![Male (left) and female walnut twig beetles. [L. Strand]](https://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/34720small.jpg)
Today's post for National Invasive Species Week highlights two ambrosia beetles that are detrimental to certain trees. Ambrosia beetles are highly specialized beetles that excavate tunnels in usually weakened or dead trees and cultivate fungal gardens, which they feed upon. Below are two such invasive beetle-fungal complexes that are currently impacting trees and forests in California.
Walnut twig beetle and thousand cankers disease. Walnut twig beetle, Pityophthorus juglandis, is a tiny bark beetle that attacks only walnut trees. The beetle has been in California for many decades but recently became associated with a new fungus, Geosmithia morbida. The fungus kills the phloem and cambium of...
![Bark staining on coast live oak caused by larvae of the goldspotted oak borer. [Photo by Tom Coleman, USDA Forest Service]](https://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/34690small.jpg)
Goldspotted oak borer. First identified in eastern San Diego County in 2004, the goldspotted oak borer, Agrilus auroguttatus, has killed over 25,000 California native red oaks since its arrival and has now been detected in Riverside County. Larvae feed deep within the phloem, and adults are rarely seen. Infestations are recognized by the presence of D-shaped exit holes on trees, often accompanied by bark staining and crown decline. There are currently no good ways to manage the pest in moderate to severely infested trees. Contact your agricultural commissioner if you find infestations outside the known infested area.
For more information on this pest, infestation zones, and ways you can help limit the...
![Citrus fruit. [J.K. Clark]](https://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/34471small.jpg)
News release from the California Department of Food and Agriculture (CDFA)
February 3, 2016 - Two additional trees in San Gabriel have tested positive for Huanglongbing. The two trees, an orange and a kumquat, are on separate properties but are both within the core area in San Gabriel where 10 diseased trees were confirmed last summer. Given the close proximity, there will not be a quarantine expansion.
One of the HLB-positive trees has already been removed and California Department of Food and Agriculture officials are in the process of contacting the other homeowner to schedule tree removal. Agriculture officials are working quickly in the area.
![Asian citrus psyllid and nymphs. [Photo by M.E Rogers]](https://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/34313small.jpg)
News release from the California Department of Food and Agriculture (CDFA)
January 28, 2016 – A new portion of Stanislaus County has been placed under quarantine for the Asian citrus psyllid (ACP) following the detection of one ACP within the City of Oakdale. The quarantine zone measures 133 square miles, bordered on the north by E Sonora Road; on the south by Milnes Road; on the west by Stanislaus County Boundary; and on the east by Oakdale Irrigation District South Main Canal. Maps for the new quarantine area in Oakdale and the existing quarantine area in Turlock in are available
![Asian citrus psyllid and nymphs. [Photo by M.E Rogers]](https://ucanr.edu/blogs/UCIPMurbanpests/blogfiles/34236small.jpg)
News release from California Department of Food and Agriculture
SACRAMENTO – January 25, 2016 – A new portion of Fresno County has been placed under quarantine for the Asian citrus psyllid (ACP) following the detection of one ACP within the City of Fresno. The quarantine zone measures 97 square miles, bordered on the north by W Alluvial Avenue; on the south by W North Avenue; on the west by N Chateau Avenue; and on the east by S Chestnut Avenue. The quarantine map for Fresno is available online at: www.cdfa.ca.gov/go/acp-maps. Please...
