“The only biodiversity we’re going to have left is Coke versus Pepsi. We’re landscaping the whole world one stupid mistake at a time” – Chuck Palahniuk

I have two favorite California native trees and they are both endangered. The Coastal Live Oak (Quercus agrifolia) and the California Sycamore (Platanus racemosa) are both under threat of being killed off by a new pest called Polyphagous Shot Hole Borer.

Unfortunately, this beetle is not only targeting my favorite natives, but are also found infesting many other common Southern California trees (110 by current estimates), including Avocados, London Plane Tree (a relative of the Sycamore), Palo verde, and Liquidambar, to name a few. There seems to be very little we can do except identify, contain, and very carefully destroy infested trees. I included a link to a PDF sheet that talks about current research and problem that the beetle is causing. Basically, the Shot Hole Borer carries two unfriendly fungi that causes a disease called Fusarium Dieback which chokes off the movement of water and nutrients in the tree.

Click here for a guide to symptoms in various tree species.

Click here for a guide to symptoms in various tree species.

Although there are plenty of PhD’s at UC Riverside and the Los Angeles County Department of Agriculture working on the problem, there are no solutions. I have direct experience with this devastating disease which is killing off dozens of mature California Sycamore trees at our new park in Burbank. We conceptualized the park three years ago using the existing Sycamore trees as the primary shade tree. However, today as we begin to construct the park these mature trees are gone because of the borer beetle infestation.

Just as the Eucalyptus Longhorn Borer wiped out the Eucalyptus trees during the 1980’s, this new pest is an another potential beetle that is quietly devastating to our natural and ornamental landscapes. Unfortunately, the researchers are telling us designers to stop using the 110 different species that have been identified to be susceptible to the beetle. The questions remain: which trees will be left for us to include in our designs? And more fundamentally, what are we to do as designers and stewards of our landscapes?

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