At an invasive species summit last year in Sacramento, UC ANR vice president Glenda Humiston and California Department of Food and Agriculture secretary Karen Ross convened scientists, government representatives and volunteers to pool intellectual resources and plot a strategy for protecting agricultural crops, natural resources, cityscapes and residential neighborhoods from invasive species.
“We know that collectively, we have the tools and expertise to prevent invasive species from entering California, spreading and becoming established,” Humiston said.
Below are three examples of pests that entered California, and with research, collaboration and treatment, were eradicated from the state.
European grapevine moth
European grapevine moth, a native of Mediterranean Europe, was detected for the first time in the Americas in Chile in April 2008. The following year, European grapevine moth was found in California's iconic wine region, Napa Valley. From there it spread to nine other California counties, as far south as Fresno. UC ANR academics responded rapidly — working with public and private partners and international scientists — to develop a pest management program that relied on deploying pheromone dispensers to disrupt mating and application of carefully timed insecticides. UC ANR academics studied the moth's biology, life cycle, host range and proven management practices. In short order, the moth population plummeted, and eventually the state was declared free of European grapevine moth, lifting a quarantine, enhancing farmers' ability to export their agricultural products, and preserving the communities' economic wellbeing. More info: Growers, scientists and regulators collaborate on European grapevine moth program
Pink bollworm of cottonIt took 50 years, but the invasive pink bollworm of cotton was declared eradicated in California in 2018. Eradication of pink bollworm was a joint effort by UC Cooperative Extension, USDA's Agricultural Research Service, county agricultural commissioners' offices and California cotton growers. It involved the implementation of integrated pest management techniques, such as planting transgenic cotton, using insect pheromones to disrupt mating, releasing sterile insects to slow reproduction, plowing after each crop to provide host-free periods, and extensive surveying. California cotton growers funded the program by paying an assessment on cotton grown in the state. More info: Pink bollworm UC Pest Management Guidelines
Red palm weevilIn August 2010, arborists removed a dying Canary Island date palm from the yard of a Laguna Beach home and reported finding large black and red striped beetles. The pests were confirmed to be the first record of the destructive red palm weevil in the U.S. Hormone monitoring and visual surveys of other palms in the area confirmed the presence of the pest. Rapid action was taken against the pest by applying pesticides to trees that showed feeding damage to palm fronds. Effective surveying was accomplished by combining hormone attractants and cut pieces of palm trees provided by the California date palm industry. The last live weevil was detected in Laguna in January 2012. After three years passed with no weevil detections in Laguna Beach, USDA-APHIS declared this pest to be officially eradicated in January 2015. More info: Red palm weevil successfully eradicated form California
Asian citrus psyllid was first identified in California in 2008, and has been found from San Diego and Imperial counties in the south, all the way to Sacramento County in the north. See a map of Asian citrus psyllid and huanglongbing distribution in California.
UC Agriculture and Natural Resources specialists and advisors are working with the citrus industry, USDA and CDFA to control ACP populations and keep HLB contained while researchers search for a cure for the disease.
In order to find and remove infected trees before ACP can spread the disease to other trees, UC scientists are focusing research on early HLB detection technologies (EDTs). When infections first start, the bacteria are in just a few leaves. If the sampler doesn't collect those leaves, the disease can be missed. It can take one to two years for the bacteria to distribute itself throughout the tree so this sampling error doesn't occur.
Early detection technologies use whole tree responses to early infections. For example, Carolyn Slupsky, food science and technology professor at UC Davis, measures changes in tree metabolism (its day-to-day chemical function) when it becomes infected. Every leaf on the tree is connected to the tree's metabolism, so it doesn't matter which leaf is collected. This type of test can detect an infected tree within weeks or months after infection instead of years.
Scientists are also studying ways to modify ACP so the insects are unable to spread HLB, and studying the use of conventional breeding, genome editing or genetic engineering to develop disease-resistant citrus. Read summaries of the research here.
View a four-minute video that shows how to monitor for ACP presence in residential citrus:
Scientific evidence of a warming climate in California and across the globe is clear, but the impacts on ecosystems and agriculture are still difficult to predict.
Sophisticated computer models are used to forecast future climate. Understanding that temperature and precipitation levels will change in the future does not tell the full story: UC Agriculture and Natural Resources researchers also want real-world experience under those future conditions.
Moreover, some agricultural operations have higher sensitivity to the changes than others. Rangeland forage is particularly sensitive to climate changes since, unlike irrigated agriculture, ranchers rely solely on precipitation. They have no control over how much and when it rains.
“It's tricky business,” said rangeland expert Jeremy James, the director of the UC Sierra Foothill Research and Extension Center in Browns Valley. “It's not easy to forecast. We have to address the uncertainty in a realistic manner.”
Discovering climate change impact on rangeland
In order to study different climate projections on rangeland, James and Maggi Kelly, director of the UC ANR Informatics and Global Information Systems special program, have begun development of a research site that will allow scientists to manipulate the temperature and rainfall on sections of rangeland to understand what would happen under predicted weather scenarios.
“We need to know how rangelands will respond when conditions change,” James said. “Will we grow more, but dry out earlier? Will we have more medusahead (an undesirable rangeland weed) or more soft chess (a high quality forage)?”
When complete, 16 shelters on steel tracks will be connected to computer systems and hydraulic motors to move them up or down a research plot. The shelters and other equipment will allow scientists to precisely control the amount of precipitation (or irrigation water) that rains onto the plot. Other systems will give researchers control of air temperature.
“This facility isn't designed for one type of research,” James said. “It is designed to conduct a wide variety of research by scientists over the next several decades. With this setup, we can look at the effect of climate change on soil biological communities, soil carbon, insect communities, plant-insect interactions and oak seedling recruitment.”
The research results from the project should provide ranchers and land managers a better understanding of how climate change may impact agriculture and ecosystem function on rangeland while also providing important information on how to minimize impacts of these changes.
Some aspects of the research facility's development are not covered with funding from the National Science Foundation. The scientists are looking for additional support to complete the project.
For more information, contact James at firstname.lastname@example.org.
Current work underway at the Sierra Foothill Research and Extension Center
The Sierra Foothill REC, a 5,000-acre facility on the Yuba River, has supported research, education and outreach in the Sierra foothills since 1960. Multiple lines of research are being conducted at SFREC. During a recent workshop, scientists from UC Davis, UC Berkeley and UC Cooperative Extension shared a sampling of their work at SFREC.
UCCE livestock and natural resources advisor Dan Macon described a project aimed at helping ranchers make decisions about maintaining a cattle herd when faced with impending drought. Ranchers are reluctant to sell off their cattle even when the near future weather forecast is dire.
“Science tells us you shouldn't feed your way out of a drought,” Macon said. “But you want everything to stay the same. You want to maintain your genetic potential and keep cows that are familiar with the area.”
Working with ranchers, the research project will compare management practices to determine the best way forward when the future looks meteorologically bleak.
“We're assigning cows to a traditional weaning and early weaning groups,” Macon said. “They'll be out on the range from March to early September under different parameters. We're also tying in economics, the value of genetic potential and the value of having cows who know the landscape.”
Research by University of Oregon post doctorate researcher Ashley Shaw is looking into whether compost applied to rangeland will help mitigate climate change by sequestering more carbon, and also benefit forage under drought by increasing the soil's water-holding capacity and improving nutrient delivery.
Preliminary results are promising. A single application of 1/4-inch of compost resulted in forage production that was higher than areas where no amendment was applied and areas that were treated with a chemical fertilizer.
“The biggest impact was under drought shelters,” said Shaw, referring to PVC frames that were covered with plastic during rain events to understand the impact of the treatment under dry conditions. “In the drought plots, the areas where compost was applied are staying green longer.”
A defining research tool at SFREC is a dataset that includes information on monthly rainfall and forage production going back 40 years.
A review of the data shows surprising variations and correlations at the center, where forage production averages 3,000 pounds per acre, but ranges from about 1,000 pounds per acre in 1987, to over 5,000 pounds per acre in 2018, when there was so much growth, “we didn't have enough animals to graze,” James said.
The dataset paints a spectrum of the variation that ranchers across the state must navigate to manage their livestock and rangeland in a way that is profitable and ecologically sound. Research at the Sierra Foothill REC offers invaluable information to help them better understand the ecosystem and make informed decisions.
When insects, animals, weeds and disease-causing microbes make their way into California from other parts of the nation or the world, the economic and environmental impacts can be catastrophic.
A recent UN report that details the world's biodiversity crisis assigns part of the blame to the proliferation of invasive alien species. “The numbers,” the report says, “have risen by about 70%, across the 21 countries with detailed records” since the 1970s.
“It's time to better understand how invasive species affect California's biodiversity, as well as our water supply, fire regimes, recreation and agriculture,” said Sabrina Drill, UC Cooperative Extension natural resources advisor in Los Angeles and Ventura counties. Drill worked with the California Invasive Plant Council and the California Department of Fish and Wildlife to offer five free 40-minute mid-day webinars on invasive species as part of the multi-agency sponsored California Invasive Species Action Week.
During the first part of the week the series cover a range of organisms, from killer algae and incestuous beetles to rodents of unusual size. Later in the week, it's Weeds-A-Palooza, with talks focusing on invasive plants.
The webinars will be offered using Zoom Video Communications from 12:10 to 12:50 p.m June 3-7. All details are available online at https://ucanr.edu/sites/invasivelunch/invasivelunch2019/. Links to the Zoom meeting space will be posted on that webpage before the webinars begin.
Sabrina Drill, UCCE natural resources advisor, and Edwin Grosholz, Department of Environmental Science and Policy, UC Davis
Most people only hear about an invasive species when they are here causing problems. But preventing new invasive species from getting here in the first place requires understanding the “pathways” of introduction. From tsunamis to aquariums, container ships to canoes, Grosholz and Drill will discuss ways that freshwater and marine organisms travel to California, and how we can prevent spreading them once they arrive.
Tuesday, June 4: “What's killing California's trees? Shot hole borers, palm weevils and the rest”
Beatriz Nobua-Behrmann, urban forestry and natural resources advisor, UC Cooperative Extension in Orange County
Tree pests come to Golden State from around the world and threaten street trees, agriculture, and natural areas. Last year the legislature in Sacramento allocated $5 million to begin addressing the latest threat – shot hole borers that kill a wide variety of trees in Southern California. Nobua-Behrmann will describe how these insects damage trees and what we can do about it.
Valerie Cook-Fletcher, Nutria Eradication Incident Commander, California Department of Fish and Wildlife
Nutria, a South American rodent, have caused extensive damage in Louisiana wetlands for decades. Now nutria have been found in the Sacramento-San Joaquin River Delta and its tributaries and state agencies are working to find them before they can breed and spread. Cook-Fletcher will provide an update on efforts to locate this elusive swimmer in the maze of sloughs and backwaters of California's San Joaquin Valley.
Thursday, June 6: “Citizen stewardship: Tackling giant reed in Contra Costa County”
Mike Anciaux and Bob Simmons, Walnut Creek Watershed Council
Giant reed (Arundo donax) is one of the most damaging wildland weeds in California. More than $20 million was spent to remove it from the Santa Ana River watershed in Southern California to protect the endangered Least Bell's Vireo, a songbird that nests in native streamside vegetation. On the eastern side of San Francisco Bay, citizens are uniting to find and remove hundreds of populations along Contra Costa County's creeks.
Eric Wrubel, San Francisco Bay Area Network, National Park Service
Invasive knotweed species are some of the worst weeds in the world. They have become notorious for destroying property values in Europe. Knotweed is extremely difficult to get rid of because its underground rhizomes store energy and resist herbicides. Wrubel will describe the partnership that has formed to eradicate recently found invasive knotweed in the San Geronimo Valley and Lagunitas Creek watersheds in Marin County before it can spread.
When Alejandro Del Pozo-Valdivia started his new job as UC Cooperative Extension entomology advisor in the Salinas Valley last year, he immediately faced an urgent problem in organic lettuce production.
Pest control advisers were finding lettuce aphids in plants that were supposed to be resistant.
Because lettuce aphids crawl deep within the heart of the lettuce head, and because organic growers do not have many options for chemical pest control, the industry relies on patented lettuce varieties that have been conventionally bred to be unpalatable to the pest.
“With other types of aphids, they stay on the outer leaves. When you harvest and clean the head, you are taking the aphids out,” Del Pozo-Valdivia said. “But with the lettuce aphid, it's almost impossible to remove them. We don't want consumers to buy a lettuce with these tiny red insects inside.”
Organic producers pay a premium for resistant seeds to grow lettuce without the lettuce aphid and are mystified by the sudden appearance of the pest inside lettuce heads. Has the aphid developed the capability to feed on resistant varieties? Is there a different lettuce aphid biotype in the area? Since Del Pozo-Valdivia is an entomologist, he is focusing on the pest.
With funding from the California Leafy Green Research Board, Del Pozo-Valdivia and his co-principal investigator, USDA scientist Jim McCreight, have launched a research project to collect and identify the lettuce aphids that are feeding and reproducing in the resistant lettuce in the Salinas Valley.
“I'm asking growers and PCAs to contact me if they find any red aphids in resistant lettuce so we can confirm the type of aphid,” Del Pozo-Valdivia said. “
Seed companies that hold the patent on resistant lettuce also experienced broken resistance in Europe a few years ago, Del Pozo-Valdivia said. They found that the pest in Europe was a different biotype and are already working on identifying genes to maintain the lettuce aphid resistance.
“We haven't seen any scientific report for the U.S. That's why we decided to take the lead. To take the bull by the horns and identify the aphids here in the Salinas Valley,” Del Pozo-Valdivia said.