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July 2020                 July 16, 2020  Vol. 7, Issue 1
Save the Date!   

July 29: California Oak Mortality Task Force (COMTF),   Virtual Executive Committee Meeting Registration

August 8 - 12: 2020 American Phytopathological Society Annual Meeting, Virtual Annual Meeting
September 9: University of California Ag Expert Talks, What's in your Orchard: Protecting California from Invasive Species  

November 15-18: Entomological Society of America, Virtual Annual Meeting

November 18-19: California Forest Pest Council, Virtual Annual Meeting  
A New Ambrosia Beetle: The Mediterranean Oak Borer
     The Mediterranean oak borer (MOB; Xyleborus monographus Fabricius), an ambrosia beetle native to the Mediterranean regions of Europe, the Middle East, and North Africa, was detected in declining oak ( Quercus spp.) trees for the first time in North America in Napa County, California in 2019 (Fig. 1). Subsequently in early 2020, it was confirmed in the neighboring counties of Lake and Sonoma. Within its native range, MOB is a pest primarily of oaks, and one of its symbiotic ambrosia fungi, Raffaelea montetyi, has been shown to cause wilt disease in cork oaks in Portugal. In the California infestation, MOB was detected in valley oak ( Q. lobata) and blue oak ( Q. douglasii), and R. montetyi was recovered from both species.
Figure 1: Xyleborus monographus 
adult & medium tip pencil. Photo by Curtis Ewing, CALFIRE.

MOB appears to initially attack the crown of host trees, where it can kill branches, with persistent infestations spreading to the main stem and eventually killing t he entire tree (Fig. 2). The extensive network of MOB galleries can weaken trees, making 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 infestations, so it is unclear if the insect and its ambrosia fungi can kill healthy North American oak species.

Figure 2: Valley Oak killed by X. monographus. Photo by Curtis Ewing, CALFIRE
Signs of MOB infested trees are thin canopies, bo ring dus t in cracks of the bark, and occasionally sap flux; however, these sy mptoms could be caused by other diseases and boring insects. The best wa y to confirm MOB is from the architecture of its galleries, which are trellis-like, intersecting, and fan out in a single plane. This gallery pattern distinguishes it from native  Monarthrum spp.  ambrosia beetles, which have galleries that branch from a single point and do not intersect neighboring galleries (Fig. 3). These native beetles only attack trees that are already dead, dying, or diseased.

Research is currently underway to determine the best methods of control. However, it is always best to not move wood that is  suspected to be infested. Like other ambrosia beetles, chipping infested material to sizes <3" or solarizing cut wood may help to mitigate spread of MOB.

Figure 3: Gallery pattern of X. monographus. Photo by Curtis Ewing, CALFIRE.

For more information please visit

2020 California Forest Pest Council Annual Meeting
After careful consultation with the CFPC executive committee regarding the health and safety of everyone in our industry and profession and communities, we have made the difficult decision to move the CPFC annual meeting from an in-person meeting to an interactive online webinar meeting. The meeting is still scheduled to take place on November 18th & 19th.

Due to the increased and overwhelming concerns about the COVID-19 virus, we felt this was the right decision during such an uncertain and unprecedented global situation. We are very disappointed that we are not to be holding this meeting in person; however, for the safety of everyone we feel this is the best alternative.

We will still be applying for continuing education hours for the online meeting to meet hours needed by the attendees. Updates will be shared on the CFPC website, .

We thank everyone for their understanding to this change in format and know that we look forward to hopefully having the CFPC annual meeting in person next year for the council's 70th anniversary.

Warmest regards and to staying healthy,
Bob Rynearson
Chairman, California Forest Pest Council
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When buying firewood for camping or home heating this fall, remember to buy wood sourced local to where you will be using it, helping to minimize the spread of pests and diseases - Buy It Where You Burn It.  For a list of local firewood dealers, go to

The California Forest Pest Council
California Forest Pest Council | (805) 550-8583 | |

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