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Polyphagous Shot Hole Borer in the Arroyo
Sco6 David Cher Arroyo Seco Founda<on
May 2015
Polyphagous Shot Hole Borer • PSHB or Euwallacea sp. • Invasive beetle, probably
from Vietnam originally • Observed on over 110
plant species in California; 31 reproduc<ve host species and coun<ng.
• First observed in Los Angeles in 2003; not linked to tree injury un<l 2012.
Photo credit: Eskalen Lab, UC Riverside
Polyphagous Shot Hole Borer Polyphagous = poly (many) + phagous (feeding and a specific food)
Photo credit: Arroyo Seco Founda<on
Hole 0.85 mm
Female PSHB 1.8–2.5 mm long
Poten<al Ecological Impacts on Southern California
• Loss of trees • Loss of wildlife habitat • Increased risk of fire • Hazard for recrea<onal users • Adverse impact on food system
The Pest/Disease Complex
• Female PSHB bores galleries in tree. • Introduces two species of fungi, which it feeds on: Fusarium euwallaceae and Graphium sp.
• Fungi interrupt the tree’s vascular system, causing Fusarium dieback (FD).
• PSHB reproduces (3–4 genera<ons annually), offspring usually the re-‐infest same tree, and the cycle repeats un<l the tree dies.
Arroyo Seco Trees at Risk • Bigleaf maple (Acer macrophyllum) • Box elder (Acer negrundo) • White alder (Alnus rhombifolia) • California sycamore (Platanus racemosa) • Fremont co6onwood (Populus fremon<i) • Coast live oak (Quercus agrifolia) • Engelmann oak (Quercus engelmannii) !! • Valley oak (Quercus lobata) • Red willow (Salix laevigata)
Some Non-‐Na<ve Trees at Risk
• Japanese maple (Acer palmatum) • Persimmon (Diospyros sp.) • Olive (Olea europaea) • Blue palo verde (Parkinsonia florida) • Avocado (Persea americana) • Cork oak (Quercus suber) • Weeping willow (Salix babylonica)
Signs of Infesta<on
• Round entry/exit hole about the size of a ballpoint pen head
• White ring around hole with discolora<on/swea<ng.
• Details vary by tree species. • If in doubt, bark may be scraped away to reveal necrosis around hole. Sterilize tools with bleach or alcohol solu<on aherward to prevent spreading FD.
Photo credit: Arroyo Seco Founda<on Photo credit: ucanr.edu/blogs/Safelandscapes
Sycamore Oak
Photo credit: Arroyo Seco Founda<on
Arroyo Seco Tree Inventory
• Collabora<on between Pasadena Department of Public Works and Arroyo Seco Founda<on.
• Volunteers are collec<ng data from the Arroyo Seco and adjacent parks in Pasadena.
• Data is logged and mapped using Esri’s Collector for ArcGIS mobile applica<on.
• Long-‐term vision: data can be used to develop a response strategy, a restora<on plan, and to seek funding.
What Can We Do?
• On a large scale, we s<ll do not know. • Keep an eye out and report infesta<ons. • If you are removing an infested tree: – Mulch wood to pieces smaller than ½ inch. – Solarize mulched wood on site. – Sterilize tools with bleach or alcohol solu<on to prevent spreading FD.
Don’t Move Infested Wood
We need your help!
For volunteer informa<on, contact:
Sco6 David Cher
[email protected] (323) 405-‐7326
arroyoseco.org/pshb
Informa<on about trees in Pasadena
Darya Barar City of Pasadena, Forestry Opera<ons
[email protected] (626) 744-‐3846
More informa<on and to report infesta<ons:
Dr. Akif Eskalen [email protected]
(951) 827-‐3499 eskalenlab.ucr.edu