The polyphagous shot hole borer (SHB), Euwallacea sp., and Fusarium dieback, Fusarium euwallaceae, are a new insect: disease complex causing injury and mortality to numerous native and ornamental hardwood trees and shrubs in southern California. The ambrosia beetle has a wide host range and can complete development in >20 species, including avocado, Persea americana, bigleaf maple, Acer macrophyllum, California box elder, Acer negundo var. californicum, California sycamore, Platanus racemosa, coast live oak, Quercus agrifolia, castorbean, Ricinus communis, red willow, Salix laevigata, and white alder, Alnus rhombifolia.
U.S. Forest Service Region 5 Forest Health Protection recently created a document illustrating the injury symptoms created by the SHB. Click here to download the document.
Additional information about this pest complex can be found here.