Invasive Shot Hole Borers (ISHB) (Part III)

Invasive Shot Hole Borers (ISHB) (Part III)

Where do we monitor for SHB?

When looking for a host tree, the shot hole borers prefer live, healthy trees, unlike most ambrosia beetles that prefer stressed or dying trees. And they also prefer well-irrigated trees, which includes riparian trees. The polyphagous shot hole borer has been detected in 342 tree and woody plant species in CA, including agricultural, riparian and urban trees. Currently, there are 64 confirmed species of trees in which the beetles can successfully grow their fungus and complete their life cycle. 

Susceptible trees include many of the species commonly used for landscaping; like 

• sycamores
• oaks
• cottonwoods
• box elder
• willows  
• maples
• castor bean (preferred host, not a tree)
• many others 

Shot hole borers can also infect Avocado, but growers can manage infestations by using best management practices.To find the full list of ISHB reproductive hosts (including the canker-associated hosts) please visit pshb.org.

White powdery exudate (sugar volcanoes) are a common symptom of ISHB infestation in avocado trees. (Credit: Monica Dimson, UCCE Orange Co.)

Trunk of a heavily infested California sycamore (Platanus racemosa). Note the staining around each ISHB entry hole. (Credit: Beatriz Nobua-Behrmann)

Lindgren Traps or Bottle Traps with a Quercivorol lure are used to monitor and trap shot hole borers. Lures can be purchased from UCSB. 

Standard shot hole borer Lindgren trap.