The polyphagous shot hole borer is a beetle the size of a sesame seed, yet it has already destroyed great swathes of forest and parkland in Perth. Many think it’s only a matter of time before it targets Sydney’s beloved trees. What can be done? Plant pathologist Prof. Brett Summerell is Sydney Botanic Gardens’ Chief Scientist. Tonight he joins Elizabeth Farrelly on The Sydneyist to talk about this threat, and the role of Botanic Gardens more generally.