Posts Tagged: Forest Trees and Products
New Invasive Insect: Mediterranean Oak Borer
The Mediterranean oak borer (Xyleborus monographus), or MOB, is an invasive ambrosia beetle that was first collected from declining oak trees (Quercus spp.) near Calistoga (Napa County) in 2019 (Fig 1). Subsequently in early 2020, the beetle was detected in the neighboring counties of Lake and Sonoma, and more recently a separate infestation was discovered in suburbs near Sacramento. MOB is native to the Mediterranean regions of Europe, the Middle East, and North Africa and was likely introduced to North America in infested wood material. Within its native range MOB is a pest primarily of dead and dying oaks. In California, MOB has been detected in valley oak (Q. lobata) and blue oak (Q. douglasii). Given the cryptic nature of the insect, the extent of the infestations, and presence of dead trees with evidence of the beetle, the insect has likely been in California for more than five years.
Ambrosia beetles are interesting insects because they carry symbiotic ambrosia fungi which they cultivate along their galleries (boring tunnels) for food. Most ambrosia fungi are weak pathogens (typically only colonizing the tissue near the galleries), but a fungus associated with MOB, Raffaelea montetyi, appears to cause wilt disease in cork oaks in Portugal. This fungus and several others associated with MOB, have been recovered from infested trees in California and research is underway to determine if these ambrosia fungi could cause similar diseases in North American oak species.
MOB appears to initially attack the canopy of host trees where it kills branches, with persistent infestations spreading to the main stem and eventually killing the tree (Fig. 2). The extensive network of MOB galleries can weaken trees and make them more susceptible to failure. Thus far, trees in California with MOB infestations appear to have been stressed by other biotic and abiotic factors prior to MOB colonization, so it is unclear if the insect and its ambrosia fungi can infest and kill healthy trees.
Signs of MOB infested trees are declining canopies, tiny exit holes and boring dust in cracks of the bark, and occasionally sap flux; however, these symptoms could be caused by other boring insects or diseases. The best way to detect MOB infested trees is to observe the pattern of canopy decline. MOB begins by colonizing a large branch in the upper canopy, so newly infested trees will often have one declining branch while the rest of the canopy appears healthy. As the infestation progresses, the entire canopy begins to decline and in some instances, heavily infested branches can produce extensive epicormic sprouting with leaves diminished in size and densely clustered (sometimes referred to as “popcorn foliage”). The most reliable way to confirm MOB is from the architecture of its galleries, which are trellis-like, intersecting, and fan out in a single plane (Fig. 3A). These gallery patterns distinguish it from native Monarthrum spp. of ambrosia beetles, which have galleries branching from a single point and do not intersect neighboring galleries (Fig. 3B). These native beetles will only attack trees that are already dead, dying, or diseased.
Research is currently underway to determine the extent of the two infestations and to find effective management strategies to control MOB. From other similar invasive insects, such as the shot hole borer in southern California, options like chipping (≤1” size), solarization, burning, or burying infested material will likely be crucial in mitigating spread. However, since infestations can be cryptic for several years, there is significant potential for the beetle's range to expand as they can be moved in infested wood and are capable fliers. The best method of control is preventing the movement of the insect and its host material from known infested areas. For more information, please visit: ucanr.edu/sites/mobpc.
If you have a tree that you believe to be infested, please contact the California Department of Food and Agriculture:
- Pest Hotline: 1-800-491-1899
- Report a Pest: cdfa.ca.gov/plant/reportapest/
Michael I. Jones, PhD, UC Cooperative Extension Forest Advisor, Mendocino, Lake, & Sonoma County, mjones@ucanr.edu, (707) 463-4495
New Invasive Insect: Mediterranean Oak Borer
The Mediterranean oak borer (Xyleborus monographus), or MOB, is an invasive ambrosia beetle that...
Fig1 MOB female closeup
Biochar for and from the forest conference
Western Forestry and Conservation Association is sponsoring a one-day training conference on...
Earth Economics Rim Fire Report Published
Earth Economics has recently released a report assessing the economic impact of the 2013 Rim Fire. The San Francisco Public Utilities Commission commissioned this report which addresses fire impact on a range of ecosystem service values.
As of September 17, 2013, the Rim Fire covered over 256,000 acres of land and direct firefighting costs were estimated at over $127 million. This report was compiled using satellite data from September 17, 2013, before the fire was fully contained, and represents a conservative underestimation of lost ecosystem benefit and direct costs.
The study categorized the overall burn area into eight distinct vegetation types and valued them based on 10 of 18 identified environmental benefits.
Vegetation Type |
Environmental Benefits |
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Overall first year benefit losses are estimated at between $100 million to $736 million. The report also identified pre-fire values of environmental benefits ($210 million to $1.5 billion) and available carbon storage ($101 million to $782 million). These values represent estimated total value of these resources and while these benefits have not been wholly lost following the fire, it will take decades if not longer for them to fully recover.
The report also identifies additional benefit losses from fire stress mortality, long term human health costs, and ecosystem services damage from snow pack, soil structure, and water filtration degradation among others. These are important issues that were not specifically considered due to a lack of primary local data at time of assessment but represent additional strain on the economics of ecosystem management.
With large scale high severity wildfire becoming more common throughout California, the cost of suppression is rapidly becoming a major issue in lands management.
This report presents a detailed look into the various costs incurred by a large scale wildfire event many of which can be avoided or offset by alternative management strategies. It remains to be seen how these lost services and values will affect the overall cost of the Rim Fire moving into the future, but this report shows the immediate first year's loss already representing a significant portion of the overall available environmental utility.
For the full report, click the link below:
Open Application Period for Wood Energy Development Assistance
The Watershed Research and Training Center (WRTC), as administrator of the California Statewide Wood Energy Team (SWET), is now accepting applications for assistance for development of wood energy projects. SWET is a partnership formed with the ad hoc California Forest Biomass Working Group and funded through a Cooperative Agreement with the USDA Forest Service to provide early stage wood energy assistance to communities across the state of California.
If your organization, group, or community is interested in early-stage assistance with a current or future wood energy project, please visit www.cawoodenergy.org to learn more. The SWET will consider a variety of assistance including access to our network of information about site assessment, pre-feasibility and feasibility assessment, financing, and workshop and outreach assistance. There is also potential for limited reimbursement of cost of consultants. Assistance with other barriers to development will be considered on a case-by-case basis.
The SWET’s implementation members are experienced professionals representing a variety of fields including government, academia, non-governmental organizations and the private sector. SWET organizational partners include:
USDA Forest Service | University of California |
Watershed Research and Training Center | TSS Consultants |
Sierra Nevada Conservancy | The California Energy Commission |
CAL FIRE | Sierra Institute for Environment and Community |
To get started, the first step is to contact the team. Call or email Angie Lottes at 314-610-2237 or angie@thewatershedcenter.com. You will be asked to fill out a brief application (available at www.CAWoodEnergy.org). Applications will be accepted on a rolling basis and considered monthly. It should not take longer than two months for requests for assistance to be processed. Basic questions, information and networking requests will be considered immediately. Funds for assistance will be available until expended.
Download official announcement here
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