Posts Tagged: pest
UCCE researchers target sugar-feeding ants, a key to controlling citrus pests, disease
Sugar-feeding ants protect pests that infect trees and damage the fruit they bear. Insecticides are often a go-to solution, but may kill beneficial insects in the process, too. Thankfully, Mark Hoddle, University of California Cooperative Extension entomologist and biological control specialist at UC Riverside, together with UCR colleagues in chemical engineering, developed a biodegradable hydrogel baiting system that targets ant populations, which protect sap-sucking pests from their natural enemies. Control of ants allows beneficial parasitoids and predators to greatly reduce pest populations.
Deciding to expand Hoddle's research was a “no-brainer” according to David Haviland, UC Cooperative Extension farm advisor in Kern County.
Haviland is investigating active ingredients that can be effectively used in hydrogel baiting systems. His research builds on Hoddle's use of alginate gels, also known as water beads, soaked in sugar water to control Argentine ants.
“What we're doing in California can benefit places like Florida, Texas, Mexico and beyond,” Haviland said.
The Hoddle lab conducted two years of orchard research showing that when ants are controlled, the amount of citrus flush infested with Asian citrus psyllid (ACP), a mottled brown insect that vectors the pathogen causing citrus greening, decreases by 75%. Citrus flush refers to newly developed leaves.
“But benefits are not restricted to just ACP with Argentine ant control, as natural enemies destroy colonies of other sap-sucking pests too,” said Hoddle. “For example, citrus mealybug infestations on leaves were completely eliminated by natural enemies, 100% control, while densities of fruit infested by mealybugs were reduced by 50%.”
The Hoddle lab's success inspired Haviland to consider how this approach will fare in different regions of the state where there are different crops, different pests and different ant species.
Haviland has worked for many years on solid baits that are effective and affordable for ants that feed primarily on protein, like fire ants in almonds, but successful control measures for sugar-feeding ants that drink their food have been elusive.
“Therefore, we're using hydrogels to essentially turn a liquid bait into a solid, making it effective and commercially adoptable,” Haviland said. He and his team are assessing whether active ingredients that undoubtedly work against ants, like thiamethoxam, maintain their effects in a hydrogel system.
Unlike Hoddle's biodegradable alginate gels, Haviland is relying on acrylamide gels that are similar to the absorbing material you would find in a diaper. These gels are not organic, but are currently accessible on a commercial scale, and have been shown to be effective in wine grapes on the North Coast by a Cooperative Extension advisor in Napa County, Monica Cooper. Haviland's current research efforts are focused on citrus, table grapes and wine grapes in the San Joaquin Valley, and on lemons on the coast.
The primary challenge now is navigating pesticide regulations and registration.
“This is cutting-edge research,” Haviland said, and manufacturer labels for the products being used need to be updated to include hydrogels as an approved use. This process takes time. Additionally, adding new product uses needs to make economic sense for the manufacturer.
Hoddle and Haviland's research can provide data for adding these methods to the product labels.
“If we can show that this tech works against lots of pests, lots of ant species, in lots of different crops across California, hopefully we'll achieve a critical mass of benefits that motivates product manufacturers to make modifications to their labels,” said Haviland.
Haviland is hopeful about the process, and said he believes that UC ANR is in a prime position to lead innovation for an issue that requires collaboration among specialists, advisors and the industry.
New online pesticide-use course aims to protect water quality
Do you know that some pesticides used around homes and other structures are toxic to small aquatic organisms living in nearby streams, creeks, rivers and oceans? The UC Statewide Integrated Pest Management Program has launched a new online course on runoff and surface water protection in California. This course is designed for pest management professionals working primarily in structural pest control or landscape maintenance, but residents and property managers may also find the presented information useful.
Developed by pest management experts from the California Department of Pesticide Regulation (DPR) and the University of California, this course presents information on the Surface Water Protection Regulations that are found in Title 3 of the California Code of Regulations. These regulations were put into place to prevent pesticide runoff into California waterways and to reduce surface water contamination from pyrethroid insecticide use.
In this course, you will learn about the types of pesticide applications that are allowed under the regulations, as well as application types that are prohibited and also application types that are exempt. The course takes a close look at pyrethroids, particularly bifenthrin because of its high use in urban areas, high detection in surface waters, and high toxicity to aquatic organisms. Fipronil, another commonly used ingredient in structural and landscape products, is addressed in the course as well because it causes similar water-quality concerns as pyrethroids. Bifenthrin is used for managing pests such as ants, crickets and lawn grubs. Fipronil is used for ants, roaches and termites.
The Urban Pyrethroid and Fipronil Use: Runoff and Surface Water Protection course has been approved by DPR for a total of 1.5 continuing education units, including 0.5 hour of Pesticide Laws and Regulations and 1.0 hour of Other and by the Structural Pest Control Board for 1.5 hours of Rules and Regulations.
The course takes about 90 minutes to complete. It is divided up into seven sections so a person can stop and resume where they left off. The course is free. To take the course, people need to set up an account at https://campus.extension.org/ then they can enroll. The direct link to the course is https://campus.extension.org/course/view.php?id=2221.
UC IPM currently offers 22 online courses with continuing education units from DPR. Many of these courses are also credited by the California Structural Pest Control Board, Certified Crop Adviser, the Western Chapter of the International Society of Arboriculture, and the Arizona Department of Agriculture.
After shothole borer invasion, UC Irvine becomes ‘perfect testing ground’
Results help inform best practices for managing the disease-causing beetle
The University of California, Irvine campus is home to a vast urban forest consisting of approximately 30,000 trees located in a mix of landscape, riparian and open space settings. In the mid-2010s, that forest came under threat from an invasive species of beetle that arborists and pest researchers were just learning about – the polyphagous shothole borer.
The tiny beetles, which may have arrived in California from their native Southeast Asia via infested shipping materials, tunnel into trees and introduce a fungus that serves as food for adult beetles and their larva.
As the fungus grows, it colonizes the tree's vascular system, blocking transport of water and nutrients. This causes a disease called Fusarium dieback that can kill branches or entire trees.
One reason the beetles were such a threat at UCI was the high number of sycamores on campus, especially in Aldrich Park at the campus center. Hundreds of cottonwoods, native willows, golden rain and coral trees also were affected. In total, the beetles attacked more than 2,000 trees, including 75 different tree species.
A variety of approaches to controlling beetle
To better understand and tackle this problem, UCI's Facilities Management department and Office of Environmental Planning and Sustainability collaborated with researchers affiliated with UC Agriculture and Natural Resources and UC Cooperative Extension. In addition, pesticide-manufacturing companies, pest control advisers and arborists provided materials and labor to help offset the cost of research.
“UCI was the perfect testing ground to determine integrated pest management strategies for this beetle/disease complex,” said John Kabashima, UCCE environmental horticulture advisor emeritus. “Our research was multifaceted, delving into early detection, monitoring and sampling, and cultural and chemical management.”
Kabashima said UCI provided the researchers with “a lot of freedom” to try a variety of approaches and study the results over time.
“We could cut down and sample trees or leave selected infested trees alone; we explored a variety of pesticide/fungicide combinations and application techniques,” he said. “That freedom resulted in many of the management solutions that are used today to effectively control this pest.”
UCI and the researchers also established a full inventory of affected trees on campus, evaluating severity of infestation by the number of entry/exit holes and signs of dieback. One important key to management is getting rid of “amplifiers” – heavily infested trees that are both hazardous and a source of beetles to spread to other trees.
“Typically, shothole borer infestations begin with just a few trees that for some reason are highly attractive to the beetles – perhaps based on tree species, tree spacing, irrigation conditions or other factors,” Kabashima said. “Over time, the beetles and fungus multiply largely undetected in those few trees. When the beetle population reaches a critical point and the trees begin to die, the female beetles fly to adjacent trees in a secondary invasion, eventually infesting many trees over a large area.”
An opportunity to diversify UCI's urban forest
At UCI, that initial invasion took place in landscaped areas containing many large, majestic sycamores that were planted when the campus began operations in the mid-1960s.
Over several years, UCI removed 700 heavily infested trees, including many of those historic sycamores, and replaced them with other tree species.
Today, the forest at UCI is very different than it was in 2015. While shothole borers have not been eliminated completely, their presence is reduced significantly, and UCI now has the tools to manage them effectively. Reforestation efforts resulted in a diverse treescape that is not only more sustainable but also beautiful.
“Managing a 1,500-acre campus with 30,000 trees is a never-ending process,” said Richard Demerjian, UCI's assistant vice chancellor, Campus Physical & Environmental Planning. “Our forest continues to evolve, with an ongoing focus on increasing diversity and plant health.”
Demerjian also noted that UCI is now starting to consider planting new sycamore trees on a limited basis.
A primer on effective shothole borer management
Whether managing a forest of thousands of trees or just a few trees, landscape managers and residents can apply many of the lessons learned at UCI to control invasive shothole borers and other tree pests.
- Avoid monocultures. Tree diversity provides beauty and resiliency.
- Keep trees healthy. Proper irrigation and maintenance will keep trees strong and help protect them from shothole borers and other pests.
- Check trees. Look for the common signs and symptoms of infestation such as beetle entry/exit holes. Regular monitoring ensures that infestations are managed early, before they cause dieback or tree death.
- Confirm suspected infestations. Use the detection tool at www.ishb.org.
- Review management options. For trees with low infestation, prune the infested branches and monitor the tree's health over time. In non-riparian, urban settings, consider treating low and moderately infested trees with pesticides/fungicides demonstrated to be effective against the pest-disease complex (A licensed professional will be needed to apply the treatments). Severely infested trees may require removal.
- Call in a professional. A certified arborist or pest control professional would be able to provide recommendations based on the tree's condition. The local county Agricultural Commissioner's Office and UC Cooperative Extension office may have additional knowledge about current shothole borer monitoring and management programs in your area.
- Take care of green waste. The beetles can survive in cut wood for weeks or even months. Proper disposal of green waste includes chipping infested wood, followed by solarizing or composting the chips.
- Replant wisely. Begin planting new trees only after removing all amplifiers and establishing an ongoing monitoring program. Consider the current concentration of tree species when deciding what type of trees to plant.
More detail, key updates in new edition of pesticide safety manual
Publication in English, Spanish prepares private applicators for state exam
Expanded from four chapters in the previous edition to 12, the third edition of Pesticide Safety: A Study Manual for Private Applicators aims to be more than just a study guide.
The manual, available for purchase in English and Spanish, provides much more detail on essential processes and procedures that will help keep applicators safe while using pesticides – as well as reduce environmental impacts from misapplication.
Published by University of California Agriculture and Natural Resources in collaboration with the state's Department of Pesticide Regulation, the manual – intended for members of the agricultural community who own, manage or work on farms that use restricted-use pesticides – also includes substantial updates.
“The information in the book they were using was way out of date,” said writer/editor Shannah Whithaus, senior editor for pesticide safety education with UC ANR's Statewide Integrated Pest Management Program. “Also, the book was much, much shorter than it needed to be, because it wasn't providing enough information for people to safely apply pesticides, given the complexity of the regulatory environment we're in now.”
The new manual reflects important changes to federal and state regulations since the publication of the previous edition in 2006.
“There are significant regulatory updates which help you stay up-to-date with safety rules and standards – and protect your workers from overexposure to pesticides,” said Lisa Blecker, technical editor of the publication, and currently a pesticide safety educator at Colorado State University.
In addition to emphasizing the broader ecological ramifications of improper pesticide use, the manual includes information on subjects that might get short shrift in other manuals, such as the correct calibration of equipment to ensure accuracy of application.
“All of that is now in the book and fully fleshed out,” Whithaus said. “[Applicators] are going to be able to do that much more effectively using the new book, compared to the old one – it was really hard to be thorough in 80-some pages.”
The new edition – totaling more than 200 substantive pages – also features a more streamlined and user-friendly layout modeled after a sister publication, The Safe and Effective Use of Pesticides, written for commercial applicators.
“A significant update is a layout that is not only beautiful, but helps you identify key information you need to know in order to make safe and effective pesticide applications,” Blecker explained.
She highlighted the “knowledge expectations” listed at the beginning of each chapter and in the margins of the book, next to the relevant passages. The statements serve as “visual cues” to help readers learn and retain the material they need to pass California DPR's certification exam for private applicators.
And while the manual functions as an improved study aid for owners, managers and workers who apply pesticides, it doubles as a reference that they can turn to for years to come.
“It's going to be able to serve as a reference manual, as opposed to just a study guide,” Whithaus said. “You really will be able to use this book as a tool to help you do better in managing your land.”
The manual, listed at $29, is available for purchase in English at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3383 and in Spanish at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3394./h4>
UC explores alternatives to fumigants for strawberries
Strawberries, which generated $2.2 billion for California growers mainly on the coast in 2019, are sensitive to soilborne diseases. Strawberry plant roots infected by fungi are unable to take in nutrients and water, causing the leaves and stems to wilt. The diseases reduce fruit yields and eventually kill infected plants.
To protect the delicate plants from pathogens, strawberry growers fumigate the soil with pesticides such as chloropicrin and 1,3-dichloropropene before planting transplants. Due to the potential negative effects on the environment and human health, however, use of fumigants are highly regulated and developing non-fumigant alternatives has been a priority of the strawberry industry.
For a biological alternative to manage soilborne diseases in strawberries, Joji Muramoto, UC Cooperative Extension organic production specialist based at UC Santa Cruz, has received a $411,395 grant from USDA National Institute of Food and Agriculture to study the ability of other crops to suppress strawberry pathogens in the soil.
Verticillium wilt, caused by Verticillium dahliae, is a common soilborne disease that can be controlled with anaerobic soil disinfestation (ASD), a fermentation-based biological treatment using carbon sources such as rice bran under plastic mulch in moist soils for 3 to 5 weeks in autumn. About 2,000 acres of berry fields, mostly organic, were treated with ASD in California and Baja California, Mexico, in 2019.
In 2008-09, the diseases fusarium wilt, caused by Fusarium oxysporum f. sp. fragariae, and charcoal rot, caused by Macrophomina phaseolina, emerged in Southern California and now threaten strawberry plants throughout the state.
ASD isn't as effective against F. oxysporum and M. phaseolina unless it is applied in summer on the coast. As saprophytes, they feed not only on living plants, but also can colonize crop residues and rice bran especially at lower coastal temperatures in autumn. Treating fields on California's coast with ASD during summer is difficult because it competes with the vegetable production period.
Based on promising studies in Asia and other areas, Muramoto plans to test alliums – such as onion, bunch onion and leek – and a certain variety of wheat (Summit 515) to see if they will suppress F. oxysporum and M. phaseolina. His team will conduct a series of greenhouse and field trials and test these crops with and without ASD to compare the effects on soilborne pathogens.
“Studies have shown the potential of using allium crops to control Fusarium wilt, and Summit 515 wheat for charcoal rot,” Muramoto said. “Our goal is to examine the effectiveness of suppressive crops, optimize them for California strawberry production systems, and evaluate their economic feasibility for commercial use.”
“No single tactic is likely to replace fumigants,” he said. “Integration of multiple biological approaches such as crop rotation, ASD, and use of resistant strawberry varieties is a key to develop a successful non-fumigant-based soilborne disease management strategy for strawberries. This project is a part of such broader efforts.”
At the end of the three-year study, he plans to share the results at workshops, field days and webinars.
Rachael Goodhue, UC Davis professor of agricultural economics; Carol Shennan, UC Santa Cruz professor of environmental studies; and Peter Henry, USDA Agricultural Research Service plant pathologist, are co-principal investigators on the study with Muramoto.
Also collaborating on the project are Christopher Greer, UC Cooperative Extension integrated pest management area advisor in San Luis Obispo County; Oleg Daugovish, UCCE vegetable and strawberry advisor in Ventura County; Mark Bolda, UCCE director strawberry and cane berry advisor in Santa Cruz County; Jan Perez, food systems specialist, and Darryl Wong, farm research manager, at UC Santa Cruz Center for Agroecology and Sustainable Food Systems; Miguel Ramos of Ramos Farm; Agriculture and Land-Based Association (ALBA); Driscoll's; Naturipe; and The Oppenheimer Group.