Posts Tagged: willow

Shot Hole Borer Training

field id

Invasive Shot Hole Borer Gone Global

Natural Resources Advisor, UC Cooperatiove Extension

With a finding in the KwaZulu National Botanical Gardens reported in November 2017, the invasive shot hole borer (ISHB) (polyphagous and Kuroshio borers)/ fusarium dieback pest disease complex is now known to be found on three continents. Native to parts of Asia – polyphagous SHB comes from Vietnam, while Kuroshio SHB is native to Taiwan – the problems has spread to Israel, the US, Mexico, and now South Africa. Since first being discovered, PSHB has been identified in urban areas in parts of the country that are several hundred miles apart – from Durban on the east coast to the large metropolitan area of Johannesburg further north, with the Botanical Garden in-between. Samples from the city of George, in a region on the southern coast known as the Garden Route, are currently being analyzed. South Africans are very concerned about the potential to damage their extensive urban forests and are developing a national surveillance and management plan. KwaZulu National Botanical Garden is part of the International Plant Sentinel Network, where exotic species are grown to provide an early warning system for emerging pests. The US counterpart if the Sentinel Plant Network run by the American Public Gardens Association and the National Plant Diagnostic Network. Finding this pest serves as a case in point on the value of these kinds of international networks in the battle against invasive pests.

Closer to home, there is actually, potentially, maybe some good news from the Tijuana River Valley. This is the valley that has been the hardest hit by the KSHB. In 2015 the natural willow forests were tall and lush and then just a few months later they were devastated - the before-and-after photos of this event have become iconic. John Boland, a researcher working in the Tijuana River Valley reports that in areas that were severely damaged by the pest, the willows are now vigorously recovering. They are growing back from their stumps via long re-sprouts, and this new growth is not showing signs of attack. Surveys in 2017/18 found a 6% median infestation rate, down from a 97% infestation rate observed in 2015/16. The initially observed high infestation rates in the wet forest areas may have been influenced by extremely high sewage pollution into the Tijuana River, and these high infestation rates are unlikely to occur elsewhere. Boland's “soft tree hypothesis” states that willows growing in nutrient enriched waters grow quickly, laying down wood with low density and high water content, i.e., they have ‘soft' wood. This kind of growth promotes beetle infestation, as it's easy to create tunnels, and favorable for the fungal symbiont. Willows growing elsewhere would have ‘hard' wood and suffer fewer beetle attacks. His initial data analysis supports this hypothesis. If true, this would mean that riparian areas with higher quality water could see much less severe infestation. It will be interesting to observe variations in infestation ecology around the region. Damage to avocado groves in California appears to be less severe than initially anticipated – I hope the same is true for natural areas.

Boland, J.M. 2018. The Kuroshio Shot Hole Borer in the Tijuana River Valleyin 2017-18 (Year Three):
Infestation Rates, Forest Recovery, and a New Model. Final Report for US Navy, US Fish and Wildlife Service and Southwest Wetlands Interpretive Association. 74 pages.

Photo: A typical resprouting arroyo willow. The original trunk is large, broken and riddled with KSHB holes. At the time of the photo, the four vertical resprouts were growing strongly and had no KSHB holes. (John Boland)

Boland willow

Shot Hole Borer Studies are Going on Throughout Southern California

Many growers don't hear about the amount of research and extension activity that is going on surrounding the Shot Hole Borers and Fusarium Dieback.  This pest/disease complex affects not only avocados, but many other tree species, including many California natives. These are the notes from a Collaborative organized by UC ANR.  There is a lot of energy by a lot of groups addressing this massive problem.

Invasive Shot Hole Borer (Polyphagous and Kuroshio)/Fusarium Dieback

Quarterly Situation Report

January 1 through March 31, 2017

Executive Summary

Overview

No spread of invasive shot hole borer/Fusarium dieback (ISHB/FD) was reported this quarter, which may have been due to cool seasonal temperatures and resulting insect inactivity. The period served to establish new trapping sites, evaluate programs, and establish new ones.

Trapping locations expanded in Orange, Ventura, and Santa Barbara Counties. A new trapping program was started that serves the Santa Monica Mountains, Conejo and San Fernando Valleys.

An urban observational project modeled after successes in Orange County was initiated in Ventura County. The project can potentially expand monitoring by citizen scientists throughout the region to benefit tracking and treatment.

Representatives of various public, academic, and private entities from seven of the nine southern California counties participated in activities, which are summarized below

Statewide

o   ISHB/FD dialogue continued between counties, Agricultural Commissioners, and other stakeholders through conferencing hosted by the California Agricultural Commissioners and Sealers Association.   Education and outreach to counties without infestations is tantamount for detection and readiness

o   Outreach was initiated to Inyo and Mono Counties in eastern California

o   Legislative outreach and education continued to State Assembly and California Department of Food and Agriculture

o   California Department of Fish and Wildlife hired staff for ISHB monitoring, trapping, developing a wildlands field guide, and creating a management matrix

o   Media interviews about ISHB/FD were conducted for publications, many of which are circulated online.

Regional

o   Two ISHB/FD working groups met:

1. Emerging Tree Pests Education& Outreach Subcommittee (5x)
2. Natural Resources/Urban Forest SHB Coalition (3x)

o   University of California (UC) researchers continued investigations with bio-control agents and pesticides to combat ISHB/FD

o   A UC publication focused on ISHB/FD invasion to palm trees was published

San Diego County

o   The Resource Conservation District of San Diego researched funding to continue ISHB/FD monitoring, trapping, education, and outreach needs

o   Southwest Wetlands Interpretive Association continued studying the SHB infestation and found that an estimated 88% of plant material in the Tijuana River Valley was affected despite recovery following massive SHB-caused dieback in 2016

o   UC-ANR & the Emerging Tree Pests Education and Outreach Subcommittee organized and presented the Southern California Green Waste and Wood Biomass Symposium held in San Diego

Riverside County

o   California Association of Certified Pest Control Advisors and University of California Agriculture and Natural Resources Division (UC-ANR) presented a half-day ISHB/FD workshop in Temecula

o   ISHB/FD training for State Parks rangers from the Inland Empire District was held in La Quinta

Orange County

o   California Department of Fish & Wildlife added new trapping and monitoring sites that included nature preserves, large institutional campuses, and parkways

o   California State Parks trapped at Crystal Cove, with no positive finds

o   ISHB/FD training was conducted for US Fish & Wildlife Service staff

o   Monitoring protocols for oak and sycamore were developed for the 4000-acre Audubon Starr Ranch in Trabuco Canyon

o   Orange County Master Gardeners received ISHB/FD training

o   Orange County Parks expanded trapping and monitoring activities to more parks, with Irvine Regional Park a focal point

o   Outreach continued throughout the county, with added focus to the business community

Los Angeles County

o   The Huntington continued monitoring its 207-acre parcel

o   The Resource Conservation District of the Santa Monica Mountains (RCDSMM) initiated trapping in the Santa Monica Mountains with partner National Park Service (NPS) – Santa Monica Mountains National Recreation Area

o   RCDSMM conducted trap making and trapping workshops for trapping in the San Fernando Valley and Santa Monica Mountains

o   UC-ANR met with City of Downey staff to discuss current infestations and monitorin

Ventura County

o   California Association of Certified Pest Control Advisors and University of California Agriculture and Natural Resources Division (UC-ANR) presented a half-day ISHB/FD workshop in Ventura

o   Master Gardener urban observation project began

o   RCDSMM and NPS established trapping sites in the Santa Monica Mountains/Conejo Valley area

o   UC Santa Barbara and UC-ANR coordinated an all-day meeting of the Santa Clara River Academic Coalition to discuss research being conducted in the watershed

o   Ventura County Agricultural Commissioner continued monitoring traps at avocado orchards in the Santa Paula area

o   UCSB continued trapping in riparian areas in the Santa Clara River watershed and started establishing sites in the Ventura River corridor

Santa Barbara County

o   Santa Barbara County SHB Working Group met (1x)

o   UC-ANR education and outreach was delivered by print and online media, tabling, and public events

o   UC-ANR met with Montecito Fire Department and the Santa Barbara County Fire Safe Council to discuss ISHB/FD threat

o   UCSB/UCR continued monitoring traps in the Montecito area and established new sites in the City of Santa Barbara foothills

San Luis Obispo County

o   CAL FIRE explored funding for trapping, monitoring, education and outreach

  

PSHB Working Group Coordination

Active groups – regionwide

o   There are currently nine working groups focused on shot hole borers.   PSHB/KSHB updates and discussions on research, education and outreach strategies took place during group coordination meetings held, in person and via conference calls:

1. CACASA – California Agricultural Commissioners and Sealers Association (J. Deviney, Agricultural Commissioner-Santa Clara County group conference call facilitator - 3/22)
2. Emerging Tree Pests Education and Outreach Committee (A. Cornejo, US Fish & Wildlife Service, facilitator – 1/25, 2/8, 2/22, 3/8, 3/22)
3. Natural Resource / Urban Forestry Shot Hole Borer Coalition (Chaired by California Department of Fish and Wildlife – G. Sevrens, facilitator – 1/3, 2/7, 3/7)
4. Orange County Emerging Tree Pests Group
5. San Diego Association of Governments – Emerging Tree Pests Subcommittee (SANDAG)
6. Santa Barbara County Shot Hole Borer Working Group (M. Bianchi, University of California Cooperative Extension – Santa Barbara & San Luis Obispo Counties – group facilitator, 3/23)
7. University of California Emerging Tree Pests Working Group – statewide for ISHB – (S. Drill, University of California Cooperative Extension – Los Angeles & Ventura Counties – group facilitator, 3/9)
8. Ventura County Green Waste and Pest Prevention Advisory Committee
9. Ventura County Polyphagous Shot Hole Borer Working Group (S. Drill, University of California Cooperative Extension – Ventura – group facilitator)

John Boland, Southwest Wetlands Interpretive Association (SWIA) – Imperial Beach

o   Continued studying KSHB in the Tijuana River Valley riparian forest, with funding from the US Navy and US Fish & Wildlife Service

Sabrina Drill, UC Cooperative Extension – Ventura & Los Angeles Counties

o   Met with Santa Clara River Academic Coalition to discuss SHB research, monitoring, trapping efforts in the watershed – (3/1)

o   Coordinated Cooperative Extension/UC Riverside SHB coordination working group meeting in Riverside – (3/9)

o   Participated in California Agricultural Commissioners & Sealers Association (CACASA) statewide call – (3/22)

Tom Dudley, UC Santa Barbara – Marine Science Institute

o   Coordinated Santa Clara River Academic Coalition meeting for the watershed – (3/1)

Jan Gonzales, UC Cooperative Extension – San Diego

o   Participated in Coordinating Work Group Meetings/Calls:

• Natural Resources/Urban Forestry SHB Coalition (1/3, 2/7, 3/7)
• Emerging Tree Pests Education and Outreach Committee (1/25, 1/11, 3/8, 3/22)
• Statewide PSHB Group (3/22)

o   Coordinated visit to the San Diego Zoo and gave briefing on ISHB during field tour for UC ANR's Associate Vice President, Wendy Powers; Chris Greer, Vice Provost of Cooperative Extension and guests from the National eXtension program (1/24)

 

Funding, Legislation, Planning, Policy and Regulation

John Kabashima, UC Cooperative Extension – Orange County

o   Gave a team talk with the California Department of Food and Agriculture (CDFA) Director of Plant Health to the Invasive Species Council of California (ISCC) on PSHB/KSHB/FD as an example of emerging tree pests that the present system isn't addressing effectively. Ideas to address this by CDFA and the ISCC Advisory committee are incorporated in their interagency "Charting the Pest Prevention System in California" plan.  The California Assembly Speaker's office suggested we identify an Assembly Democrat who would ask the State agencies to address this issue and recommend a plan and budget.  This would be determined through either a special summit meeting or Assembly hearing. Several approachable Assemblymembers were identified to collaborate on this matter (1/5)

o   Discussed SHB funding needs with collaborators, including the Resource Conservation District of San Diego County, University of California Cooperative Extension San Luis Obispo

Surveying/Monitoring/Detection/Mapping

Dan Berry & Tim Thibault, The Huntington Gardens – Pasadena

o   Continued plant collection monitoring for 207 acres

Rosi Dagit, Resource Conservation District (RCD) of the Santa Monica Mountains – Topanga

• Conducted Santa Monica Mountains SHB trapping coordination meeting with the RCD and Santa Monica Mountains National Recreation Area staff (1/24)
• Taught a SHB trap making and monitoring workshop at Malibu Creek State Park for– (3/1
• Sandy De Simone, California Audubon – Trabuco Canyon

o   Met with Audubon Starr Ranch seasonal riparian assistants in January to devise a protocol for monitoring oaks and sycamores for pests and disease on the 4,000 acre property located in southeast Orange County 

Sabrina Drill, UC Cooperative Extension, Ventura and Los Angeles Counties

o   Met with UCCE Ventura Master Gardener Program Coordinator Leah Hanson to discuss upcoming SHB observational training and urban monitoring sites throughout the county as part of the new Tree Detective program in sycamores – 3/27/17

John Kabashima, UC Cooperative Extension - Orange County

o   Discussed SHB infestations and monitoring with City of Downey officials (1/18)

Lana Nguyen, State Parks – Orange Coast District

o   Received confirmation from the Eskalen Lab that tree specimen from Crystal Cove was negative for Fusarium dieback

Cathy Nowak, Orange County Parks – Irvine

o   UCCE completed surveys & mapping for Aliso & Wood Canyons Wilderness Park, Key Ranch, Heritage Hill, and O'Neill Regional Park to Oso Parkway

o   Monitoring continues at Irvine Regional Park

o   Twelve monitoring stations were established at Whiting Ranch Wilderness Park – Trabuco Canyon

Gail Sevrens, California Department of Fish & Wildlife, South Coast Region – San Diego

o   Hired two new Scientific Aides, Ryan Lawler and Aidan Renner. They are assembling an expanded field guide to identifying SHB in wildland settings as well as a management matrix to determine the best course of action in the event that it is found.   Theywill begin monitoring and trapping for SHB in the region

o   Worked with the SHB Survey Committee, to investigate what kind of and how frequently surveys are being done

Research Activities and Findings

Dan Berry and Tim Thibault, The Huntington – Pasadena

o   Traveled with Akif Eskalen and Richard Stouthamer to Taiwan for the purpose of PSHB bio-control and insect agents (January)

o   Finalized stress test with Colin Umeda (UC Riverside) 

John Boland, Southwest Wetlands Interpretive Association (SWIA) – Imperial Beach

o   The Tijuana River Valley is the first natural habitat to be substantially invaded by the KSHB. It first appeared in the valley in 2015 and almost immediately caused extensive damage to the riparian forests.   It is estimated a total of 355,510 willows, or 88% of the population in the valley, have already been infested. More than two billion (2 x 109) beetles were born in the valley during 2015-16. This was likely the single largest production of offspring by this beetle in the US so far.

o   KSHB has not killed all of the willow trees it infested. Many heavily damaged by the KSHB during 2015 re-sprouted in 2016. In some sites, where the willow canopy was destroyed by the KSHB, there is now an extensive short canopy of re-sprouting willow “shrubs” up to four meters tall.

o   A final report on this research will be released in April 2017

Tom Dudley, University of California Santa Barbara – Marine Institute

o   Interfaced with Institute staff and graduate researchers to monitor, trap, and research SHB in Santa Barbara and Ventura Counties

o   Attended an interagency invasive species meeting in January on the east coast, noting several talks and posters on SHB. There is a continued research effort on semiochemicals, which UCSB may be involved at the research testing level

Akif Eskalen, UC Cooperative Extension – Riverside County

o   Traveled with Richard Stouthamer (UC Riverside), Dan Berry and Terry Thibault (both from The Huntington) to Taiwan for the purpose of PSHB bio-control and insect agents (January)

Nathan Gregory, Irvine Ranch Conservancy – Irvine

o   The Irvine Ranch Conservancy surveyed lower Agua Chinon at Limestone Canyon Nature Preserve in Silverado (northern Orange County foothills) and found no signs of PSHB. However, 12 potentially infested trees were identified in Bommer Canyon Community Park, Irvine (near Turtle Ridge) with samples taken and submitted to the Eskalen Laboratory at UC Riverside. Of those 12, five were surveyed last year and found to be newly infested this year. The other seven are newly surveyed this year.

Cathy Nowak, Orange County Parks – Irvine

o   Tim Paine continued pesticide treatments at Mason Regional Park - Irvine that examine five treatments on ten trees. Focus is on compounds that have shown promise in previous trials at UC Irvine and in the laboratory

o   Akif Eskalen's final report on the pesticide trials conducted at three regional parks is forthcoming

Richard Stouthamer, UC Riverside

o   Traveled with Akif Eskalen (UCCE-Riverside), Dan Berry and Terry Thibault (both from The Huntington) to Taiwan for the purpose of PSHB bio-control and insect agents (January)

Management and Restoration

Dan Berry and Tim Thibault, The Huntington – Pasadena

o   Removed and replaced two PSHB-infested Quercus robur (English oak)

Gail Sevrens, California Department of Fish and Wildlife (CDFW), South Coast Region – San Diego

o   Inquired about trunk injection of pesticides on creek banks and in dry creek beds. CDFW pesticide unit was consulted. Learned that applications consistent with label instructions are alright to use, as long as trees are not growing in the water. Can be okay if next to water. Said ecological risk outweighs risk of insects.

o   Updating and gathering input on Southern California Shot Hole Borers/Fusarium Dieback Management Strategy for Natural and Urban Landscapes

Wood Utilization, Sanitization, and Disposal

Dan Berry and Tim Thibault, The Huntington – Pasadena

o   Continued PSHB-infested green waste grinding and material redistribution

Education and Outreach/Media Coverage

Dan Berry and Tim Thibault, The Huntington – Pasadena

o   Gave PSHB presentation to 20 physicians at the Huntington Medical Research Institute

o   Engaged with Earthwatch during an extended meeting about a citizen science initiative

Mary Bianchi, UC Cooperative Extension – Santa Barbara & San Luis Obispo Counties

o    Began education and outreach in the greater Santa Barbara area following first population of KSHB located in Montecito. Wrote and published two online articles:

1. http://www.news.ucsb.edu/2017/017516/holy-guacamole
2. https://www.edhat.com/site/tidbit.cfm?nid=179674

o   Met with Kerry Kellogg from Montecito Fire and some of their staff, along with UC statewide Fire Specialist Max Moritz (1/17) 

o   Articles will be published in the Montecito Journal, newsletters of the Montecito Association, Ennisbrook Homeowner's Association, and Westmont College

o   Gave a presentation at the Santa Barbara Fire Safe Council Meeting (2/16)

o   Outreach and tabling were conducted at the Montecito Farmer's Market and Lotusland in Montecito

California Association of Pest Control Advisers (CAPCA) – Sacramento

o   Hosted two half-day SHB educational events for agricultural and general audiences:

1. January 25 in Ventura
2. January 26 in Temecula

• Speakers included UC entomology experts Richard Stouthamer, Akif Eskalen, Frank Byrne, Tim Paine, and John Kabashima

Julie Clark De Blasio, UC Cooperative Extension – Ventura

o   Participated
in bottle-trap making workshop at Malibu Creek State Park (3/18).   Traps will be set in wildland-urban interface areas of Brentwood in the Santa Monica Mountains  

Rosi Dagit, Resource Conservation District (RCD) of the Santa Monica Mountains – Topanga

o   Coordinated a half-day SHB bottle-trap making workshop at Malibu Creek State Park (3/18). The 15 participants will support trapping efforts in the Santa Monica Mountains and San Fernando Valley

Sabrina Drill, UC Cooperative Extension – Ventura & Los Angeles Counties

o   Gave interview for California Agricultural Pest Control Advisers (CAPCA) video series on SHB (1/25)

o   Gave interview for ‘Central Coast Farm and Ranch'(2/3):

• Bug at Bay story published Spring 2017, V14N3, pp6-8

Tom Dudley, University of California Santa Barbara – Marine Science Institute

o  Coordinated the Santa Clara River (SCR) Academic Collaboration meeting held at Hansen Agricultural Research and Extension Center, Santa Paula (3/1). UCSB is establishing numerous SHB trapping sites in wildland watersheds throughout Ventura County, with a focus on areas near infestations in the SCR   

Akif Eskalen, UC Cooperative Extension – Riverside County

o   Gave ISHB presentation at two half-day educational events for agricultural and general audiences sponsored by California Agricultural Pest Control Advisors:

• January 25 in Ventura
• January 26 in Temecula
• Jan Gonzales, UC Cooperative Extension - San Diego County

o   The Southern California Green Waste-Wood Biomass Symposium was held February 9 at the Handlery Hotel in San Diego. Members of the Emerging Tree Pests Education and Outreach Committee coordinated the day-long event. It was intended to engage multiple industry and practitioner stakeholders from public and private sectors, along with researchers and policy makers. Discussions on how to best address larger regional issues related to managing residual materials of invasive pest infested and dead trees were the focus. For more information, including presentation slides see http://ucanr.edu/sites/SoCA_GWWood__Mgmt_Symposium. 108 individuals attended, with a 54% evaluation survey response rate.

• 94.8% reported their awareness about the scope, continued threat and challenges to managing surplus green waste-wood biomass increased by a moderate to great extent
• 87.9% responded they learned more about management options and strategies for green waste-wood residuals by a moderate to great extent
• 84.5% replied they are very likely to share with others what they learned at this symposium

o   Park Rangers Association of California Training and Conference

Co-presented with Gina Moran (CA State Parks) on Invasive Tree Pests including ISHB/FD, gold-spotted oak borer and South American palm weevil, February 28, 2017, La Quinta, CA.

o   Distributed ISHB and related handout materials:

• 200 SHB general audience handouts
• 50 SHB ID and Symptoms handouts
• 50 SHB Management handouts
• 25 SHB ID Field Guides
• 750 Buy It Where You Burn It firewood awareness rack cards

 

This report is a summary of known activity relating to Polyphagous and Kuroshio Shot Hole Borer/Fusarium Dieback for the stated 3-month period. If there are any additions, corrections or comments, send them to Sabrina Drill, sldrill@ucanr.edu and/or post information to the PSHB Working Group Collaborative Tools group. Report compiled by Jan Gonzales, UCCE-San Diego

PSHB Working Group Stakeholder Organizations

 

APHIS (USDA Animal and Plant Health Inspection Services)

California Agricultural Commissioners and Sealers Association (CACASA)

California Audubon, Starr Ranch

California Avocado Commission CAL FIRE (California Department of Forestry and Fire Protection) California Department of Fish and Wildlife California Department of Food and Agriculture California Firewood Taskforce California Native Plant Society California Department of Parks and Recreation California State Senate Center for Invasive Species Prevention Center for Natural Lands Management City of Pasadena City of San Diego Davey Tree Service Everest Consultants Farm Bureau-San Diego County Farm Bureau-Ventura County Los Angeles County Agriculture, Weights and Measures Los Angeles County Arboretum Los Angeles County Fire and Forestry Los Angeles County Parks National Park Service Native American Environmental Protection Coalition Nature Reserve of Orange County North East Trees NRCS (USDA Natural Resource Conservation Service) Orange County Agricultural CommissionerOrange County Fire Authority Orange County Parks Orange County Public Works Rebecca Latta Consulting ArborisResource Conservation District of San Diego Resource Conservation District of the Santa Monica Mountains River Partners San Diego County Agriculture, Weights and MeasuresSan Diego County Parks SANDAG (San Diego Association of Governments) Santa Barbara County Agriculture DepartmentSanta Barbara County Master Gardeners Santa Clara County Agricultural Commissioner/CACASA Pest Prevention Committee Southwest Wetlands Interpretive Association (SWIA) Sycuan Band of the Kumeyaay Nation The Huntington Library, Art Collections and Botanical Gardens The Nature Conservancy Tree People University of California Cooperative Extension University of California Division of Agriculture and Natural Resources (UCANR)

University of California, Irvine

University of California, Riverside

University of California, Santa Barbara

University of California, Santa Cruz

USDA Forest Service USDA Forest Service-Cleveland NF USDA Forest Service-Forest Health Protection USDA Forest Service-State and Private Forestry, Region 5

USDI Bureau of Indian Affairs

USDI Bureau of Land Management

USDI Fish and Wildlife Service

USDI National Park Service-Santa Monica Mountains National Recreation Area

Valley Crest Tree Company

Ventura County Agricultural Commissioner West Coast Arborists, Inc. Western Chapter of International Society of Aboriculture

shot hole borer galleries

shot hole borer

Trunk Injections to Control Shot Hole Borer in Avocado

Two closely related Ambrosia beetles (Euwallacea sp.) have been identified in commercial avocado groves in California.  The polyphagous shot hole borer (PSHB), detected in Los Angeles, Orange counties and recently in Ventura county, and the Kuroshio shot hole borer (KSHB), detected in San Diego and recently in Orange and Santa Barbara counties, are morphologically indistinguishable, but genetically distinct.  Already widespread in a variety of reproductive host trees common in the urban landscape (including box elder, willow, several maples, oak and sycamore species), the beetles represent a significant threat to trees in both landscape and agricultural settings.  Adult females construct galleries in the xylem system of host trees, where they cultivate symbiotic fungi (Fusarium, Paracremonium and Graphium spp.) as a food source for their developing young.  The fungi are taken up by progeny females in specialized organs within their mouthparts, and transported to other sites within the same tree, where new colonies are established, or to newly colonized hosts.  The galleries compromise the structural integrity of infested trees, which can represent a serious safety hazard in urban environments, and disrupt the flow of water and essential nutrients within the xylem.  In addition to the physical damage, the fungi extract nutrients from the xylem system, further depriving the tree of nutrients essential for healthy growth and fruit production.

An effective biological control agent is not yet available to manage the SHB in California, and so management for now must rely on the use of chemical pesticides.  The control of Ambrosia beetles and their associated fungi using

chemical pesticides is complicated because of their location inside the host trees.  The application of insecticides to the external surfaces of trees, where the beetles must first alight prior to boring, has the potential to kill beetles by contact activity, and they may also have the potential to control emerging young adults before they can re-infest the trees. 

The drawback of surface treatments is that multiple applications are often required because of the relatively short duration of efficacy.  In addition, once the beetle burrows inside the tree, surface treatments are become ineffective.  One possible solution to this problem may be the use of systemic pesticides, and scientists at UC Riverside are evaluating the use of both systemic insecticides and fungicides in a 2-pronged attack against the symbiotic system. 

Systemic pesticides are mobile within the xylem system of plants, and the fungicides could potentially target the fungi growing in the xylem and deprive the beetle larvae of a food source.  The insecticides would prevent the beetle from establishing galleries within susceptible tree hosts, and prevent the survival of beetles and their offspring already present within trees.  The big problem with systemic pesticides is getting sufficient concentrations of chemicals to the areas within the trees where the beetle and fungus occur.  Although there are exceptions, most systemic treatments are administered to the soil for uptake through the roots.  However, in mature avocado groves, the high organic matter content of the soil can prevent effective absorption by roots because the pesticide becomes bound to organic components within the soil.  Trunk injection of pesticides directly into the vascular system of trees eliminates the potential for binding of pesticides within the soil, and increases the amount of active ingredient inside the tree available to impact the beetle/fungal system.  Systemic pesticides must be formulated for trunk injection and so careful evaluation is needed to ensure optimal efficacy.  Trials are being conducted with the assistance of avocado industry and grower collaborators in areas where the SHB has been recorded.  The chemicals are injected into the trees using commercially available equipment, and the movement of the active ingredients is then monitored over time in wood core samples taken at different heights of the trees.  Two methods are being used to confirm the presence of the chemicals.  Insecticides are being quantified using ELISAs that are specific for the active ingredients under investigation.  Wood cores taken from trees treated with fungicides are placed in direct proximity to the fungal pathogens growing on agar plates to determine if growth of the fungus is inhibited.

The investigations are still at an early stage, but the researchers are optimistic that they will develop effective control strategies for the SHB that growers can incorporate into their overall pest management programs.  Laboratory based bioassays have been used to identify several pesticides that are toxic to the beetle and fungi.  The objective of the field trials is to determine whether these chemicals can be utilized as trunk injection agents for the protection of avocado trees. Anyone interested in finding out more about the SHB should go to the web site maintained by Dr. Akif Eskalen at:

 http://eskalenlab.ucr.edu/avocado.html

 

wood coring

How to Attract an Ambrosia Beetle that Attacks Avocado and Sycamore

There's a lot of work being done in Florida on a pest/disease complex like we have here with Shot Hole Borer and Fusarium fungus – Fusarium Dieback. This hits avocados and a lot of other native trees like sycamore, willow and coast live oak.  Some of the success in Florida may be applicable and we are working with their researchers there to adapt some of the techniques here.

Redbay ambrosia beetle, Xyleborus glabratus, is a wood-boring pest that has now invaded nine states in the southeastern United States. The beetle's dominant fungal symbiont (Raffaelea lauricola) is phytopathogenic, inducing laurel wilt in trees within the family Lauraceae. Members of the genus Persea are particularly susceptible to the lethal disease, including native redbay (P. borbonia) and swampbay (P. palustris), as well as commercial avocado. Cubeb oil lures are the current standard for detection of X. glabratus, but recently eucalyptol and a 50% α-copaene oil have been identified as additional attractants. This study used a combination of choice bioassays, field cage release-and-recapture assays, and a 12-week field trial to compare efficacy of eucalyptol and copaene lures relative to commercial cubeb lures. In addition, gas chromatography (analyzer for volatiles) was used to quantify emissions from lures field-aged for 12 wk. In field cage assays, copaene lures recaptured a higher percentage of released beetles than cubeb lures. In the field test, cubeb lures captured fewer beetles than copaene lures, and lowest captures were obtained with eucalyptol lures. Both copaene and cubeb lures were effective in attracting X. glabratus for 12 weeks, but field life of eucalyptol lures was only 4 weeks, consistent with the quantification of lure emissions. Results suggest that the 50% α-copaene lure provides the best pest detection currently available for X. glabratus.

So why is this important? For one, it will serve as a tool for more effectively monitoring the presents of the beetle.  But more importantly, it might be used as a lure to attract them away from trees.  Fool them into going somewhere else, like to die.

shot hole borer

Read more