best UCCE's faculty has to offer, “ said his IPM colleague, Pete Goodell, UC Cooperative Extension advisor based at Kearney. “Unselfish service, loyalty to his peers and clientele, intellectual honesty, dedication to the mission of UCCE and a genuine love for his work.”
Bentley credits the success of his program to the UC Cooperative Extension research and education continuum, which is designed to foster communication and collaboration from campus laboratories to farm fields and back again.
“I think this is one of the best educational programs in the world,” Bentley said. “We take information from UC campuses to the farms. And those of us who work with farmers bring first-hand experiences back to the campus and work with scientists to develop solutions.”
Bentley’s personal interest in insects, which got him into his line of work, will carry through into his retirement. One of his goals, he said, is building a teaching collection of insects, spiders, mites and other arthropods at Kearney. He has already acquired some of the equipment needed to house the collection, and plans to maintain some samples on pinned displays and others in live colonies. The collection will be a learning tool for farmers, pest control advisers, students and interns.
“Knowing what’s out there is an important part of understanding entomological science,” Bentley said.
Insects are also a part of his favorite pastime, fly fishing. Bentley said retirement will give him more time to spend on local rivers catching (and releasing) trout with his hand-tied flies. Bentley speaks passionately about the joy of fly fishing.
“There’s a pulse that runs through you,” Bentley said. “It feels like you’re a child on Christmas every time the fish hits the fly. It’s such a thrill.”